U.S. patent application number 12/046530 was filed with the patent office on 2008-09-18 for golf club head and golf club.
This patent application is currently assigned to Bridgestone Sports Co., Ltd. Invention is credited to Wataru Ban, Hideo Matsunaga, Koki Motoyoshi.
Application Number | 20080227565 12/046530 |
Document ID | / |
Family ID | 39763271 |
Filed Date | 2008-09-18 |
United States Patent
Application |
20080227565 |
Kind Code |
A1 |
Ban; Wataru ; et
al. |
September 18, 2008 |
Golf Club Head and Golf Club
Abstract
This invention provides a wood golf club head having a loft
angle of not more than 15.degree.. In this golf club head, a
progression length FP from a leading edge of a face to an axis line
of a shaft axis and a horizontal length VZG from the leading edge
of the face to a center of gravity of the head in a depth direction
satisfy the following expression; -2<VZG-2.times.FP<2.
Inventors: |
Ban; Wataru; (Chichibu-shi,
JP) ; Matsunaga; Hideo; (Chichibu-shi, JP) ;
Motoyoshi; Koki; (Tokyo, JP) |
Correspondence
Address: |
PAUL, HASTINGS, JANOFSKY & WALKER LLP
875 15th Street, NW
Washington
DC
20005
US
|
Assignee: |
Bridgestone Sports Co., Ltd
Tokyo
JP
|
Family ID: |
39763271 |
Appl. No.: |
12/046530 |
Filed: |
March 12, 2008 |
Current U.S.
Class: |
473/343 |
Current CPC
Class: |
A63B 53/042 20200801;
A63B 53/0466 20130101; A63B 53/0416 20200801; A63B 53/0408
20200801 |
Class at
Publication: |
473/343 |
International
Class: |
A63B 53/04 20060101
A63B053/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 14, 2007 |
JP |
2007-064896 |
Claims
1. A wood golf club head having a loft angle of not more than
15.degree., wherein a progression length FP from a leading edge of
a face to an axis line of a shaft axis and a horizontal length VZG
from the leading edge of the face to a center of gravity of the
head in a depth direction satisfy the following expression:
-2<VZG-2.times.FP<2.
2. The head according to claim 1, wherein the FP satisfies 12
mm<FP<20 mm.
3. The head according to claim 2, wherein the FP satisfies 12
mm<FP<17 mm.
4. A golf club comprising a wood golf club head according to claim
1.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a wood golf club head and a
golf club and, more particularly, to a wood golf club head having a
loft angle of not more than 15.degree. and a golf club.
[0003] 2. Description of the Related Art
[0004] In a golf club, the shape of the head greatly influences
playability, directionality of a hit ball, and the like. There have
been provided and proposed heads with a variety of designs in order
to improve ball catchability, playability, directionality of a hit
ball, and the like by adjusting a face progression (FP)
representing the length from the axis line of the shaft to the
leading edge of the face, the center of gravity position, a gravity
depth (VZG) representing the length from the leading edge of the
face to the center of gravity in the depth direction, a gravity
depth (ZG) representing the length from the face to the center of
gravity, a loft angle, a gravity length (GL) representing the
length from the axis line of the shaft to the center of gravity,
the height of the sweet spot, and the like.
[0005] In general, as a factor of ball catchability, a small face
progression (FP) is considered to provide high ball catchability
and a large FP is considered to provide low ball catchability. In
this specification, high ball catchability means that the head
rotation is encouraged through impact so that it is easy to hook
(difficult to slice) a ball, and low ball catchability means that
the head rotation is not encouraged through impact so that it is
easy to slice (difficult to hook) a ball. The center of gravity
depth (VZG) represents a relative center of gravity depth in the
head. Generally, a larger center of gravity depth tends to provide
better ball catchability.
[0006] When ball catchability is excessively high or low, the
playability becomes poor and the directionality of the hit ball
becomes unstable. These phenomena are considered to occur because
the behavior of the golf club head during a swing has a lack of
stability and a stable head rotation cannot be controlled. A factor
for controlling stable head rotation is assumed to be determined
from the relationship between the hitting point, center of gravity
position, and shaft axis, but no distinct relationship has been
found.
[0007] As a golf club head that is focused on the FP value, one
with an FP value falling within a range of 7 mm to 20 mm (both
inclusive) has been proposed (for example, see Japanese Patent
Laid-Open No. 11-178958). Another golf club head that is focused on
the center of gravity depth (ZG) has also been proposed (for
example, Japanese Patent Laid-Open No. 2002-210045).
[0008] With a design in which only the value of one factor such as
the FP value or ZG value is defined, the behavior of the golf club
head during a swing cannot be stabilized. Therefore, stable head
rotation and ball catchability cannot be controlled, resulting in
poor playability. Accordingly, a player cannot selectively hook or
slice a ball. In addition, the directionality of the hit ball is
unstable.
SUMMARY OF THE INVENTION
[0009] It is an object of the present invention to provide a wood
golf club head and a golf club in which the behavior of the golf
club head during a swing is stable, stable head rotation can be
controlled, and playability and directionality of a hit ball are
excellent.
[0010] According to an aspect of the present invention, there is
provided a wood golf club head having a loft angle of not more than
15.degree., wherein a progression length FP from a leading edge of
a face to an axis line of a shaft axis and a horizontal length VZG
from the leading edge of the face to a center of gravity of the
head in a depth direction satisfy the following expression;
-2<VZG-2.times.FP<2. A golf club comprising such a wood golf
club head is also provided.
[0011] The FP preferably satisfies 12 mm<FP<20 mm, and more
preferably 12 mm<FP<17 mm.
[0012] Further features of the present invention will become
apparent from the following description of exemplary embodiments
(with reference to the attached drawing).
BRIEF DESCRIPTION OF THE DRAWING
[0013] FIGURE is a side view of a golf club head 1 according to an
embodiment of the present invention.
DESCRIPTION OF THE EMBODIMENTS
[0014] Preferred embodiments of the present invention will now be
described in detail in accordance with the accompanying
drawing.
[0015] FIGURE is a side view of a wood golf club head 1 including a
hollow portion 10. A head main body 2 is provided with a hosel 3
and a face plate 5 is fixed to the head main body 2. A shaft (not
shown) is mounted to the hosel 3, thereby forming a golf club. The
loft angle of the golf club head 1 is formed to be 15.degree. or
less.
[0016] The progression length from a leading edge 41 of a face 4 to
an axis line S of the shaft is defined as FP, that is, the face
progression. The horizontal length from the leading edge 41 of the
face 4 to a center of gravity G in the depth direction is defined
as VZG, that is, the center of gravity depth.
[0017] The golf club head 1 is formed to satisfy
-2<VZG-2.times.FP<2. The FP value preferably satisfies 12
mm<FP<20 mm, and more preferably 12 mm<FP<17 mm. When
the FP value is 12 mm or less, a player feels a sense of discomfort
for a head shape, and ball catchability becomes excessively high,
resulting in the ball flying to the left. When the FP value is 20
mm or more, even though the behavior stability of the golf club
head during a swing improves, ball catchability decreases.
[0018] The VZG value is set to satisfy -2<VZG-2.times.FP<2
described above in accordance with the FP value. The VZG value is
preferably greater or equal to 24 mm and more preferably greater or
equal to 25 mm. The VZG value is preferably 42 mm or less, more
preferably 40 mm or less and still more preferably 38 mm or
less.
[0019] The material and volume of the golf club head 1 are not
particularly limited as far as they fall within the range of an
ordinal wood head. For example, a material such as a titanium
alloy, stainless steel, or the like can be employed, and the volume
can be about 350 cc to 500 cc.
[0020] Note that when the volume is 400 cc or more, the center of
gravity length representing the length the perpendicular from the
axis line S to the center of gravity G is preferably 50 mm or less,
more preferably 40 mm or less. When the volume is 400 cc or more,
the center of gravity length generally becomes long, resulting in
poor playability. The playability can be improved by decreasing the
center of gravity length. The center of gravity length is
preferably greater or equal to 25 mm.
[0021] When the volume of the golf club head 1 is large and is
about 400 cc or more, it increases a hitting sound and worsens
feeling of playability and hitting feel. For this reason, it is
preferable to mount a member made of a material having a relatively
low specific gravity as a metal and a vibration damping effect,
such as magnesium or a magnesium alloy, to the back face on the toe
and heel sides so as to reduce the hitting sound and improve the
feeling of playability. This alloy member is shaped into a screw 7
which can be screwed toward the hollow portion 10 from a recessed
portion 8 provided in the back face.
[0022] A large-size head having a large volume readily provides low
ball catchability. Accordingly, the wall thickness of the crown
portion from the face 4 side to the back face side is preferably
increased as compared to other head portions. For example, it is
possible to form a wall thickness L of the hosel 3 on the back face
side to be 0.6 mm; a wall thickness M on the further back face
side, 0.7 mm; and a wall thickness N on the still further back face
side, 1.0 mm. With this arrangement, the ball catchability can
improve.
EXAMPLE
[0023] Samples of Examples 1 to 3 and Comparative Examples 1 to 9
were fabricated as the golf club heads 1 each having the head main
body 2 made of a titanium alloy and the face plate 5 made of
titanium. All the golf club heads of Examples 1 to 3 and
Comparative Examples 1 to 9 had a volume of 410 cc but different FP
values (mm) and VZG values (mm). A golfer actually hit a ball using
each golf club head of Examples 1 to 3 and Comparative Examples 1
to 9 and checked the feeling of ball catchability, that of the
behavior stability during a swing, the side spin, the launch
direction, and the trajectory. Table 1 shows the results. Note that
in Table 1, the units of FP and VZG -2.times.FP are in mm. A plus
sign (+) of a value of the side spin represents a slice spin and a
minus sign (-) represents a hook spin. When viewed from above with
respect to the target line, the clockwise spin is represented by
+and the counterclockwise spin is represented by -. The unit of the
side spin is rpm. Trajectory indicates a shift amount in the left
and right with respect to the target direction. A plus value
indicates a case in which the trajectory shifted to the right with
respect to the target direction, and a minus value indicates a case
in which the trajectory shifted to the left. The unit of the
trajectory is in m.
TABLE-US-00001 TABLE 1 Behavior Stabillity VZG Catchabl- During
Launch -2 .times. ility Swing Side Direc- Trajec- FP FP (Feeling)
(Feeling) Spin tion tory Compar- 13 -4 Good Large 200 Right 10
ative flight Example curveture 1 Example 13 0 Good
.largecircle.Stable -200 Center -5 1 Compar- 13 4 Good Unstable
-600 Left -15 ative Example 2 Compar- 16 -4 Excellent Large 400
Right 15 ative flight Example curveture 3 Example 16 0 Excellent
.largecircle.Stable 0 Center 0 2 Compar- 16 4 Excellent Unstable
-400 Left -15 ative Example 4 Compar- 18 -4 Poor Large 600 Right 20
ative flight Example curveture 5 Example 18 0 Poor
.largecircle.Stable 200 Center 5 3 Compar- 18 4 Poor Unstable -200
Left -10 ative Example 6 Compar- 21 -4 Worst Large 800 Right 25
ative flight Example curveture 7 Compar- 21 0 Worst
.largecircle.Stable 400 Center 15 ative Example 8 Compar- 21 4
Worst Unstable 0 Left 5 ative Example 9
[0024] As shown in the results in Table 1, in Examples 1 to 3, the
golf club head during a swing has a stable behavior, excellent
playability, and excellent directionality of the hit ball.
[0025] While the present invention has been described with
reference to exemplary embodiments, it is to be understood that the
invention is not limited to the disclosed exemplary embodiments.
The scope of the following claims is to be accorded the broadest
interpretation so as to encompass all such modifications and
equivalent structures and functions.
[0026] This application claims the benefit of Japanese Patent
Application No. 2007-64896, filed Mar. 14, 2007, which is hereby
incorporated by reference herein in its entirety.
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