U.S. patent application number 13/299390 was filed with the patent office on 2012-06-21 for iron golf club set.
Invention is credited to Kenji KII.
Application Number | 20120157222 13/299390 |
Document ID | / |
Family ID | 46235092 |
Filed Date | 2012-06-21 |
United States Patent
Application |
20120157222 |
Kind Code |
A1 |
KII; Kenji |
June 21, 2012 |
IRON GOLF CLUB SET
Abstract
An iron golf club set 2 includes n iron golf clubs. Toe side
sole widths d1 of the clubs are defined as d1(1), d1(2), . . . ,
d1(n) in an ascending order of a real loft angle L1. A maximum
value of the toe side sole widths d1 is defined as d1max. A minimum
value of the toe side sole widths d1 is defined as d1min. Heel side
sole widths d2 of the clubs are defined as d2(1), d2(2), . . . ,
d2(n) in an ascending order of a real loft angle L1. A maximum
value of the heel side sole widths d2 is defined as d2max. A
minimum value of the heel side sole widths d2 is defined as d2min.
The maximum value d1max is substantially equal to the minimum value
d1min. The maximum value d2max is substantially equal to the
minimum value d2min.
Inventors: |
KII; Kenji; (Kobe-shi,
JP) |
Family ID: |
46235092 |
Appl. No.: |
13/299390 |
Filed: |
November 18, 2011 |
Current U.S.
Class: |
473/290 |
Current CPC
Class: |
A63B 53/047 20130101;
A63B 53/0408 20200801; A63B 53/00 20130101; A63B 53/0416 20200801;
A63B 53/005 20200801; A63B 53/0433 20200801; A63B 60/00
20151001 |
Class at
Publication: |
473/290 |
International
Class: |
A63B 53/00 20060101
A63B053/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 15, 2010 |
JP |
2010-278723 |
Claims
1. An iron golf club set comprising n iron golf clubs (n is an
integer equal to or greater than 2), wherein when toe side sole
widths d1 of the clubs are defined as d1(1), d1(2), . . . , d1(n)
in an ascending order of a real loft angle L1 from the club having
the smallest real loft angle L1; a maximum value of the toe side
sole widths d1 is defined as d1max; a minimum value of the toe side
sole widths d1 is defined as d1min; heel side sole widths d2 of the
clubs are defined as d2(1), d2(2), . . . , d2(n) in an ascending
order of a real loft angle L1 from the club having the smallest
real loft angle L1; a maximum value of the heel side sole widths d2
is defined as d2max; a minimum value of the heel side sole widths
d2 is defined as d2min; bounce angles .theta.1 of the clubs are
defined as .theta.1(1), .theta.1(2), . . . , .theta.1(n) in an
ascending order of a real loft angle L1 from the club having the
smallest real loft angle L1; a maximum value of the bounce angles
.theta.1 is defined as .theta.1max; and a minimum value of the
bounce angles .theta.1 is defined as .theta.1min, the iron golf
club set satisfies .theta.1(1).ltoreq..theta.1(2).ltoreq. . . .
.ltoreq..theta.1(n); the maximum value d1max is substantially equal
to the minimum value d1min; and the maximum value d2max is
substantially equal to the minimum value d2min.
2. The iron golf club set according to claim 1, wherein a
difference (d1max-d1min) is equal to or less than 1.0 mm; and a
difference (d2max-d2min) is equal to or less than 1.0 mm.
3. The iron golf club set according to claim 2, wherein the iron
golf club set satisfies d1(1).ltoreq.d1(2).ltoreq. . . .
.ltoreq.d1(n), and d2(1).ltoreq.d2(2).ltoreq. . . .
.ltoreq.d2(n).
4. The iron golf club set according to claim 2, wherein iron golf
club set satisfies d1(1).gtoreq.d1(2).gtoreq. . . . d1(n), and
d2(1).gtoreq.d2(2).gtoreq. . . . .gtoreq.d2(n).
5. The iron golf club set according to claim 2, wherein the
difference (d1max-d1min) is equal to or less than 0.8 mm; and the
difference (d2max-d2min) is equal to or less than 0.8 mm.
6. The iron golf club set according to claim 1, wherein the iron
golf club set satisfies .theta.1(1)<.theta.1(n).
7. The iron golf club set according to claim 6, wherein the iron
golf club set satisfies .theta.1(1)<.theta.1(2)< . . .
<.theta.1(n).
8. The iron golf club set according to claim 1, wherein a ratio
(d1/d2) is 0.75 or greater and 2.5 or less in all iron numbers.
Description
[0001] The present application claims priority on Patent
Application No. 2010-278723 filed in JAPAN on Dec. 15, 2010, the
entire contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an iron golf club set
having a plurality of iron type golf clubs.
[0004] 2. Description of the Related Art
[0005] An iron golf club set having a plurality of iron type golf
clubs is commercially available. Usually, the club set includes a
plurality of clubs having different real loft angles, lie angles,
and lengths. Each of the clubs constituting the set is
distinguished by an iron number. Specification of a head is
determined for every iron number based on various respects.
[0006] Japanese Utility Model Application Publication (JP-Y) No.
7-49970 discloses an iron golf club set. In the iron golf club set,
a sole width on a long iron club side with a 5-iron or a 6-iron as
a boundary is formed to be sequentially greater as an iron number
becomes smaller, and a sole width on a short iron side is formed to
be sequentially greater as an iron number becomes greater.
SUMMARY OF THE INVENTION
[0007] The present inventor considered optimization of a sole width
in an iron set from a respect different from that of the
conventional technique. As a result, the present inventor attained
specification of the sole width capable of exhibiting an effect
different from that of the conventional technique.
[0008] It is an object of the present invention to provide a golf
club set capable of appropriately exhibiting a function required
for each of iron numbers.
[0009] A club set according to the present invention includes n
iron golf clubs (n is an integer equal to or greater than 2). Toe
side sole widths d1 of the clubs are defined as d1(1), d1(2), . . .
, d1(n) in an ascending order of a real loft angle L1 from the club
having the smallest real loft angle L1. A maximum value of the toe
side sole widths d1 is defined as d1max. A minimum value of the toe
side sole widths d1 is defined as d1min. Heel side sole widths d2
of the clubs are defined as d2(1), d2(2), . . . , d2(n) in an
ascending order of a real loft angle L1 from the club having the
smallest real loft angle L1. A maximum value of the heel side sole
widths d2 is defined as d2max. A minimum value of the heel side
sole widths d2 is defined as d2min. Bounce angles .theta.1 of the
clubs are defined as .theta.1(1), .theta.1(2), . . . , .theta.1(n)
in an ascending order of a real loft angle L1 from the club having
the smallest real loft angle L1. A maximum value of the bounce
angles .theta.1 is defined as .theta.1max. A minimum value of the
bounce angles .theta.1 is defined as .theta.1min. At this time, the
club set satisfies .theta.1(1).ltoreq..theta.1(2).ltoreq. . . .
.theta.1(n). The maximum value d1max is substantially equal to the
minimum value d1min. The maximum value d2max is substantially equal
to the minimum value d2min.
[0010] Preferably, a difference (d1max-d1min) is equal to or less
than 1.0 mm. Preferably, a difference (d2max-d2min) is equal to or
less than 1.0 mm.
[0011] In a preferred aspect, the club set satisfies
d1(1).ltoreq.d1(2).ltoreq. . . . .ltoreq.d1(n), and
d2(1).ltoreq.d2(2).ltoreq. . . . d2(n).
[0012] In another preferred aspect, the club set satisfies
d1(1).gtoreq.d1(2).gtoreq. . . . .gtoreq.d1(n), and
d2(1).gtoreq.d2(2).gtoreq. . . . .gtoreq.d2(n).
[0013] Preferably, the difference (d1max-d1min) is equal to or less
than 0.8 mm. Preferably, the difference (d2max-d2min) is equal to
or less than 0.8 mm.
[0014] The iron golf club set can appropriately exhibit the
function required for each of the iron numbers.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 shows a golf club set according to one embodiment of
the present invention;
[0016] FIG. 2 shows a perspective view of a head used in the set of
FIG. 1;
[0017] FIG. 3 shows a front view and bottom view of the head of
FIG. 2;
[0018] FIG. 4 shows a cross sectional view taken along line F4-F4
of FIG. 3;
[0019] FIG. 5 shows a cross sectional view taken along line F5-F5
of FIG. 3; and
[0020] FIG. 6 shows a cross sectional view taken along line F6-F6
of FIG. 3.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0021] Hereinafter, the present invention will be described in
detail based on preferred embodiments with appropriate references
to the drawings.
[0022] A golf club set 2 shown in FIG. 1 is an iron golf club set.
A real loft angle L1 of the iron type golf club is usually 15
degrees or greater and 70 degrees or less.
[0023] The club set 2 includes a plurality of iron type golf clubs
4 having different real loft angles L1. The golf club set 2 has
eight golf clubs 4. The number of the clubs of the golf club set 2
is equal to or greater than 2. In respect of emphasizing an effect
of the present invention, the number n of the clubs is preferably
equal to or greater than 3, more preferably equal to or greater
than 5, and particularly preferably equal to or greater than 6. In
the golf rule, the number of the clubs capable of being used during
play is restricted. In this respect, the number n of the clubs is
preferably equal to or less than 12, more preferably equal to or
less than 11, and still more preferably equal to or less than
10.
[0024] Each of the golf clubs 4 has a shaft sf, a head hd, and a
grip gp. The head hd is mounted to a tip part of the shaft sf. The
grip gp is mounted to a back end part of the shaft sf.
[0025] The eight golf clubs 4 are a first golf club c1, a second
golf club c2, a third golf club c3, a fourth golf club c4, a fifth
golf club c5, a sixth golf club c6, a seventh golf club c7, and an
eighth golf club c8 in an ascending order of a real loft angle L1
from the club having the smallest real loft angle L1. The lower an
iron number is, the smaller the real loft angle L1 of the head hd
is.
[0026] The first golf club c1 has a shaft sf1, a head hd1, and a
grip gp. The second golf club c2 has a shaft sf2, a head hd2, and a
grip gp. The third golf club c3 has a shaft sf3, a head hd3, and a
grip gp. The fourth golf club c4 has a shaft sf4, a head hd4, and a
grip gp. The fifth golf club c5 has a shaft sf5, a head hd5, and a
grip gp. The sixth golf club c6 has a shaft sf6, a head hd6, and a
grip gp. The seventh golf club c7 has a shaft sf7, a head hd7, and
a grip gp. The eighth golf club c8 has a shaft sf8, a head hd8, and
a grip gp.
[0027] The golf clubs 4 constituting the golf club set 2 have
different club lengths. The golf clubs 4 are the first golf club
c1, the second golf club c2, the third golf club c3, the fourth
golf club c4, the fifth golf club c5, the sixth golf club c6, the
seventh golf club c7, and the eighth golf club c8 in an order from
the club having the longest club length. The lower the iron number
is, the longer the club length is. The club length is mainly
adjusted by the length of the shaft sf. The golf clubs 4 having the
same length may be included.
[0028] Although not shown in the drawings, the golf clubs 4
constituting the golf club set 2 have different lie angles. The
golf clubs 4 are the first golf club c1, the second golf club c2,
the third golf club c3, the fourth golf club c4, the fifth golf
club c5, the sixth golf club c6, the seventh golf club c7, and the
eighth golf club c8 in an ascending order of a lie angle from the
club having the smallest lie angle. The lower the iron number is,
the smaller the lie angle is. The golf clubs 4 having the same lie
angle may be included.
[0029] In the embodiment of FIG. 1, the first golf club c1 is a
4-iron. The second golf club c2 is a 5-iron. The third golf club c3
is a 6-iron. The fourth golf club c4 is a 7-iron. The fifth golf
club c5 is an 8-iron. The sixth golf club c6 is a 9-iron. The
seventh golf club c7 is a pitching wedge (PW). The eighth golf club
c8 is an approach wedge (AW). In the present invention, the iron
numbers of the golf clubs 4 included in the golf club set 2 are not
restricted.
[0030] FIG. 2 shows a perspective view of the head hd2 of the golf
club c2 (5-iron). FIG. 3 shows a front view and bottom view of the
head hd2. In FIG. 3, the front view is drawn on the upper side, and
the bottom view is drawn on the lower side. Hereinafter, the head
hd2 is described as an example. Structures of heads having the
other iron numbers are the same as that of the head hd2.
[0031] The head hd2 has a face 5, a hosel 6 and a sole 7. The golf
club head hd has a shaft hole 10 to which a shaft is mounted. The
shaft hole 10 is formed in the hosel 6.
[0032] Materials of the head hd2 and face 5 are not restricted. The
face 5 may be a metal, or may be a nonmetal. Examples of the metal
include iron, stainless steel, maraging steel, pure titanium, and a
titanium alloy. Examples of the iron include soft iron (a low
carbon steel having a carbon content of less than 0.3 wt %).
Examples of the nonmetal include carbon fiber reinforced plastic
(CFRP).
[0033] The head hd2 has a plurality of face grooves gv. The face
grooves gv are merely also referred to as grooves. A formation
method of the face grooves gv is not restricted. Examples of the
formation method of the face grooves gv include forging, press
processing, casting, and cut processing (carving).
[0034] A part of the face 5 is subjected to treatment for adjusting
a surface roughness. The typical example of the treatment is
shot-blasting treatment. Boundary lines k1 between an area which is
subjected to the shot-blasting treatment and an area which is not
subjected to the shot-blasting treatment are shown in FIGS. 2 and
3. The boundary lines k1 are a toe side boundary line k1t and a
heel side boundary line k1h. An area between the toe side boundary
line k1t and the heel side boundary line k1h is subjected to the
shot-blasting treatment. All the face grooves gv are formed in the
area which is subjected to the shot-blasting treatment. A toe side
area relative to the toe side boundary line k1t is not subjected to
the shot-blasting treatment. A heel side area relative to the heel
side boundary line k1h is not subjected to the shot-blasting
treatment. The toe side boundary line kit and the heel side
boundary line k1h are visually recognized by the absence or
presence of the shot-blasting treatment. The surface roughness is
increased by the shot-blasting treatment. The increased surface
roughness can increase a backspin rate of a ball. The increase in
the backspin rate tends to stop the ball near the point of fall.
The increase in the backspin rate can facilitate the stopping of
the ball at the aiming point. The increase in the backspin rate is
particularly useful for a shot targeting a green and an approach
shot. As shown in FIGS. 2 and 3, the boundary layer k1t and the
boundary layer k1h are substantially parallel.
[0035] The face 5 has a land area LA. The land area LA indicates a
portion on which the grooves are not formed, of a surface of the
face 5 (face surface). If minute unevenness formed by the
shot-blasting treatment or the like is disregarded, the land area
LA is substantially a plane.
[0036] FIG. 4 shows a cross sectional view taken along line F4-F4
of FIG. 3. A position of the line F4-F4 in a toe-heel direction
bisects a distance between a measurement position of a toe side
sole width d1 and a measurement position of a heel side sole width
d2 (see FIG. 3). A recess part 12 is formed on a back side of the
head hd2. The head hd2 is a cavity back type.
[0037] As shown in FIG. 4, the head hd2 has a head body 14 and a
face plate 16. The head body 14 has an opening (not shown)
corresponding to a shape of the face plate 16. The face plate 16 is
fitted into the opening. A contour line 18 of the face plate 16 is
drawn in FIG. 3.
[Real Loft Angle L1 of Each of Clubs]
[0038] The real loft angles L1 of the golf clubs 4 constituting the
golf club set 2 are defined as L1(1), L1(2), . . . , L1(n) in an
ascending order from the club having the smallest real loft angle
L1. In the set 2, the greater the iron number is, the greater the
real loft angle L1 is. That is, the set 2 satisfies
L1(1)<L1(2)< . . . <L1(n).
[0039] The golf club set 2 includes golf clubs 4 having a real loft
angle L1 equal to or less than 40 degrees and golf clubs 4 having a
real loft angle L1 greater than 40 degrees. In the golf club set 2,
the golf clubs 4 having a real loft angle L1 equal to or less than
40 degrees are a 9-iron and clubs (a 4-iron to an 8-iron) having a
real loft angle L1 smaller than that of the 9-iron. Another
examples of the clubs having a real loft angle L1 equal to or
smaller than 40 degrees include a 3-iron, a 2-iron, a 1-iron. In
the golf club set 2, the golf clubs 4 having a real loft angle L1
greater than 40 degrees are a pitching wedge and an approach wedge.
Another examples of the clubs having a real loft angle L1 greater
than 40 degrees include a sand wedge and a lob wedge.
[0040] The golf club set 2 includes a golf club having a real loft
angle L1 equal to or greater than 50 degrees. The golf club 4
having the real loft angle L1 equal to or greater than 50 degrees
is an approach wedge. Another examples of the clubs having a real
loft angle L1 of equal to or greater than 50 degrees include a sand
wedge and a lob wedge.
[0041] A difference between real loft angles L1 of adjacent iron
numbers, that is, [L1(m)-L1(m-1)] is usually 2 degrees or greater
and 6 degrees or less.
[Measurement Position of Toe Side Sole Width d1]
[0042] In the present application, a toe side sole width d1 is
defined. A measurement position of the width d1 in a toe-heel
direction is a toe side end of the face groove gv (see FIG. 3).
[Measurement Position of Heel Side Sole Width d2]
[0043] In the present application, a heel side sole width d2 is
defined. A measurement position of the width d2 in a toe-heel
direction is a heel side end of the face groove gv (see FIG.
3).
[Measuring Method of Sole Width d1]
[0044] FIG. 5 shows a cross sectional view taken along line F5-F5
of FIG. 3. FIG. 5 shows a cross sectional view of the toe side end
of the face groove gv. The section is perpendicular to the face
surface. The sole width d1 is determined based on a contour line
PL1 of the section. In the contour line PL1, a face side end point
p1 of the sole 7 is determined. Furthermore, in the contour line
PL1, a back side end point b1 of the sole 7 is determined. A
distance in a face-back direction between the end point p1 and the
end point b1 is the sole width d1.
[0045] The end point p1 is a forefront point of the contour line
PL1.
[0046] The endpoint b1 is defined as follows. When a curvature
radius of the contour line PL1 is scanned toward the back side from
the center side of the sole 7, a position where the curvature
radius is first equal to or less than 10.0 mm is defined as the end
point b1.
[Measuring Method of Sole Width d2]
[0047] FIG. 6 shows a cross sectional view taken along line F6-F6
of FIG. 3. The section is perpendicular to the face surface. A sole
width d2 is determined based on a contour line PL2 of the section.
In the contour line PL2, a face side end point p2 of the sole 7 is
determined. Furthermore, in the contour line PL2, a backside
endpoint b2 of the sole 7 is determined. A distance in a face-back
direction between the end point p2 and the end point b2 is the sole
width d2.
[0048] The end point p2 is a forefront point of the contour line
PL2.
[0049] The end point b2 is defined as follows. When a curvature
radius of the contour line PL2 is scanned toward the back side from
the center side of the sole 7, a position where the curvature
radius is first equal to or less than 10.0 mm is defined as the end
point b2.
[0050] In the present application, the toe side sole widths d1 of
the plurality of clubs constituting the set are defined as d1(1),
d1(2), . . . , d1(n) in an ascending order of a real loft angle L1
from the club having the smallest real loft angle L1. A maximum
value of the toe side sole widths d1 is defined as d1max, and a
minimum value of the toe side sole widths d1 is defined as
d1min.
[0051] For example, in the embodiment of FIG. 1 described above,
the toe side sole width d1(1) is a toe side sole width d1 of the
4-iron. The toe side sole width d1(2) is a toe side sole width d1
of the 5-iron. The toe side sole width d1(3) is a toe side sole
width d1 of the 6-iron. The toe side sole width d1(4) is a toe side
sole width d1 of the 7-iron. The toe side sole width d1(5) is a toe
side sole width d1 of the 8-iron. The toe side sole width d1(6) is
a toe side sole width d1 of the 9-iron. The toe side sole width
d1(7) is a toe side sole width d1 of the pitching wedge. The toe
side sole width d1(8) is a toe side sole width d1 of the approach
wedge.
[0052] In the present application, the heel side sole widths d2 of
the plurality of clubs constituting the set are defined as d2(1),
d2(2), . . . , d2(n) in an ascending order of a real loft angle L1
from the club having the smallest real loft angle L1. A maximum
value of the heel side sole widths d2 is defined as d2max, and a
minimum value of the heel side sole widths d2 is defined as
d2min.
[0053] For example, in the embodiment of FIG. 1 described above,
the heel side sole width d2(1) is a heel side sole width d2 of the
4-iron. The heel side sole width d2(2) is a heel side sole width d2
of the 5-iron. The heel side sole width d2(3) is a heel side sole
width d2 of the 6-iron. The heel side sole width d2(4) is a heel
side sole width d2 of the 7-iron. The heel side sole width d2(5) is
a heel side sole width d2 of the 8-iron. The heel side sole width
d2(6) is a heel side sole width d2 of the 9-iron. The heel side
sole width d2(7) is a heel side sole width d2 of the pitching
wedge. The heel side sole width d2(8) is a heel side sole width d2
of the approach wedge.
[0054] In the present application, bounce angles .theta.1 of the
plurality of clubs constituting the set are defined as .theta.1(1),
.theta.1(2), . . . , .theta.1(n) in an ascending order of a real
loft angle L1 from the club having the smallest real loft angle L1.
A maximum value of the bounce angles .theta.1 is defined as
.theta.1max, and a minimum value of the bounce angles .theta.1 is
defined as .theta.1min.
[0055] For example, in the embodiment of FIG. 1 described above,
the bounce angle .theta.1(1) is a bounce angle .theta.1 of the
4-iron. The bounce angle .theta.1(2) is a bounce angle .theta.1 of
the 5-iron. The bounce angle .theta.1(3) is a bounce angle .theta.1
of the 6-iron. The bounce angle .theta.1(4) is a bounce angle
.theta.1 of the 7-iron. The bounce angle .theta.1(5) is a bounce
angle .theta.1 of the 8-iron. The bounce angle .theta.1(6) is a
bounce angle .theta.1 of the 9-iron. The bounce angle .theta.1(7)
is a bounce angle .theta.1 of the pitching wedge. The bounce angle
.theta.1(8) is a bounce angle .theta.1 of the approach wedge.
[Measurement Position of Bounce Angle .theta.1]
[0056] In the present application, a measurement position of the
bounce angle .theta.1 in the toe-heel direction is a position dv1
bisecting a distance between a measurement position of the toe side
sole width d1 and a measurement position of the heel side sole
width d2 (see FIG. 3).
[Measuring Method of Bounce Angle .theta.1]
[0057] FIG. 4 shows a cross sectional view taken along line F4-F4
of FIG. 3. The section is perpendicular to the face surface. The
bounce angle .theta.1 is determined based on a contour line PL3 of
the section. In the contour line PL3, a face side endpoint p3 of
the sole 7 is determined. Furthermore, in the contour line PL3, a
back side endpoint b3 of the sole 7 is determined. A distance in a
face-back direction between the end point p3 and the end point b3
is a sole width dc.
[0058] The end point p3 is a forefront point of the contour line
PL3.
[0059] The end point b3 is defined as follows. When a curvature
radius of the contour line PL3 is scanned toward the back side from
the center side of the sole 7, a position where the curvature
radius is first equal to or less than 10.0 mm is defined as the end
point b3.
[0060] A center point Cp is at a position bisecting a distance
between the end point p3 and the end point b3 in the face-back
direction (see FIG. 4). An angle between a tangent line TL1 of the
contour line PL3 at the center point Cp and a level surface h is
the bounce angle .theta.1. The bounce angle .theta.1 is measured in
a head of a base condition. The base condition will be described
later.
[0061] Preferably, the bounce angle .theta.1 (degree) satisfies
.theta.1(1).ltoreq..theta.1(2).ltoreq. . . .
.ltoreq..theta.1(n).
[0062] Preferably, the maximum value d1max is substantially equal
to the minimum value d1min. The term "substantially equal" means
that (d1max-d1min)/d1max is equal to or less than 0.08.
[0063] Preferably, the maximum value d2max is substantially equal
to the minimum value d2min. The term "substantially equal" means
that (d2max-d2min)/d2max is equal to or less than 0.08.
[0064] Preferably, a difference (d1max-d1min) is equal to or less
than 1.0 mm. More preferably, the difference (d1max-d1min) is equal
to or less than 0.8 mm. Still more preferably, the difference
(d1max-d1min) is equal to or less than 0.5 mm. Preferably, a lower
limit value is equal to or greater than 0 mm, and may be equal to
or greater than 0.1 mm in respect of a dimensional error.
[0065] Preferably, a difference (d2max-d2min) is equal to or less
than 1.0 mm. The difference (d2max-d2min) is more preferably equal
to or less than 0.8 mm. The difference (d2max-d2min) is still more
preferably equal to or less than 0.5 mm. Preferably, a lower limit
value is equal to or greater than 0 mm, and may be equal to or
greater than 0.1 mm in respect of a dimensional error.
[0066] It was found that novel effects can be produced by
suppressing the difference (d1max-d1min) and the difference
(d2max-d2min).
[0067] A conventional iron set has the following specification A or
specification B.
[0068] [Specification A]: The greater an iron number is, the wider
a sole width is. In other words, the smaller the iron number is,
the narrower the sole width is.
[0069] [Specification B]: The smaller an iron number is, the wider
a sole width is. In other words, the greater the iron number is,
the narrower the sole width is.
[0070] In the specification A, a sole width of a long iron is
narrow, and a sole width of a short iron is wide. On the other
hand, in the specification B, a sole width of a long iron is wide,
and a sole width of a short iron is narrow. A usual iron set has
the specification A.
[0071] In the club set, in order to unify a swing balance, the
greater the iron number is, the greater a head weight is.
Therefore, in the specification B, the smaller the iron number is,
the wider the sole width is, and the smaller the head weight is. In
this case, in a head having a small iron number, a head weight is
small, and weight distribution to a sole is great. Therefore, a
weight distributed to a portion other than the sole is small, and a
degree of freedom of weight distribution is small. For this reason,
a degree of freedom of head design of a head having a small iron
number (particularly, a long iron) is small. For example, designs
for a position of a center of gravity, a head dimension, and a
moment of inertia or the like is constrained.
[0072] Since the difference (d1max-d1min) and the difference
(d2max-d2min) are restricted in the club set of the embodiment, the
constraint of the head having a small iron number to the head
design is eased.
[0073] The short iron usually tends to be swung with a downward
blow. Therefore, influences of a ground on the sole of the short
iron are great. When the sole width of the short iron is too wide,
ground resistance is excessive, and operativity is apt to be lost.
When the sole width of the short iron is too wide, good swinging
through is hard to obtain.
[0074] Since the difference (d1max-d1min) and the difference
(d2max-d2min) are restricted in the club set of the embodiment, a
sole width of a short iron having a great iron number is not
excessive. Therefore, operativity of the short iron is good, and
swinging through is good. The term "good swinging through" means
that resistance from the ground is low to be likely to swing a club
through.
[0075] The long iron usually tends to be swung with a level blow.
Therefore, the sole of the long iron is preferably slid on the
ground, to hit a ball. When the sole width of the long iron is too
narrow, the ball is apt to be duffed.
[0076] Since the difference (d1max-d1min) and the difference
(d2max-d2min) are restricted in the club set of the embodiment, a
sole width of a head having a small iron number is not excessively
small. Therefore, the duffing of the long iron is suppressed.
[0077] Since the long iron has a long club length and has a small
loft, the long iron finds it difficult to hit the ball well. A long
iron having a narrow sole width projects an image of thrusting of
the long iron into the ground. The long iron having a narrow sole
width projects an image of liable duffing. These negative images
are apt to induce a misshot. In the embodiment, the sole width of
the long iron having a small iron number is not excessively small.
Therefore, the misshot can be decreased.
[0078] Since the long iron has a small loft in the first place, a
height of a suitable trajectory is hard to obtain. In addition, the
long iron having a narrow sole width has a high position of a
center of gravity. The high position of a center of gravity causes
a low trajectory. In the embodiment, the sole width of the long
iron having a small iron number is not excessively small.
Therefore, the height of the suitable trajectory tends to be
obtained.
[0079] Many golf players place a sole surface on a ground (lawn) at
address. The stability of the head at address is also referred to
as "sitting". The head having stable sitting tends to be stably
addressed. When fluctuation between the sittings of the iron
numbers is small, the direction of the face at address tends to be
stabilized between the iron numbers.
[0080] It was found that a difference between the sittings of the
different iron numbers is decreased by restricting the difference
(d1max-d1min) and the difference (d2max-d2min). For this reason,
the direction of the head at address tends to be stabilized. In the
head of the embodiment, the face tends to be addressed toward a
target in all the iron numbers. It was found that the stability of
the sitting causes small variation in hitting directions between
different iron numbers.
[0081] When a change in the bounce angle and a change in the sole
width are overlapped, the difference between the sittings of the
different iron numbers may be increased. Even when the bounce angle
is changed in the heads of the embodiment, the variation in the
sittings between the iron numbers can be suppressed.
[0082] In the iron set, "performance flow" is important. The term
"performance flow" is performance continuousness between the
different iron numbers. Examples of the performance include a
flight distance, a trajectory, and a backspin rate. In the iron
set, it is preferable that the performance of the club having each
of the iron numbers is gradually changed with a change in the iron
number. In the iron set, performance suitable for each of the iron
numbers tends to be obtained. The iron set having good performance
flow facilitates selection of the suitable iron number performed by
the golf players. In contrast, it is not preferable that the
performance of a certain iron number is projected or a direction of
a change in the performance is reversed. The iron set having poor
performance flow complicates selection of the suitable iron number
performed by the golf players.
[0083] Conventionally, in respect of improving the performance
flow, it was considered that the sole width is preferably changed
with a change in the iron number. However, a change in the sole
width and a change in the other specification (a loft angle, a head
weight, a club length, a bounce angle, or a position of a center of
gravity or the like) are cooperated with each other, and thereby a
change in the performance between the adjacent iron numbers tends
to be excessive. The excessive change in the performance between
the adjacent iron numbers is hardly caused by suppressing the
change in the sole width. The club set having good performance flow
tends to be obtained by suppressing the change in the sole
width.
[0084] In respect of the performance flow, a preferable club set
satisfies the following formulae (f1) and (f2) or the following
formulae (f3) and (f4).
d1(1).ltoreq.d1(2).ltoreq. . . . .ltoreq.d1(n) (f1)
d2(1).ltoreq.d2(2).ltoreq. . . . d2(n) (f2)
d1(1).gtoreq.d1(2).gtoreq. . . . d1(n) (f3)
d2(1).gtoreq.d2(2).gtoreq. . . . d2(n) (f4)
[0085] In respects of suppressing the duffing of the club having a
small iron number and of improving the operativity of the club
having a great iron number, the bounce angle .theta.1 (degree)
preferably satisfies the following formula (f5), more preferably
the following formula (f6), and still more preferably the following
formula (f7).
.theta.1(1).ltoreq..theta.1(2).ltoreq. . . . .theta.1(n) (f5)
.theta.1(1)<.theta.1(n) (f6)
.theta.1(1)<.theta.1(2)< . . . <.theta.1(n) (f7)
[0086] The toe side sole width d1 is not restricted. In respect of
suppressing the duffing of the long iron, the toe side sole width
d1 is preferably equal to or greater than 18 mm, more preferably
equal to or greater than 20 mm, and still more preferably equal to
or greater than 23 mm. In respect of the operativity of the short
iron, the toe side sole width d1 is preferably equal to or less
than 30 mm, more preferably equal to or less than 28 mm, and still
more preferably equal to or less than 25 mm.
[0087] The heel side sole width d2 is not restricted. In respect of
suppressing the duffing of the long iron, the heel side sole width
d2 is preferably equal to or greater than 12 mm, more preferably
equal to or greater than 14 mm, and still more preferably equal to
or greater than 17 mm. In respect of the operativity of the short
iron, the heel side sole width d2 is preferably equal to or less
than 24 mm, more preferably equal to or less than 22 mm, and still
more preferably equal to or less than 19 mm.
[0088] A ratio (d1/d2) is not restricted. In respects of
suppressing excessive weight distribution to a heel portion and of
avoiding an extremely short distance of a center of gravity, the
ratio (d1/d2) is preferably equal to or greater than 0.75, more
preferably equal to or greater than 1.0, and still more preferably
equal to or greater than 1.2. In respects of suppressing excessive
weight distribution to a toe portion and of avoiding an extremely
long distance of a center of gravity, the ratio (d1/d2) is
preferably equal to or less than 2.5, more preferably equal to or
less than 2.0, and still more preferably equal to or less than 1.5.
These preferable ratios (d1/d2) are preferably satisfied in all the
iron numbers. The distance of a center of gravity is a distance
between a shaft axis line and a center of gravity of a head.
[0089] When the sole width of the long iron is too great, a back
side of a sole part can be visually recognized at address. In this
case, concentration to the face surface at address may be declined,
or an uncomfortable feeling may be produced. In this respect, the
heads having all the iron numbers preferably satisfies the follow
item (a).
[0090] (a) In a toe-heel direction range in which the face surface
exists, a top surface of the head is located on the most back
side.
[0091] When the item (a) is satisfied, the back side of the sole
part cannot be viewed at address. Therefore, the concentration to
the face surface is facilitated, and the uncomfortable feeling is
small. The definitions of a base condition, toe-heel direction, and
face-back direction are as follows. The item "back side" described
above is judged according to the face-back direction.
[Base Condition]
[0092] The base condition is a state where the head is placed on
the level surface h at a predetermined lie angle and real loft
angle. In more detail, the base condition is the following state. A
center axis line z of a shaft hole of a head is provided in an
optional vertical surface VP1. The head is grounded on the level
surface h in a state where the center axis line z is inclined to
the level surface h at a lie angle, and the face surface is
inclined to the vertical surface VP1 at a real loft angle (see FIG.
4). The vertical surface VP1 is a plane parallel to a vertical
line.
[Toe-Heel Direction]
[0093] In the head of the base condition, a direction parallel to
an intersection line between the vertical surface VP1 and the level
surface h is the toe-heel direction.
[Face-Back Direction]
[0094] A direction perpendicular to the toe-heel direction and
parallel to the level surface h is the face-back direction.
EXAMPLES
[0095] Hereinafter, the effects of the present invention will be
clarified by examples. However, the present invention should not be
interpreted in a limited way based on the description of the
examples.
[0096] Hereinafter, a test was performed using a set having three
clubs.
Example 1
[0097] Stainless steel was cast, to obtain non-polished heads. Face
grooves were formed by cut processing. A sole width and a bounce
angle were adjusted by polishing, to obtain heads of example 1.
Heads of a 4-iron, 7-iron, and pitching wedge were produced. In all
the iron numbers, a sole width between a toe position (a
measurement position of a sole width d1) and a heel position (a
measurement position of a sole width d2) was gradually narrowed
toward a heel side.
[0098] A shaft suitable for each of the iron numbers was bonded to
each of the heads. "NS PRO 950S" (trade name) manufactured by
Nippon Shaft Co., Ltd. was used as the shaft. Grips were mounted to
the shafts, to obtain golf clubs according to example 1. A length
of the 4-iron was set to 38.5 inches. A length of the 7-iron was
set to 37.0 inches. A length of the pitching wedge was set to 35.5
inches.
Examples 2 and 3
[0099] The non-polished head obtained in the example 1 was used. A
sole width and a bounce angle were adjusted by polishing. Heads
according to examples 2 and 3 were obtained in the same manner as
in the example 1. In both the examples 2 and 3, in all iron
numbers, a sole width between a toe position (a measurement
position of a sole width d1) and a heel position (a measurement
position of a sole width d2) was gradually narrowed toward a heel
side.
[0100] The same shaft and grip as those of the example 1 were
mounted, to obtain golf clubs according to examples 2 and 3.
Comparative Examples 1 and 2
[0101] The non-polished head obtained in the example 1 was used. A
sole width and a bounce angle were adjusted by polishing. Heads
according to comparative examples 1 and 2 were obtained in the same
manner as in the example 1. In both the comparative examples 1 and
2, in all the iron numbers, a sole width between a toe position (a
measurement position of a sole width d1) and a heel position (a
measurement position of a sole width d2) was gradually narrowed
toward a heel side.
[0102] The same shaft and grip as those of the example 1 were
mounted, to obtain golf clubs according to comparative examples 1
and 2.
[0103] Valuation methods are as follows.
[Goodness of Swinging Through]
[0104] Ten golf players having a handicap of 0 or greater and 10 or
less placed balls on a semi-rough, and actually hit the balls, to
evaluate goodness of swinging through. "SRIXON Z-STAR" (trade name)
manufactured by SRI Sports Limited was used as the ball. The
evaluation is sensuous evaluation. Each of the golf players made
five-stage evaluation on a scale of one to five. The score of five
is the maximum evaluation, and the score of one is the minimum
evaluation. The lower the score is, the lower the evaluation is.
The average of the ten golf players' evaluation scores is shown in
the following Table 1.
[Ease to Address]
[0105] The ten golf players simultaneously evaluated goodness of
swinging through and ease to address. The evaluation is sensuous
evaluation. Each of the golf players made five-stage evaluation on
a scale of one to five. The score of five is the maximum
evaluation, and the score of one is the minimum evaluation. The
lower the score is, the lower the evaluation is. The average of the
ten golf players' evaluation scores is shown in the following Table
1.
[Deviation in Hitting Direction]
[0106] The ten golf players placed balls on a fairway, and hit the
balls toward a target. Each of the golf players hit five balls
using each of iron numbers. "SRIXON Z-STAR" (trade name)
manufactured by SRI Sports Limited was used as the ball. A
deviation distance (yard) from the target direction was measured.
The deviation distance is a distance between a straight line
connecting a hitting point to a target point and a final arrival
point of the hit ball. The deviation distance was a positive value
both in the case where the ball was deviated to a right side and in
the case where the ball was deviated to a left side. The average of
the ten golf players' measurement values is shown in the following
Table 1. Each of the ten golf players is a type to ground a sole
surface to address the golf club.
[Hitting Directivity in Set]
[0107] A maximum width of deviation in a hitting direction
synthesizing three iron numbers was defined as hitting directivity.
The hitting directivity was evaluated in four stages of very good,
good, average, and poor. These meanings are as follows.
[0108] Very Good: Variation in a hitting direction as a whole set
is equal to or less than 5 yards.
[0109] Good: Variation in a hitting direction as a whole set is
greater than 5 yards and equal to or less than 10 yards.
[0110] Average: Variation in a hitting direction as a whole set is
greater than 10 yards and equal to or less than 15 yards.
[0111] Poor: Variation in a hitting direction as a whole set is
greater than 15 yards.
[0112] The variation in the hitting direction as the whole set was
calculated using the test data of the above-mentioned [deviation in
hitting direction]. However, the deviation distance was defined as
plus when the ball was deviated to a right side. The deviation
distance was defined as minus when the ball was deviated to a left
side. The average value of the ten golf players' deviation
distances was calculated for every iron number. When a maximum
value of the deviation distances of the three iron numbers was
defined as D1, and a minimum value of the deviation distances of
the three iron numbers was defined as D2, a difference (D1-D2) was
defined as "variation in a hitting direction as a whole set".
TABLE-US-00001 TABLE 1 specifications and evaluation results of
examples and comparative examples Example Example Example
Comparative Comparative 1 2 3 example 1 example 2 4-iron Sole width
d1 (mm) 24.5 24.0 25.0 30.5 20.0 Sole width d2 (mm) 16.5 16.0 17.0
21.0 17.0 Bounce angle .theta.1 1.0 1.0 1.0 0.0 0.1 (degree) Head
weight (g) 249.0 247.2 250.8 246.8 239.8 Goodness of swinging 4.0
4.1 3.6 1.8 3.7 through Ease to address 4.2 4.0 3.9 3.0 1.5
Deviation in hitting 10.8 11.1 10.6 13.6 18.6 direction (yard)
7-iron Sole width d1 (mm) 24.5 24.5 24.5 28.7 21.0 Sole width d2
(mm) 16.5 16.5 16.5 19.9 16.0 Bounce angle .theta.1 3.0 3.0 3.0 2.2
1.1 (degree) Head weight (g) 270.0 270.0 270.0 266.9 263.9 Goodness
of swinging 4.1 4.2 3.7 2.8 3.6 through Ease to address 4.0 4.0 3.9
3.9 2.8 Deviation in hitting 8.6 9.0 8.8 10.1 16.9 direction (yard)
PW Sole width d1 (mm) 24.5 25.0 24.0 24.1 23.4 Sole width d2 (mm)
16.5 17.0 16.0 18.0 14.8 Bounce angle .theta.1 5.0 5.0 5.0 7.8 5.8
(degree) Head weight (g) 294.0 295.7 293.1 290.8 288.9 Goodness of
swinging 3.9 3.6 4.0 4.0 3.2 through Ease to address 3.7 4.2 3.8
1.5 1.4 Deviation in hitting 7.7 8.2 8.0 9.5 8.7 direction (yard)
Hitting directivity in set Very Good Good Average Poor Good
[0113] Since fluctuation in sittings between the iron numbers was
small in the examples, the variation in the hitting direction was
small. Since a difference between the sittings of the iron numbers
was small in the examples, evaluation of ease to address was high
in all the iron numbers.
[0114] As shown in Table 1, the examples are highly evaluated as
compared with the comparative examples. From the results, the
advantages of the present invention are apparent.
[0115] The present invention can be applied to all golf club sets.
The description hereinabove is merely for an illustrative example,
and various modifications can be made in the scope not to depart
from the principles of the present invention.
* * * * *