U.S. patent application number 11/861515 was filed with the patent office on 2009-03-26 for method of manufacturing golf club head and golf club head.
This patent application is currently assigned to BRIDGESTONE SPORTS CO., LTD.. Invention is credited to Wataru Ban, Fumiaki Sato.
Application Number | 20090082129 11/861515 |
Document ID | / |
Family ID | 40472273 |
Filed Date | 2009-03-26 |
United States Patent
Application |
20090082129 |
Kind Code |
A1 |
Ban; Wataru ; et
al. |
March 26, 2009 |
Method of Manufacturing Golf Club Head and Golf Club Head
Abstract
According to this invention, there is provided a method of
manufacturing a golf cub head having a plurality of score lines on
the face. The method of this invention includes the first forming
step of forming grooves for the score lines on the face, and the
second forming step of forming notches uniformly along the
longitudinal direction of the grooves by cutting into the edges of
the grooves formed in the first forming step, the notches having
first side surfaces leading to the face and second side surfaces
leading to the first side surfaces and side surfaces of the
grooves.
Inventors: |
Ban; Wataru; (Chichibu-shi,
JP) ; Sato; Fumiaki; (Chichibu-shi, 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: |
40472273 |
Appl. No.: |
11/861515 |
Filed: |
September 26, 2007 |
Current U.S.
Class: |
473/331 ;
29/558 |
Current CPC
Class: |
A63B 60/00 20151001;
A63B 53/0445 20200801; A63B 53/0466 20130101; A63B 53/04 20130101;
Y10T 29/49996 20150115; A63B 53/047 20130101; A63B 53/0408
20200801 |
Class at
Publication: |
473/331 ;
29/558 |
International
Class: |
A63B 53/04 20060101
A63B053/04 |
Claims
1. A method of manufacturing a golf club head having a plurality of
score lines on a face, comprising: a first forming step of forming
grooves for the score lines on the face; and a second forming step
of forming notches at both edges of the grooves uniformly along the
longitudinal direction of the grooves by cutting into the edges,
the notches having first side surfaces leading to the face and
second side surfaces leading to the first side surfaces and side
surfaces of the grooves.
2. The method according to claim 1, wherein in the second forming
step, the notches are formed by cutting the edges of the grooves by
a cutting tool while the face or the cutting tool relatively moves
in a direction of forming the score lines.
3. The method according to claim 1, wherein an angle between the
plane of the side surface of the groove and the plane of the face
is not greater than 80 degrees.
4. The method according to claim 3, wherein an angle between the
plane of the first surface and the plane of the face is greater
than 50 degrees and not greater than 90 degrees.
5. The method according to claim 1, wherein a length of a
perpendicular line from the intersection point of the first side
surface and the second side surface of the notch to the side
surface of the groove is not greater than 0.1 mm.
6. A golf club head having a plurality of score lines on a face,
wherein the score lines are formed by first forming grooves for the
score lines on the face and forming notches at both edges of the
grooves uniformly along the longitudinal direction of the grooves
by cutting into the edges, the notches having first side surfaces
leading to the face and second side surfaces leading to the first
side surfaces and side surfaces of the grooves.
7. A golf club head having a plurality of score lines on a face,
wherein the score lines include notches formed at both edges of the
score lines uniformly along the longitudinal direction of the score
lines, the notches having first side surfaces leading to the face
and second side surfaces leading to the first side surfaces and
side surfaces of the score lines.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a golf club head and, more
particularly, to score lines on the face.
[0003] 2. Description of the Related Art
[0004] Generally, on the face of a golf club head, a plurality of
straight grooves are formed parallel to each other in the
toe-and-heel direction (e.g., Japanese Patent Laid-Open Nos.
10-248974 and 2005-169129). These grooves are called score lines,
marking lines, face lines, or the like (to be referred to as score
lines in this specification). These score lines have an effect of
increasing the back spin amount or suppressing a significant
decrease in back spin amount of a shot in a case of a rainy day or
a shot from rough. As a method of forming score lines, for example,
cutting, forging, or casting is used.
[0005] The width of a score line is narrow and, for example, that
of a score line of a golf club head for competitions is determined
to be 0.9 mm or less by the rule. It is not always easy to form a
plurality of score lines to be straight and parallel to each other.
For example, when forming score lines by cutting, the score lines
may be slightly distorted due to the shake or wear of a cutting
tool or distortion of the material of the face. In case of forging,
score lines may be slightly distorted due to the influence of
distortion of the material of the face. In case of casting, score
lines may be slightly distorted due to shrinkage. When score lines
are distorted, their outer appearance becomes poor. In addition,
individual difference in performance between the products may
occur.
SUMMARY OF THE INVENTION
[0006] It is an object of the present invention to provide a golf
club head having score lines with little distortion.
[0007] According to the present invention, there is provided a
method of manufacturing a golf club head having a plurality of
score lines on a face, comprising a first forming step of forming
grooves for the score lines on the face, and a second forming step
of forming notches uniformly along the longitudinal direction of
the grooves by cutting into the edges of the grooves formed in the
first forming step, the notches having first side surfaces leading
to the face and second side surfaces leading to the first side
surfaces and side surfaces of the grooves.
[0008] In the present invention, the grooves are formed in the
first forming step, and the notches are formed by cutting into the
edges of the grooves in the second forming step 1 thereby forming
score lines having the notches. Since only the edges of the grooves
are cut in the second forming step, the cut amount can be small.
Accordingly, the shake or wear of a cutting tool or distortion of
the material of the face is small, and therefore machining with a
higher accuracy is possible. For the outer appearance or
performance of the score lines which is influenced by the boundary
portions of the score lines and face, since the notches which form
the boundary portions can be machined with a higher accuracy in the
second forming step, the machining accuracy of the score lines
substantially increases. Therefore, a golf club head having score
lines with little distortion can be provided.
[0009] According to the present invention, there is provided a golf
club head having a plurality of score lines on a face, wherein the
score lines are formed by first forming grooves for the score lines
and forming notches uniformly along the longitudinal direction of
the grooves by cutting into the edges of the grooves, the notches
having first side surfaces leading to the face and second side
surfaces leading to the first side surfaces and side surfaces of
the grooves.
[0010] According to the present invention, there is provided a golf
club head having a plurality of score lines on a face, wherein the
score lines include notches formed at both edges of the score lines
uniformly along the longitudinal direction of the grooves, the
notches having first side surfaces leading to the face and second
side surfaces leading to the first side surfaces and side surfaces
of the grooves.
[0011] Other features of the present invention will become apparent
from the following description of an exemplary embodiment with
reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a view showing the outer appearance of a golf club
head 1 according to an embodiment of the present invention;
[0013] FIG. 2 shows a sectional view of a score line 20 in a
direction perpendicular to the longitudinal direction (toe-and-heel
direction), and its partially enlarged view;
[0014] FIG. 3A is a schematic view illustrating an example of a
case in which a first formed groove is cut by an NC milling
machine;
[0015] FIG. 3B is a view showing an example of the sectional shape
of a first formed groove 20' formed in the first forming step;
[0016] FIG. 4A is a view illustrating a machining example of a case
in which a cutting tool 4a is used which simultaneously machines
notches 21 at both edges of the first formed groove 20';
[0017] FIG. 48 is a view illustrating a machining example of a case
in which the notch 21 is machined by relatively inclining the
rotation axis Z of a cutting tool 4b with respect to the face
10;
[0018] FIG. 5A shows tables of the measurement data of the score
lines of an example of the present invention;
[0019] FIG. 5B shows tables of the measurement data of the score
lines of a comparative example; and
[0020] FIG. 6 is a table showing the measurement results of the
actual measurement values of the groove widths (groove widths W1 in
FIG. 2) of the score lines and the evaluations of the
machinabilities and test shot results obtained when the edge angle
(angle .theta.2 in FIG. 3B) of the first formed groove, a notch
angle .theta.1 (FIG. 2), and a distance D (FIG. 2) changed.
DESCRIPTION OF THE EMBODIMENTS
[0021] FIG. 1 is a view showing the outer appearance of a golf club
head 1 according to an embodiment of the present invention. FIG. 1
shows an example in which the present invention is applied to an
iron golf club head. The present invention is suitable for short
iron golf club heads and wedge iron golf club heads, e.g., golf
club heads with a loft angle of 409 to 70.degree. (both inclusive)
and a head weight of 260 g to 320 g (both inclusive). However, the
present invention is also applicable to wood or hybrid golf club
heads.
[0022] The golf club head 1 has a plurality of score lines 20
formed on its face 10. The respective score lines 20 are straight
grooves extending in the toe-and-heel direction and parallel to
each other. In this: embodiment, the respective score lines 20 are
arranged at regular intervals (same pitch) but they may be arranged
at irregular intervals. FIG. 2 shows a sectional view of the score
line 20 in a direction perpendicular to the longitudinal direction
(toe-and-heel direction), and its partially enlarged view. In this
embodiment, the sectional shapes of the score lines 20 are the same
except in two end portions in the longitudinal direction. The score
lines 20 have the same sectional shape.
[0023] In this embodiment, the sectional shape of the score line 20
is an almost trapezoid. However, the sectional shape of the score
line 20 is not limited to this, and may be an almost square or
triangle. In this embodiment, the sectional shape of the score line
20 is symmetric. Notches 21 having a V-shaped cross section are
formed in the edges (boundary portions with the face 10) of the
score line 20 uniformly along its longitudinal direction.
[0024] The notch 21 has a side surface 21a leading to the face 10
and a side surface 21b leading to the side surface 21a and a side
surface (excluding the notch 21) 20a of the score line 20. Both the
side surfaces 21a and 21b are flat. A point P1 is the intersection
point of the side surfaces 21a and 21b. The intersection point P1
may be rounded. The angle between the side surfaces 21a and 21b is,
e.g., 90.degree. (inclusive) to 180.degree. (exclusive) and
preferably 90.degree. to 135.degree. (both inclusive). The widths
of the side surfaces 21a and 21b may be the same, or may be
different from each other.
[0025] The side surface 21a of the notch 21 and the face 10 form an
angle .theta.1. The angle .theta.1 influences a friction force
between a golf ball and the face 10 which is produced upon a shot.
When the notch 21 is formed so as to increase the angle .theta.1,
the back spin amount of a golf ball can increase, but the golf ball
is easily damaged. Conversely, when the notch 21 is formed so as to
decrease the angle .theta.1, the back spin amount of a golf ball
decreases, however, damage to the ball can be prevented. A distance
D represents the length of the normal from the intersection point
P1 to the side surface 20a of the score line 20. As the distance D
increases, the cut amount for forming the notch 21 increases.
[0026] The method of forming the score lines 20 will be described
next. In this embodiment, upon forming the score lines 20, grooves
for the score lines 20 are first formed on the face 10 (first
forming step). These grooves will be referred to as first formed
grooves, hereinafter. The edges of the first formed grooves are cut
so as to form the notches 21 (second forming step), thereby
finishing the score lines 20.
[0027] Upon cutting for forming the notches 21, an NC (numerically
controlled) milling machine can be used to perform cutting with a
higher accuracy. The first formed grooves may be formed by, e.g.,
any of cutting, forging, and casting. Since the notches 21 are
formed after the first formed grooves, cutting is desirable.
Particularly when the notches 21 are formed using an NC milling
machine, it is desirable to cut the first formed grooves by using
the same NC milling machine. A case in which the same NC milling
machine is continuously used to form the first formed grooves and
the notches 21 will be described below.
[0028] FIG. 3A is a schematic view illustrating an example of a
case in which a first formed groove is cut using an NC milling
machine. A golf club head 1' without the score lines 20 is fixed to
the NC milling machine via a jig 2. Note that in this embodiment, a
case in which the face 10 is integrally formed with the golf club
head is described. However, a face member which forms the face 10
and the head body may be prepared as separated members and joined
together. In this case, the face member is fixed to the NC milling
machine to form the score lines 20.
[0029] The NC milling machine includes a spindle 3 which is
rotatably driven around the axis Z. A cutting tool (end mill) 4 is
attached to the lower end of the spindle 3. After setting the plane
coordinates of the face 10 in the NC milling machine, the spindle 3
is rotatably driven. The face 10 (golf club head 1') or cutting
tool 4 is moved relatively in a formation direction d1 of the score
lines 20 to mill the face 10, thereby forming a first formed
groove. When one first formed groove has been formed, the cutting
tool 4 is separated from the face 10. After that, the cutting tool
4 is moved relatively in a direction perpendicular to the formation
direction d1 of the score lines 20, and the next first formed
groove is formed. In this manner, the first formed grooves are
sequentially formed. The positions of the respective first formed
grooves are numerically controlled in accordance with design data.
FIG. 38 is a view showing an example of the sectional shape of a
first formed groove 20' formed in the first forming step.
[0030] When all the first formed grooves have been formed, the
notches 21 are then machined. At this time, the cutting tool 4 is
changed as needed. FIG. 4A illustrates a machining example of a
case in which a cutting tool 4a is used which simultaneously
machines the notches 21 at both edges of the first formed groove
20'. FIG. 4B illustrates a machining example of a case in which the
notch 21 is machined by relatively inclining the rotation axis Z of
a cutting tool 4b with respect to the face 10. In this case, it is
required to use an NC milling machine which can adjust the relative
inclination angle of the rotation axis Z with respect to the face
10. In either case, the sectional shape of the notch 21 depends on
the distal shape of the cutting tools 4a or 4b. The angle .theta.1
in FIG. 2 depends on the distal shape of the cutting tool 4a or 4b
and the cutting position.
[0031] Each notch 21 is formed by moving the face 10 (golf club
head 1') or cutting tool 4a or 4b relatively in the formation
direction d1 (FIG. 3A) of the score lines 20, as in the case of the
first formed groove 20', so as to mill the edge of the first formed
groove 20'. The positions of the respective notches 21 are
numerically controlled in accordance with design data. When the
notches 21 have been completely formed, the score lines 20 having
the sectional shape shown in FIG. 2 are completely formed. Note
that after that, the surface of the face 10 may be cut as the
surface finish of the face 10.
[0032] In this embodiment, as described above, the first formed
grooves 20' are formed, and then the notches 21 are formed by
cutting into the edges of the first formed grooves 20', thereby
forming the score lines 20 having the notches 21. In forming the
notches 21, since only the edges of the machined first formed
groove 20' are cut, the cut amount can be small. Accordingly, the
shake or wear of the cutting tool or distortion of the material of
the face 10 is small, and therefore machining with a higher
accuracy is possible. For the outer appearance or performance of
the score lines 20 which is influenced by the boundary portions of
the score lines 20 and face 10, since the notches 21 which form the
boundary portions can be machined with a higher accuracy, the
machining accuracy of the score lines 20 substantially increases.
Therefore, the golf club head 1 having the score lines 20 with
little distortion can be provided. As a secondary effect, the back
spin amount of the golf ball and its susceptibility to damage can
be adjusted by the degree of the angle .theta.1 in FIG. 2.
EXAMPLES
[0033] FIG. 5A shows the measurement data of the score lines of an
example of the present invention, and FIG. 5B shows the measurement
data of the score lines of a comparative example. For the score
lines of the example, first formed grooves and notches were formed
using an NC milling machine. The groove depth of the first formed
groove was set to 0.45 mm (design value); the edge angle (angle
.theta.2 in FIG. 3B), 60.degree. (design value); and the groove
width (W2 in FIG. 3B), 0.8 mm. The notch angle .theta.1 (see FIG.
2) was set to 70.degree. (design value); and the distance D (see
FIG. 2), 0.05 mm (design value). The score lines of the comparative
example were formed by casting such that they had no portion
corresponding to the notch of the example (the same shape as the
first formed groove of the example). The groove depth of the score
line of the comparative example was set to 0.45 mm (design value);
the edge angle, 60.degree. (design value); and the groove width,
0.7 mm (design value).
[0034] In FIGS. 5A and 5B, "groove width and measurement position
(mm)" indicates the actual measurement values of the groove widths
at a plurality of positions on the score line, which is the groove
width W1 in FIG. 2 for the example. In this embodiment, three score
lines were set as measurement targets. Each of 0 and .+-.1 to .+-.4
indicates the measurement position. A phantom line (line L1 in FIG.
1), which passes the point of contact of the golf club head with
the ground upon soling the golf club head and is perpendicular to
the score lines, is set as a reference (measurement position=0).
The positions away from the line L1 toward the toe side are denoted
by sign -, and those away from the line L1 toward the heel side are
denoted by sign .+-.. For example, "+1" indicates a position which
is shifted from the line L1 by 1 mm toward the heel side, and "-2"
indicates a position shifted from the line L1 by 2 mm toward the
toe side.
[0035] A standard deviation (same groove) indicates the standard
deviation of the groove widths at the respective positions on the
same score line, and a standard deviation average value (same
groove) indicates the average value of the standard deviations
(same groove) of four score lines. An error range (same groove)
indicates the difference between the maximum value and minimum
value of the groove widths at the respective positions on the same
score line, and an error range average value (same groove)
indicates the average value of the error ranges (same groove) of
four score lines.
[0036] A standard deviation (between grooves) indicates the
standard deviation of the groove widths at the same position on the
respective score lines, and a standard deviation average value
(between grooves) indicates the average value of the standard
deviations (same groove) of all the measurement positions. An error
range (between grooves) indicates the difference between the
maximum value and minimum value of the groove widths at the same
position on the respective score lines, and an error range average
value (between grooves) indicates the average value of the error
ranges (between grooves) of all the measurement positions.
[0037] Referring to the measurement data shown in FIGS. 5A and 5B,
the accuracy of groove width of the score lines of the example is
much higher than that of groove width of the score lines of the
comparative example.
[0038] FIG. 6 is a table showing the measurements of the actual
measurement values of the groove widths (groove widths W1 in FIG.
2) of the score lines and the evaluations of the machinabilities
and test shot results obtained when the edge angle (angle .theta.2
in FIG. 3B) of the first formed groove, the notch angle .theta.1
(see FIG. 2), and the distance D (see FIG. 2) changed. Ten golf
club heads (Nos. 1 to 10) were measured and evaluated. For golf
club head No. 1, only first formed grooves were machined without
notches.
[0039] In FIG. 6, "in first formation" indicates the groove width
(W2 in FIG. 3B) of the first formed groove, the design value of the
edge angle (angle .theta.2 in FIG. 3B), and the evaluation of the
machinability. "After notch formation" indicates the actual
measurement value of the groove width (W1 in FIG. 2), the design
value of the notch angle .theta.1 (see FIG. 2), the design value of
the distance D (see FIG. 2), and the evaluation of the
machinability. "Test shot result" indicates the test shot result
obtained by using each golf club head.
[0040] As in golf club head Nos. 2 to 10, when the edge angle
.theta.2 of the first formed groove, the notch angle .theta.1, and
the distance D change, score lines having a plurality of types of
groove widths can be obtained. When the notches are formed in the
edges of the score lines, not only the machining accuracy of the
score lines can improve but also the degree of freedom of groove
width design can increase.
[0041] As for the machinability of the first formed groove, since
golf cub head No. 1 has the large angle .theta.2, its machinability
was not very good because of the draft. Golf club head Nos. 2 to 10
had no particular problem. Accordingly, from the viewpoint of the
machinability of the first formed groove, the angle .theta.2 is
desirably smaller than 85.degree. and, particularly, is equal to or
smaller than 80.degree.. Upon machining the notch, when the edge
angle .theta.2 of the first formed groove is small, the shake of
the cutting tool and cutting resistance are small. This is
desirable, however, if the edge angle .theta.2 is too small, the
sectional area of the groove becomes small. This undesirably causes
a low spin tendency (tendency for back spin to decrease) in case of
a shot from rough or the like. Therefore, the edge angle .theta.2
of the first formed groove is desirably 60.degree. to
80.degree..
[0042] As for the machinability of the notch, golf club head No. 10
had a large cut amount (distance D: 0.12 mm) so that it was
difficult to attain a satisfactory accuracy. Therefore, from the
viewpoint of the machinability, the distance D is desirably 0.1 mm
or less.
[0043] As for the test shot result, the large notch angle al is
desirable from the viewpoint of an increase in spin amount of a
ball, however, the ball is easily damaged. Also, for a golf club
head for official competitions, the edge angle of a score line is
determined to be 90.degree. or less. Accordingly, golf club head
No. 7 cannot be used for official competitions. When the present
invention is applied to a golf club head for competitions, the
angle .theta.1 is desirably set to 90.degree. or less.
[0044] Golf club head No. 3 (angle .theta.1: 45.degree.) had a low
spin amount of the ball. Accordingly, from the viewpoint of a spin
amount of a ball, the notch angle .theta.1 is preferably 50.degree.
or more. Golf club head Nos. 8 to 10 (angle .theta.1: 90.degree.)
had high spin amounts of the balls but they slightly damaged the
balls. Golf club head No. 6 did not damage the ball much.
[0045] Accordingly, when the spin amount of a ball is considered to
be important while being applied in official competitions, the
notch angle .theta.1 is desirably 50.degree. to 90.degree. (both
inclusive). In addition, when the machinability of the first formed
groove is considered, the notch angle 61 is desirably between the
angle .theta.2 and 90.degree. (both inclusive). In this case, the
machinability of the first formed groove can be improved by
decreasing the angle .theta.2 while preventing a decrease in spin
amount by forming the notches.
[0046] When damage to the ball is prevented while considering the
spin amount of a ball to be important, the notch angle 61 is
desirably 50.degree. (inclusive) to 90.degree. (exclusive) and
particularly 50.degree. to 85.degree. (both inclusive). In
addition, when the machinability of the first formed groove is
considered, the notch angle .theta.1 is desirably between the angle
.theta.2 and 85.degree. (both inclusive).
[0047] 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.
* * * * *