U.S. patent application number 13/050392 was filed with the patent office on 2011-11-03 for golf club head.
This patent application is currently assigned to BRIDGESTONE SPORTS CO., LTD. Invention is credited to Wataru BAN, Masaomi HIRUTA.
Application Number | 20110269567 13/050392 |
Document ID | / |
Family ID | 44858666 |
Filed Date | 2011-11-03 |
United States Patent
Application |
20110269567 |
Kind Code |
A1 |
BAN; Wataru ; et
al. |
November 3, 2011 |
GOLF CLUB HEAD
Abstract
This invention provides a golf club head in which a plurality of
scorelines are formed in its face surface. The golf club head
includes a first fine groove formed in the face surface to extend
parallel to the scorelines, and a second fine groove formed in the
face surface to intersect with the first fine groove.
Inventors: |
BAN; Wataru; (Chichibu-shi,
JP) ; HIRUTA; Masaomi; (Shinagawa-ku, JP) |
Assignee: |
BRIDGESTONE SPORTS CO., LTD
Tokyo
JP
|
Family ID: |
44858666 |
Appl. No.: |
13/050392 |
Filed: |
March 17, 2011 |
Current U.S.
Class: |
473/331 |
Current CPC
Class: |
A63B 53/0466 20130101;
A63B 53/0445 20200801; A63B 53/047 20130101 |
Class at
Publication: |
473/331 |
International
Class: |
A63B 53/04 20060101
A63B053/04 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 30, 2010 |
JP |
2010-105955 |
Claims
1. A golf club head comprising: a plurality of scorelines are
formed in a face surface thereof; a first fine groove formed in the
face surface to extend parallel to the scorelines; and a second
fine groove formed in the face surface to intersect with said first
fine groove.
2. The head according to claim 1, wherein a plurality of said first
fine grooves are formed between adjacent scorelines to align
themselves in a direction perpendicular to the scorelines, a
plurality of said second fine grooves are formed, and each of said
first fine grooves formed between the adjacent scorelines
intersects with at least one of said second fine grooves.
3. The head according to claim 1, wherein a plurality of said first
fine grooves are formed between adjacent scorelines to align
themselves in a direction perpendicular to the scorelines, a
plurality of said second fine grooves are formed, and at least one
of said second fine grooves intersects with not less than two of
said first fine grooves formed between the adjacent scorelines.
4. The head according to claim 1, wherein said second fine groove
is formed from an edge of the scoreline.
5. The head according to claim 1, wherein said first fine groove
and said second fine groove are formed by one of cutting and laser
processing.
6. The head according to claim 1, wherein said first fine groove
has a ridged edge.
7. The head according to claim 1, wherein an intersection angle
between said first fine groove and said second fine groove is
20.degree. (inclusive) to 90.degree. (inclusive).
8. The head according to claim 1, wherein said first fine groove
and said second fine groove have different depths.
9. The head according to claim 1, wherein depths of said first fine
groove and said second fine groove are 5 .mu.m (inclusive) to 25
.mu.m (inclusive).
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a golf club head.
[0003] 2. Description of the Related Art
[0004] In general, a plurality of parallel linear grooves are
formed in the face surface of a golf club head to extend in the
toe-to-heel direction. These grooves are called, for example,
scorelines, marking lines, or face lines (they will be referred to
as scorelines in this specification). These scorelines have an
effect of increasing the back spin amount on a struck golf ball, or
suppressing a significant decrease in back spin amount on a struck
golf ball upon a shot in rainy weather or that from the rough.
[0005] Unfortunately, the use of only the scorelines has limits of
increasing the back spin amount and of suppressing a decrease in
back spin amount. Under the circumstance, techniques of forming
grooves finer than the scorelines in the face surface have been
proposed (for example, Japanese Patent Laid-Open No. 2007-202633).
These fine grooves are effective in preventing a decrease in back
spin amount on a struck golf ball.
[0006] However, the grooves finer than the scorelines are readily
filled with water droplets because they are finer than the
scorelines. Hence, these grooves often cannot satisfactorily
exhibit an effect of suppressing a decrease in back spin amount
upon a shot in rainy weather or that from the rough.
SUMMARY OF THE INVENTION
[0007] It is an object of the present invention to improve an
effect of suppressing a decrease in back spin amount by grooves
finer than scorelines.
[0008] According to the present invention, there is provided a golf
club head comprising: a plurality of scorelines are formed in a
face surface thereof; a first fine groove formed in the face
surface to extend parallel to the scorelines; and a second fine
groove formed in the face surface to intersect with the first fine
groove.
[0009] Further features of the present invention will become
apparent from the following description of exemplary embodiments
with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 shows an external view of a golf club head 1 and a
partial enlarged view of a face surface 10 according to an
embodiment of the present invention;
[0011] FIG. 2 is a partial sectional perspective view of the face
surface 10;
[0012] FIG. 3A is a sectional view of a scoreline 20 taken in a
direction perpendicular to its longitudinal direction (the
toe-to-heel direction);
[0013] FIG. 3B is a sectional view of a fine groove 30 taken in a
direction perpendicular to its longitudinal direction;
[0014] FIG. 3C is a sectional view of a fine groove 30 in another
example taken in a direction perpendicular to its longitudinal
direction;
[0015] FIG. 4 is a sectional view showing a primary shaped product
1' before fine grooves 30 to 32 are formed;
[0016] FIG. 5 is a view for explaining a method of forming fine
grooves 30 by an NC milling machine; and
[0017] FIG. 6 is a partial sectional perspective view of a face
surface 10, which shows another example of the fine grooves 31.
DESCRIPTION OF THE EMBODIMENTS
First Embodiment
[0018] FIG. 1 shows an external view of a golf club head 1 and a
partial enlarged view of a face surface 10 according to an
embodiment of the present invention. FIG. 1 illustrates an example
in which the present invention is applied to an iron type golf club
head. The present invention is suitable for an iron type golf club
head and, more particularly, for middle iron, short iron, and wedge
type golf club heads. More specifically, the present invention is
suitable for a golf club head with a loft angle of 30.degree.
(inclusive) to 70.degree. (inclusive) and a head weight of 240 g
(inclusive) to 320 g (inclusive). However, the present invention is
also applicable to wood type and utility (hybrid) type golf club
heads.
[0019] The golf club head 1 has a plurality of scorelines 20 formed
in its face surface (striking surface) 10. The scorelines 20 are
parallel linear grooves extending in the toe-to-heel direction.
Also, the face surface 10 has a plurality of fine grooves 30, 31,
and 32 formed in it.
[0020] The fine grooves 30 are linear grooves which have a width
and depth smaller than the scorelines 20 and extend parallel to the
scorelines 20 in the toe-to-heel direction. That the grooves 30 and
scorelines 20 are parallel to each other includes a case in which
the intersection angle between their infinite extension lines is
0.degree. (inclusive) to 20.degree. (inclusive) for giving an
allowance for, for example, manufacturing errors.
[0021] In this embodiment, the plurality of fine grooves 30 are
formed to align themselves in a direction d1 perpendicular to the
longitudinal direction of the scorelines 20. The fine groove 30
preferably has a length equal to or longer than that of the
scoreline 20 nearest to it. Although each fine groove 30 is one
continuous groove in this embodiment, some or all of them may be
intermittent grooves.
[0022] The fine grooves 31 and 32 have a width and depth smaller
than the scorelines 20 and intersect with the fine grooves 30. In
this embodiment, the fine grooves 31 and 32 are linear grooves.
[0023] FIG. 2 is a partial sectional perspective view of the face
surface 10, FIG. 3A is a sectional view of the scoreline 20 in a
direction perpendicular to its longitudinal direction (the
toe-to-heel direction), and FIG. 3B is a sectional view of the fine
groove 30 taken in a direction perpendicular to its longitudinal
direction. The scorelines 20 will be described first.
[0024] In this embodiment, the scorelines 20 are formed at an equal
pitch, and have uniform cross-sectional shapes throughout their
entire longitudinal portions except for their two ends. Also, the
scorelines 20 have the same cross-sectional shape. Moreover, in
this embodiment, the cross-sectional shape of the scoreline 20 is
symmetrical about the center line in the widthwise direction.
Although the cross-sectional shape of the scoreline 20 is a
trapezoidal shape in this embodiment, it may be another shape such
as a V shape.
[0025] The scoreline 20 has a pair of side walls 21 and a bottom
wall 22. An edge 23 of the scoreline 20 is the boundary portion
between the side wall 21 and the face surface 10. Although a
rounded portion is formed on the edge 23, a configuration in which
no rounded portion is formed on the edge 23 can also be
adopted.
[0026] The fine grooves 30 are formed to extend parallel to the
scorelines 20, and therefore increase the back spin amount on a
struck golf ball. Although the cross-sectional shape of the fine
groove 30 is a semicircular shape, as shown in FIG. 3B, in this
embodiment, it may be another shape such as a trapezoidal shape or
a V shape. A width W of the fine groove 30 is preferably, for
example, 30 .mu.m (inclusive) to 600 .mu.m (inclusive). The smaller
a depth D of the fine groove 30, the smaller the amount of increase
in back spin amount, whereas the larger the depth D, the more a
struck ball is likely to be scratched. Also, the roughness of the
face surface of an athletic golf club head has a predetermined
limit defined by a maximum height (Ry) of 25 .mu.m or less. Hence,
when the golf club head 1 is to be used for athletic purposes, the
depth D is preferably 5 .mu.m (inclusive) to 25 .mu.m
(inclusive).
[0027] The fine grooves 31 and 32 intersect with the fine grooves
30, and function as water channels for draining water which
collects in the fine grooves 30. Hence, the water having collected
in the fine grooves 30 drains into the fine grooves 31 and 32 or
drains into another fine groove 30, in which the water has not yet
collected, via the fine grooves 31 and 32. Upon draining water
which collects in the fine grooves 30, an effect of increasing the
back spin amount on a struck golf ball by the fine grooves 30 is
sustained. This improves an effect of suppressing a decrease in
back spin amount in, for example, rainy weather.
[0028] Water which collects in the fine grooves 30 flows out and
drains into the fine grooves 31 and 32 by means of a pressure
generated by a ball at the time of impact. The fine grooves 31 and
32 are preferably vertically formed from the viewpoint of draining
water not only by the pressure acting at the time of impact but
also by its self weight. Because the fine grooves 30 horizontally
extend at the time of a shot, the intersection angles between the
fine grooves 31 and 32 and the fine groove 30 are preferably about
90.degree. and, for example, 75.degree. (inclusive) to 105.degree.
(inclusive) from the viewpoint of the drainage performance
alone.
[0029] On the other hand, the fine grooves 31 and 32 can not only
function as drainage channels but also exhibit a function of
increasing the back spin amount on a struck golf ball. As the fine
grooves 31 and 32 become more exactly parallel to the fine grooves
30, the back spin amount more greatly increases. Hence, the
intersection angles between the fine grooves 31 and 32 and the fine
groove 30 are preferably about 20.degree. and, for example,
5.degree. (inclusive) to 35.degree. (inclusive) from the viewpoint
of the back spin amount alone.
[0030] Considering both the drainage performance and the back spin
amount, however, the intersection angles between the fine grooves
31 and 32 and the fine groove 30 are preferably 20.degree.
(inclusive) to 90.degree. (inclusive).
[0031] In this embodiment, the fine grooves 31 and 32 have
different lengths, the fine groove 31 intersects with four fine
grooves 30, and the fine groove 32 intersects with two fine grooves
30. Although fine grooves of two types: the fine grooves 31 and 32
with different lengths are formed as fine grooves which intersect
with the fine grooves 30 in the foregoing way in this embodiment,
fine grooves of one or three or more types may be formed. In either
case, each fine groove 30 preferably intersects with at least one
fine groove. Also, as in this embodiment, upon making one fine
groove 31 and one fine groove 32 intersect with a plurality of fine
grooves 30, the water having collected in the fine grooves 30 can
drain into another fine groove 30, in which the water has not yet
collected, via the fine grooves 31 or 32, thus enhancing the
drainage efficiency. At least one fine groove which intersects with
the fine groove 30 preferably intersects with the plurality of fine
grooves 30.
[0032] The cross-sectional shapes, widths, and depths of the fine
grooves 31 and 32 may be the same as or different from those of the
fine groove 30. Especially in accordance with the purpose of use,
the fine grooves 31 and 32 can have a depth different from that of
the fine groove 30. For example, when an increase in back spin
amount is of prime importance, the fine groove 30 is formed deeper
than the fine grooves 31 and 32 to allow a ball to more
satisfactorily bite into the face surface 10. Also, to reduce the
difference in back spin amount due to factors associated with water
droplets between clear weather and rainy weather, the fine grooves
31 and 32 are formed deeper than the fine groove 30 to enhance the
drainage performance.
[0033] In this embodiment, the fine grooves 30 to 32 are formed in
the same pattern for each interval between adjacent scorelines 20.
This produces an effect of suppressing the occurrence of a
variation in back spin amount depending on the position of a
striking point. Note that the roughness of the face surface of an
athletic golf club head has a predetermined limit defined by a
maximum height (Ry) of 25 .mu.m or less and an arithmetic average
roughness of 4.57 .mu.m or less. Hence, when the golf club head 1
is to be used for athletic purposes, the fine grooves 30 to 32 are
designed to comply with this surface roughness rule.
[0034] A method of forming scorelines 20 and fine grooves 30 to 32
will be described next. Scorelines 20 can be formed by, for
example, forging, molding, cutting, or laser processing. Fine
grooves 30 to 32 can be formed by, for example, cutting or laser
processing. The fine grooves 30 and the fine grooves 31 and 32
which intersect with them may be formed by adopting different
processing methods.
[0035] A case in which scorelines 20 are formed by forging and fine
grooves 30 to 32 are formed by milling will be described herein
with reference to FIGS. 4 and 5. FIG. 4 is a sectional view showing
a primary shaped product 1' before fine grooves 30 to 32 are
formed, and FIG. 5 is a view for explaining a method of forming
fine grooves 30 to 32 by an NC milling machine.
[0036] First, a primary shaped product 1' of a golf club head 1, in
which scorelines 20 are formed by forging, is fabricated, as shown
in FIG. 4. In the primary shaped product 1', no fine grooves 30 to
32 are formed in a surface 10' corresponding to the face surface
10.
[0037] Next, fine grooves 30 are formed by milling. The primary
shaped product 1' in which no fine grooves 30 are formed is fixed
to an NC milling machine via a jig 2, as shown in FIG. 5. Although
the face surface 10 is shaped integrally with the golf club head 1
in this embodiment, a face member which forms the face surface 10
and the head body may be provided as separate members and bonded to
each other.
[0038] The NC milling machine includes a spindle 4 which is
rotationally driven about the Z-axis, and a cutting tool (end mill)
5 attached to the lower end of the spindle 4. The distal end shape
of the cutting tool 5 conforms to the cross-sectional shape of the
fine groove 30.
[0039] After the plane coordinates of the face surface 10 are set
on the NC milling machine, the spindle 4 is rotationally driven to
cut the face surface 10 while relatively moving the face surface 10
(primary shaped product 1') or the cutting tool 5 in the direction
to form fine grooves 30. When one fine groove 30 is formed in the
face surface 10, the cutting tool 5 is separated from the face
surface 10. After that, the cutting tool 5 is relatively moved in
the direction in which fine grooves 30 are aligned to form the next
fine groove 30, thereby sequentially forming fine grooves 30. Fine
grooves 31 and 32 can also be formed in the same way.
[0040] When the fine grooves 30 to 32 are formed in the face
surface 10, it is often the case that the face surface 10 becomes
more likely to wear out. To prevent this, after the formation of
the fine grooves 30 to 32, a surface treatment for hardening the
face surface 10 is preferably performed. Examples of such a surface
treatment include carburizing, nitriding, soft nitriding, PVD
(Physical Vapor Deposition), ion plating, diamond-like carbon
coating, and plating. Especially a surface treatment which modifies
a surface without forming another metal layer on the surface, such
as carburizing or nitriding, is preferable.
Second Embodiment
[0041] The back spin amount can further be increased by ridging the
edge of a fine groove 30. FIG. 3C is a sectional view of the fine
groove 30 in this embodiment. The edge of the fine groove 30 has a
ridged portion 30a formed on it to be ridged, so a ball more
satisfactorily bites into the fine groove 30, thereby making it
possible to further increase the back spin amount. For example,
when the fine groove 30 is formed by laser processing, the ridged
portion 30a can be spontaneously formed by this processing. Also,
when the fine groove 30 is formed by cutting, the ridged portion
30a can be formed as a burr by relatively coarse cutting.
Third Embodiment
[0042] Fine grooves which intersect with fine grooves 30 may be
formed from edges 23 of scorelines 20. FIG. 6 is a partial
sectional perspective view of a face surface 10, which shows
another example of the fine grooves 31. In the example shown in
FIG. 6, fine grooves 31 are formed from the edges 23 of the
scorelines 20. Upon forming the fine grooves 31 from the edges 23,
the scorelines 20 and the fine grooves 31 communicate with each
other. Hence, the water in the fine grooves 31 can drain into the
scorelines 20, thereby making it possible to further improve the
drainage performance of the fine grooves 30.
Other Embodiments
[0043] Although a plurality of embodiments of the present invention
have been described above, they can be combined with each other, as
a matter of course.
[0044] 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.
[0045] This application claims the benefit of Japanese Patent
Application No. 2010-105955, filed Apr. 30, 2010, which is hereby
incorporated by reference herein in its entirety.
* * * * *