U.S. patent application number 09/998178 was filed with the patent office on 2002-06-06 for face structure of hollow-body metal golf club head.
Invention is credited to Yoneyama, Minoru.
Application Number | 20020068646 09/998178 |
Document ID | / |
Family ID | 18838693 |
Filed Date | 2002-06-06 |
United States Patent
Application |
20020068646 |
Kind Code |
A1 |
Yoneyama, Minoru |
June 6, 2002 |
Face structure of hollow-body metal golf club head
Abstract
The present invention relates to a face structure of a
hollow-body, metal golf club head, comprising a face of laterally
elongated shape, a crown and a sole plate fixed thereto, and
particularly to a face structure having thin-walled areas for
extended, stable carry and horizontally stabled trajectory. The
face 11 has a thick-walled area 15a of uniform thickness formed at
the backside thereof, which extends from the heel side to the toe
side thereof over the hitting area 16a, and with thin-walled areas
15b, 15c of uniform thickness formed above and below the
thick-walled area 15a. An elongated portion 17 for fixing the crown
and the sole plate is formed projecting backward on the backside
periphery of the face 15.
Inventors: |
Yoneyama, Minoru;
(Niigata-ken, JP) |
Correspondence
Address: |
WENDEROTH, LIND & PONACK, L.L.P.
2033 K STREET N. W.
SUITE 800
WASHINGTON
DC
20006-1021
US
|
Family ID: |
18838693 |
Appl. No.: |
09/998178 |
Filed: |
December 3, 2001 |
Current U.S.
Class: |
473/345 |
Current CPC
Class: |
A63B 53/04 20130101;
A63B 2225/01 20130101; A63B 60/00 20151001; A63B 53/0466 20130101;
A63B 53/0416 20200801; A63B 53/0458 20200801; A63B 2209/00
20130101; A63B 53/0408 20200801 |
Class at
Publication: |
473/345 |
International
Class: |
A63B 053/04 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 4, 2000 |
JP |
2000-368466 |
Claims
What is claimed is:
1. A face structure of a hollow-body, metal golf club head
comprising: a face of laterally elongated shape; a crown and a sole
plate fixed to said face; said face having a thick-walled area of
uniform thickness formed at the backside thereof and thin-walled
areas of uniform thickness formed above and below said thick-walled
area, the thick-walled area extending from the heel side to the toe
side of said face over the hitting area.
2. A face structure of a hollow-body, metal golf club head as
claimed in claim 1, wherein the area of said thick-walled area is
from 30 to 40% of the total area of said face's backside.
3. A face structure of a hollow-body, metal golf club head as
claimed in claim 1, wherein a vertical width of said thick-walled
area is set from 15 mm to 20 mm.
4. A face structure of a hollow-body, metal golf club head as
claimed in claim 1 or 2, wherein an elongated portion for fixing
said crown and said sole plate is formed projecting backward on the
backside periphery of said face.
5. A face structure of a hollow-body, metal golf club head as
claimed in claim 3, wherein an elongated portion for fixing said
crown and said sole plate is formed projecting backward on the
backside periphery of said face.
6. A face structure of a hollow-body, metal golf club head as
claimed in claim 4, wherein said elongated portion has depth of 15
mm to 25 mm.
7. A face structure of a hollow-body, metal golf club head as
claimed in claim 5, wherein said elongated portion has depth of 15
mm to 25 mm.
8. A face structure of a hollow-body, metal golf club head as
claimed in any one of claims 4 to 7, wherein an angle between said
face's backside and said elongated portion is set from over
90.degree. to 100.degree..
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a face structure of a
hollow-body, metal golf club head having a face of a laterally
elongated shape with a crown and a sole plate fixed thereto.
[0003] 2. Description of the Related Art
[0004] Traditionally, wood clubs used to traverse great distances
have employed a hollow-body, metal club head comprised of a face
with a crown and a sole plate welded to its backside. The face has
been variously improved to have higher resilience so as to carry a
ball much farther.
[0005] For example, a high resilience was realized by means of
titanium alloy used as a head material, which has sufficient
strength in order for the face to be thin-walled. This is because
the thinner-walled face makes the backward elastic deflection
.delta. of the face at impact larger, as shown in FIGS. 2B, 2C with
solid line, and therefore it makes the elastic elongation .lambda.
(indicated as .lambda.v, .lambda.h in FIG. 2) of the face,
especially near the back surface, larger as a whole, resulting in
larger total elastic energy Et (as defined in formula (1) below)
accumulated in the face.
Et=.alpha.x(k.times..lambda..sup.2)/2+.beta. (1)
[0006] Here, k is an elastic constant of the face in the direction
of the elastic elongation .lambda., a is a coefficient varying
related to the elastic elongation distribution in the thickness
direction, and .beta. is an elastic energy due to the other
factors.
[0007] On the other hand, in Japanese Patent Laid-open Publication
No. Hei 9-192273, as shown in FIG. 3, a face structure improvement
realizing higher resilience obtained by decreasing a thickness of
an area around a hitting area 23 is proposed. A thin-walled area 25
provided around the hitting area 23 makes not only the hitting area
23 to be of higher strength but also the elastic backward
elongation of the face 21 to be larger in all directions.
[0008] However, since the face has generally longer dimension in a
horizontal direction than in a vertical direction as shown in FIG.
2, even when it has the thin-walled area 25, the elastic elongation
of the face, especially near the face's back surface, is larger
vertically than horizontally at impact. Thus, the elastic energy Ev
due to the vertical elastic elongation .lambda.v is large, and the
energy Eh due to the horizontal elongation .lambda.h is relatively
small. In other words, the total elastic energy Et accumulated in
the face 21 at impact is not distributed equally to the vertical
elastic energy Ev and the horizontal energy Eh.
[0009] Therefore, the carry varies owing to the variation of the
total elastic energy Et resulted from the horizontally or
vertically deviated hits from hitting area 23, namely, the sweet
spot. In other words, the carry of an off-center hit depends not
only on the amount of deviation but on the direction of the
deviation. Thus, the face structure of laterally elongated shape
has tendency of ill stability in a ball carry.
[0010] Furthermore, the ball struck by an off-center hit generally
has spin owing to so-called a gear effect. As shown in FIG. 2, the
ball impact too close to the heel 23a of the face 21 results in
slicing trajectory, and the ball impact too close to the toe 23b
results in hooking. This gear effect works less when the thickness
of the face 21 is smaller. Then the ball trajectory will be stably
straight.
[0011] However the face structure 23 having a thin-walled area 25
around the hitting area 23 as shown in FIG. 3 has undesirable
characteristics in ball trajectory stability especially because it
has thin-walled areas 25a, 25b on both lateral sides of the hitting
area 23. The contact too close to the heel 25a increases a slicing
spin, and the contact close to the toe 25b increases a hooking
spin, due to the gear effect. Accordingly, this type of face
structure is less stable in the ball trajectory of horizontally
off-center contact.
SUMMERY OF THE INVENTION
[0012] In view of the above problems, it is an object of the
present invention to provide a golf club head having a face
structure of laterally elongated shape with thin-walled areas
therein, which realizes good stability of the trajectory both in
distance and in horizontal direction, as well as sufficient
carry.
[0013] In order to accomplish the above and other objects, a face
structure of a hollow-body, metal golf club head according to one
aspect of the present invention comprises a face of laterally
elongated shape, a crown and a sole plate fixed to the face. The
face has a thick-walled area of uniform thickness formed at the
backside thereof, which extends from the heel side to the toe side
thereof over the hitting area, and with thin-walled areas of
uniform thickness formed above and below the thick-walled area.
[0014] The area of the thick-walled area may be from 30 to 40% of
the total area of the face's backside.
[0015] The vertical width of the thick-walled area may be set from
15 mm to 20 mm.
[0016] An elongated portion for fixing the crown and the sole plate
may be formed projecting backward on the backside periphery of the
face.
[0017] The elongated portion may have the depth of 15 mm to 25
mm.
[0018] The angle between the face's backside and the elongated
portion may be set from over 90.degree. to 100.degree..
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1A is an elevation of a face structure of a golf club
head according to one embodiment of the present invention, and
[0020] FIG. 1B is a sectional view taken on the line B-B in the
arrows direction of FIG. 1A;
[0021] FIGS. 2A-2C are the views showing the backward elastic
deflection 6 produced at impact in a conventional face of laterally
elongated shape, the elastic elongation .lambda.v, .lambda.h of the
face, especially of the face's backside. FIG. 2A is an elevational
view in section, FIG. 2B and FIG. 2C are sectional views taken on
B-B and C-C lines respectively in the arrows direction of FIG. 2A;
and
[0022] FIG. 3A is a side sectional view of a conventional
hollow-body, metal golf club head comprising a face which is shaped
laterally elongated provided with a thin-walled area, and FIG. 3B
is a sectional view taken on B-B in the arrows direction of FIG.
3A.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] The preferred embodiments of this invention will be
described in detail with reference to the accompanying drawings.
The basic Japanese Patent Application No. 2000-368466 filed on Dec.
4, 2000, the contents of which is incorporated herein by reference.
FIG. 1 shows a face structure of one embodiment of the present
invention. FIG. 1A is an elevational view thereof and FIG. 1B is a
sectional view taken on the line B-B in the arrows direction of
FIG. 1A.
[0024] As shown in the drawings, a club face 11 in this embodiment
comprises a neck 13 connected to a shaft, a face 15, and a backward
elongated portion 17 projecting from the entire periphery of the
face's backside. These are forged integrally from titanium alloy.
Then a crown and a sole plate (not shown) are welded to the
elongated portion 17 so as to form a hollow-body structured golf
club head.
[0025] The face 15 is shaped laterally elongated, namely, has
longer width horizontally than vertically. A thick-walled area 15a
of uniform vertical width is provided projecting from the backside
of the face 15, which is extending from the heel to the toe side
over a hitting area 16a at the center of the face. The areas above
and below the thick-walled area 15a are thin-walled areas 15b, 15c,
as shown in the drawings. These two thin areas 15b, 15c are of the
same thickness and are of substantially the same area.
[0026] The thickness of the thick-walled area 15a is set at the
appropriate value within 2.3-2.7 mm, and the vertical width thereof
is set appropriately within 15-20 mm. Thus, the area of the
thick-walled area 15a is within 30-40% of the total face backside
area. On the other hand, the thickness of the thin-walled areas
15b, 15c is set at the appropriate value within 1.8-2.2 mm. These
values, namely, the area and thickness of those areas are
determined in order for the elastic energy Ev of the vertical
elastic elongation .lambda.v of the face 15 and the elastic energy
Eh of the horizontal elongation .lambda.h to be sufficiently equal
when an expected load of hitting is imposed at the hitting area
16a. The value of the expected load of hitting is selected
according to the target user of the club. In other words, for a
general club the average value of some amateur golfers may be used,
and for a made-to-order club for particular professional golf
player, his own average value should be used.
[0027] The face 15 of such appropriate values will accumulate
substantially the same amount of elastic energy at horizontally
deviated impact, as the elastic energy at vertically deviated
impact. Thus the variation of carries will be reduced, which was
caused by the directional variation of the deviation of hits.
[0028] The reason that the face structure 15 of this embodiment is
able to sufficiently equalize the elastic energies Eh and Ev, due
to the horizontal and vertical elongations .lambda.h, .lambda.v
respectively, is as follows.
[0029] Since the face 15 has the thick-walled area extending from
the heel to the toe and the thin-walled areas above and below the
thick-walled area, the horizontal elastic constant .lambda.h of the
face 15 is larger than the vertical elastic constant .lambda.v.
This difference between .lambda.h and .lambda.v compensates the
difference between the elastic energies Ev and Eh, namely, (Ev-Eh)
due to the difference between the elastic elongations .lambda.v and
.lambda.h. Thus, the total elastic energy Et accumulated at the
hitting is distributed equally to the energy Eh of horizontal
elongation .lambda.h and to the energy Ev of vertical elongation
.lambda.v.
[0030] Since the thick-walled area 15a is of sufficient,
horizontally uniform thickness, even a contact at areas 16b, 16c,
deviated horizontally from the sweet spot, will not tend to lead to
the gear effect with any spin of the ball. Thus, the trajectory
will stably go straight without increasing slicing or hooking. In
other words, the variation of trajectory direction will be well
reduced.
[0031] The elongated portion 17 is formed projecting backward from
the entire periphery of face backside, and has generally a
cylindrical appearance with the projection projecting 20 mm deep.
The angle D1 which the uppermost portion of the elongated portion
17 forms with the face backside is 100.degree.. The angle
progressively decreases downward and is minimized at the lowest
portion with the angle D2 of 91.degree..
[0032] The crown and the sole plate are welded to the edges 17a,
17b of the projecting elongated portion 17. Since the weld zone is
located apart from the face 15 by the depth of the projection and
defects in welding and/or a heat-affected zone by welding are
prevented, the face 15 will be free from degradation in strength
and toughness therein.
[0033] Moreover, since the angle D which the backside of the face
15 forms with the elongated portion 17 is set to be obtuse under
100.degree., the span between the hitting area 16a and the edge
17a, 17b of the face portion 11 will be relatively large taking the
dimension of the face 15 into consideration. Thus, faster swing
speed of the head and higher resilience of the face are
accomplished by means of little aerodynamic drag against the face
15 and large bending moment by the hitting on the face 15,
respectively. This results in further improvement in a ball
carry.
[0034] The reason why the smallest angle, 91.degree., is small as
compared to the uppermost angle of 100.degree. is that the
aerodynamic drag at the lowest portion, which has maximum swing
speed, should be as small as possible to retard the deceleration of
the head.
[0035] Though this embodiment's face 15, whose thickness is 2.3-2.7
mm even at the thick-walled area, is significantly thinner than the
usual casting titanium alloy face, whose thickness is 2.8-3.0 mm,
it has still sufficient strength. This is because the embodiment's
forged face portion 11 is improved in strength than a conventional
cast face by approximately 20%, and because the face 15 has
relatively high strength and toughness since the crown and the sole
plate are welded to the elongated portion projecting therefrom.
Such thin-walled face structure of this invention has realized
improved resilience and extended carry.
[0036] According to one aspect of the invention, since thin-walled
areas are provided above and below the thick-walled area in the
face, the vertical elastic constant kv of the face is smaller than
the horizontal elastic constant kh. Therefore, as can be understood
with the above-mentioned formula (1), the elastic energy Ev will
become smaller, which results in substantially equal distribution
of the total energy Et into the vertical energy Ev and the
horizontal energy Eh.
[0037] Thus, the variation of the ball distance due to the
variation of direction of deviation from the face center will be
reduced since the face's total elastic energy of horizontally
off-center impact and vertically off-center impact are
substantially the same.
[0038] Moreover, since the thick-walled area, extending from the
heel to the toe, has uniform and sufficient thickness, the gear
effect, due to the horizontally off-center contact, will be
reduced. Thus, the ball will scarcely have spin, and therefore the
trajectory will be stably straight with little slicing or
hooking.
[0039] According to another aspect of the invention, decrease in
durability of the face due to insufficient thick-walled area is
modified since the thick-walled area has over 30% of the total
area, and on the other hand, decrease in the resilience due to the
insufficient thin-walled area is also modified since the
thick-walled area has less than 40% of the total area.
[0040] According to yet another aspect of the invention, since the
vertical width of the thick-walled area is over 15 mm, the face has
greater durability due to the sufficient width being resistant to
strong impact, and additionally, wider area free from gear effect
realizes more stable and straight trajectory. On the other hand,
since the same width is up to 20 mm, good resilience is realized by
modifying the decrease of resilience due to insufficient area of
the thin-walled area.
[0041] According to further aspect of the invention, since the
crown and the sole plate are fixed to the elongated portion, the
fixing portion is apart from the face. Thus, the defects or
weakening of fixing, for example poor welding or thermal
degradation caused by welding, are prevented from being occurred in
the face, resulting in prevention of decrease in strength and
toughness of the face, which requires sufficient impact
resistance.
[0042] Furthermore, as the strength and toughness are improved, the
thickness of the face is able to be smaller so as to realize better
resilience.
[0043] According to another aspect of the invention, since the
elongated portion has the depth of over 15 mm, the fixing zone is
located sufficiently apart from the face. Thus the face will have
sufficient strength and toughness even with poor welding or thermal
degradation in the fixing zone. Additionally, since the elongated
portion has the depth of under 25 mm, this portion is able to be
deep drawn, by presswork or the like, integrally with the face so
as to reduce the manufacturing cost significantly.
[0044] According to further aspect of the invention, since the
angle which the face's backside forms with the elongated portion is
set at obtuse angle under 100.degree., the span between the hitting
area and the edge of the face is large considering the dimension of
the face. Thus, faster swing speed of the head and higher
resilience of the face are accomplished by means of little air
resistance against the face and large bending moment of the face
caused by load of hitting, respectively.
[0045] Having described a specific embodiment of the invention, the
invention should not be taken limitative by any of the details of
the description and various changes and modifications may be made
without departing from the spirit and scope of the invention.
[0046] For example, the upper and lower thin-walled areas may be of
different thickness, though they were equal in the above
embodiment, as long as the elastic energy is equally distributed in
horizontal and vertical directions. When the lower thin-walled area
is thicker, for example, the center of gravity will descend,
resulting in the advantage that the ball will be brought higher
easily.
* * * * *