U.S. patent application number 12/987429 was filed with the patent office on 2011-05-05 for bat for baseball or softball.
This patent application is currently assigned to NHK SHAFT CO., LTD.. Invention is credited to Shuichi NAGASHIMA, Katsumi SHIMOHIRA, Makoto WATARI.
Application Number | 20110105255 12/987429 |
Document ID | / |
Family ID | 41267330 |
Filed Date | 2011-05-05 |
United States Patent
Application |
20110105255 |
Kind Code |
A1 |
WATARI; Makoto ; et
al. |
May 5, 2011 |
BAT FOR BASEBALL OR SOFTBALL
Abstract
A bat for baseball or softball of the present invention includes
a first tube having an impact part, a step part and a stopper part,
a cylindrical second tube, a fixing component being inserted
between the first tube and second tube, the step part having an
exterior diameter larger than that of the impact part and smaller
than an interior diameter of the second tube, the stopper part
having an exterior diameter larger than that of the step part and
large than the interior diameter of the second tube, the second
tube is held of an exterior periphery of the impact part, one end
of the second tube is fixed between the stopper part and the step
part by an adhesive and the other end is fixed by an adhesive on
the fixing component, and a crevice is formed between the first
tube and the second tube.
Inventors: |
WATARI; Makoto;
(Yokohama-shi, JP) ; SHIMOHIRA; Katsumi;
(Yokohama-shi, JP) ; NAGASHIMA; Shuichi;
(Yokohama-sh, JP) |
Assignee: |
NHK SHAFT CO., LTD.
Yokohama-shi
JP
|
Family ID: |
41267330 |
Appl. No.: |
12/987429 |
Filed: |
January 10, 2011 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
12165718 |
Jul 1, 2008 |
|
|
|
12987429 |
|
|
|
|
Current U.S.
Class: |
473/566 ;
473/564 |
Current CPC
Class: |
A63B 59/50 20151001;
A63B 2102/18 20151001; A63B 2209/023 20130101 |
Class at
Publication: |
473/566 ;
473/564 |
International
Class: |
A63B 59/06 20060101
A63B059/06 |
Foreign Application Data
Date |
Code |
Application Number |
May 9, 2008 |
JP |
P2008-123266 |
Claims
1. A bat for baseball or softball comprising: a first tube having a
grip part, a taper part, an impact part and a tip part, a step part
having a larger exterior diameter than an exterior diameter of said
impact part, a first stopper part having a larger exterior diameter
than an exterior diameter of said step part and said first tube
also including a second stopper part having a larger exterior
diameter than said exterior diameter of said first stopper part; a
cylindrical second tube having two ends which are open, and having
an interior diameter which is larger an exterior diameter of said
step part of said first tube and smaller than said exterior
diameter of said first stopper part of said first tube; a
cylindrical third tube having two ends which are open, and also
having an interior diameter which is larger than an exterior
diameter of said second tube and smaller than said exterior
diameter of said second stopper part of said first tube; a fixing
component including a body part, an insertion part and a fixing
component stopper part, said insertion part being inserted between
said first tube and said second tube, and said fixing component
stopper part which forms a crevice between said second tube and
said third tube, said fixing component latching said second tube
and said third tube to an exterior periphery of said first tube; a
first crevice located between said second tube and said first tube,
said first crevice being formed by said second tube being attached
to an exterior periphery of said impact part of said first tube,
one end of said second tube being fixed between said step part of
said first tube and said first stopper part by an adhesive, and the
other end of said second tube being fixed by said adhesive with
said insertion part of said fixing component, said fixing component
being inserted between said second tube and said first tube; and a
second crevice located between said third tube and said second
tube, said second crevice being formed by said third tube being
attached to an exterior periphery of said second tube, one end of
said third tube being fixed between said first stopper part of said
first tube and said second stopper part by said adhesive and the
other end of said third tube being fixed by said adhesive with said
fixing component stopper part of said fixing component.
2. The bat for baseball or softball according to claim 1, further
comprising a cap, said cap having a cap tip part, a recessed part
and a fixing part, a tip of said tip part of said first tube having
a curled part which curves inwards, and an exterior diameter of
said fixing part of said cap being smaller than an interior
diameter of said first tube from said curled part to said second
stopper part, and an exterior diameter of said recessed part of
said cap being smaller than an interior diameter of said curled
part of said first tube and said recessed part being latched by
said curled part.
3. The bat for baseball or softball according to claim 1, wherein a
tip of said tip part curves inwards and is closed.
4. The bat for baseball or softball according to claim 1, further
comprising a spacer, said spacer being inserted between said first
tube and said second tube and also between said second tube and
said third tube, said first tube includes a first stopper part
having an exterior diameter which is larger than an interior
diameter of said second tube and which is smaller than an interior
diameter of said third tube, and also includes a second stopper
part having an exterior diameter which is larger than said exterior
diameter of said first stopper part and which is larger than said
interior diameter of said third tube, said second tube is attached
to an exterior periphery of said impact part of said first tube,
and one end of said second tube is fixed to a tip of a first
stopper part side of said impact part of said first tube by said
adhesive and said spacer, and the other end of said second tube
being fixed by said adhesive with said insertion part of said
fixing component, and said first crevice being formed between said
second tube and said first second tube, and said third tube is
attached to an exterior periphery of said second tube, and one end
of said third tube is fixed between said first stopper part and
said second stopper part by said adhesive and said spacer, and the
other end of said third tube being fixed by said adhesive with said
fixing component first stopper part of said fixing component, and
said second crevice being formed between said third tube and said
second tube.
5. The bat for baseball or softball according to claim 2, wherein
said first tube includes a groove in a place of a taper part side
of said impact part, said fixing component further having a
protrusion part on a side in which said insertion part faces said
first tube, said fixing component being inserted between said first
tube and said second tube, and also between said second tube and
said third tube, and said protrusion part being fitted with said
groove of said first tube.
6. The bat for baseball or softball according to claim 5, wherein
said first tube is formed from an aluminum alloy or an alloy steel
and one of either said second tube or said third tube is formed
from titanium, a titanium alloy, a magnesium alloy or an alloy
steel.
7. A bat for baseball or softball comprising: a first tube having a
grip part, a taper part, an impact part, a tip part, a step part
having a larger exterior diameter than an exterior diameter of said
impact part and said first tube also including a stopper part
having a larger exterior diameter than said exterior diameter of
said step part; a plurality of cylindrical second tubes each having
two ends respectively, said ends being open, and each of the
plurality of second tubes having an interior diameter and an
exterior diameter which are the same respectively, said interior
diameter of each of the plurality of second tubes being larger than
said exterior diameter of said step part of said first tube and
smaller than said exterior diameter of said stopper part of said
first tube, and at least one of said plurality of second tubes
being formed from a material which is different to the other tubes;
a first fixing component including a body part and an insertion
part, said insertion part being inserted between said first tube
and said second tube, said first fixing component latching said
second tube to an exterior periphery of said first tube; a second
fixing component latching said plurality of second tubes to said
exterior periphery of said first tube; and a crevice located
between said first tube and said plurality of second tubes, said
crevice being formed by each of said plurality of second tubes
being attached to the exterior periphery of said impact part of
said first tube, an end of one of said plurality of second tubes
being fixed between said step part of said first tube and said
stopper part by an adhesive, the other end of one of said plurality
of second tubes being fixed by said adhesive with said second
fixing component, an end of another one of said plurality of second
tubes being fixed by said adhesive with said second fixing
component, the other end of another one of said plurality of second
tubes being fixed by said adhesive with said first fixing
component, and both ends of yet another one or more second tubes of
said plurality of second tubes being fixed by said adhesive with
said second fixing component.
8. The bat for baseball or softball according to claim 7, further
comprising a cap, said cap having a cap tip part, a recessed part
and a fixing part, a tip of said tip part of said first tube having
a curled part which curves inwards, and an exterior diameter of
said fixing part of said cap being smaller than an interior
diameter of said first tube from said curled part to said stopper
part, and an exterior diameter of said recessed part of said cap
being smaller than an interior diameter of said curled part of said
first tube and said recessed part being latched by said curled
part.
9. The bat for baseball or softball according to claim 7, wherein a
tip of said tip part curves inwards and is closed.
10. The bat for baseball or softball according to claim 7, further
comprising a spacer, said spacer being inserted between said first
tube and one of said plurality of said second tubes, said first
tube includes only a stopper part having a larger exterior diameter
than an exterior diameter of said impact part and a larger exterior
diameter than an interior diameter of each of said plurality of
second tubes, and each of said plurality of second tubes is
attached to an exterior periphery of said impact part of said first
tube respectively, wherein a crevice being formed between said
first tube and said plurality of second tubes, by an end of one of
said plurality of second tubes being fixed between said step part
of said first tube and said stopper part by an adhesive and a
spacer, the other end of one of said plurality of second tubes
being fixed by said adhesive with said second fixing component, and
an end of another one of said plurality of second tubes being fixed
by said adhesive with said second fixing component, the other end
of another one of said plurality of second tubes being fixed by
said adhesive with said first fixing component, and both ends of
yet another one or more second tubes of said plurality of second
tubes being fixed by said adhesive with said second fixing
component.
11. The bat for baseball or softball according to claim 8, wherein
said first tube includes a groove in a place of a taper part side
of said impact part, said fixing component further having a
protrusion part on a side in which said insertion part faces said
first tube, said fixing component being inserted between said first
tube and one of said plurality of second tubes, and said protrusion
part being fitted with said groove of said first tube.
12. The bat for baseball or softball according to claim 11, wherein
said first tube is formed from an aluminum alloy or an alloy steel
and at least one of said plurality of second tubes is formed from
titanium, a titanium alloy, a magnesium alloy or an alloy steel.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based upon and claims the benefit of
priority from the prior Japanese Patent Application No.
2008-123266, filed on May, 9, 2008, the entire contents of which
are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to improving the rebound
characteristics of a bat for baseball or softball.
[0004] 2. Description of the Related Art
[0005] Conventionally, the flying distance of a ball is thought to
be extended when hit by a high strength bat. This is because it was
considered that a bat with a high degree of strength has excellent
rebound characteristics and the flying distance of a ball depended
solely on these rebound characteristics of the bat. However, in
recent years, it is understood that a bat which can reduce the
consumption of impact energy as ball transformation energy when a
ball and bat collide, can extend the flying distance of a ball. In
addition, it is understood that the higher the rebound force/power
of the bat itself, the further the flying distance of a ball is
extended. Thus, as shown in Japanese Laid Open Patent 2001-79131, a
double layered bat formed by arranging a further thin metal tube
(called "exterior tube" and "interior tube" respectively) on the
exterior or the interior of the body of a metal bat is proposed.
That is, a crevice is arranged between the bat body and the
exterior tube or the bat body and the interior tube. In this way,
an attempt is made to extend the flying distance of a ball by
reducing the consumption of impact energy as ball transformation
energy by bending of a bat's thin tube when a ball is hit.
[0006] FIG. 11 is a longitudinal direction notch sectional view and
a cross sectional view of the line A-A' in a width direction of one
example of a double layered bat. The bat in FIG. 11 is comprised
from a bat tip part 1, a bat impact part 2, a bat taper part 3 and
a bat grip part 4. An exterior tube 20 fits onto the bat from the
bat tip part 1 up to the bat taper part 3. In the bat taper part 3,
the exterior tube 20 is latched to a hollow for latching 70 which
is arranged on the bat by a swaging process or spinning process. At
this time, the exterior tube 20 is latched so that a fixed crevice
is arranged between the bat and the exterior tube 20. Here the grip
part 4 is the part of the bat which is held by a batter and is the
thinnest part of the bat which extends to a predetermined length
from the end of the grip. The taper part 3 is the part which has a
diameter which gradually becomes larger from the grip part 4. In
addition, the bat tip part 1 is the part which is formed by a resin
for example, and is the end of the bat located in the furthest
position from the grip end. The bat impact part 2 is the part
except the bat tip part 1, the bat taper part 3 and the bat grip
part 4, and which extends to a predetermined length towards the bat
tip part 1 from the widest part of the taper part 3 part (in the
case of a double layered bat, both an exterior tube and an interior
tube of a double layered structure located at the part which
extends to a predetermined length towards the bat tip part 1 from
the widest part of the taper part 3 part). The bat impact part 2 is
generally the part which is suitable for hitting a ball.
Furthermore, depending on the manufacturing method, the tip part is
sometimes formed as a part of the bat impact part 2 from metal and
in this case, the bat is comprised of the bat impact part 2, the
bat taper part 3 and the bat grip part 4.
[0007] This double layered bat requires latching two tubes during
final processing by a swaging process for example. In this case, in
order to remove processing distortions, a heat treatment is
performed after swaging processing and stress must be released.
However, control of a heat treatment of a part having a double
layered structure is difficult and securing sufficient strength and
durability is also difficult. Particularly, in the case where the
material of the bat body and exterior tube or bat body and interior
tube are different, because the melting point of each material is
also different, control of the temperature and time of a heat
treatment becomes complex.
[0008] However, as another approach, a recess part is arranged in
the metal bat and a layer of urethane is formed on this recess
part, as shown in Japanese Laid Open Patent 2005-305146. In the
present specification, this type of bat is called a hybrid type
double layered bat.
[0009] FIG. 12 is a longitudinal direction notch sectional view and
a cross sectional view of the line B-B' in a width direction of one
example of a hybrid type double layered bat. In FIG. 12, the
diameter of the bat impact part 2 of the bat body 10 is reduced
smoothly by a swaging process for example, from a boundary with the
bat tip part 1 and from a boundary with the bat taper part 3 in the
direction of the interior of the bat impact part 2. Then, a
flexible layer of urethane 101 is formed to cover/enclose the bat
body 10 and a hard layer of urethane 102 is formed on the exterior
surface. In this hybrid type bat, when a ball collides with the
bat, the two layers of urethane (101 and 102) contract and
consumption of the impact energy as ball transformation energy is
reduced as much as possible and the flying distance of the ball can
be extended. However, because an urethane layer deteriorates by
secular distortion, the durability of the bat is inferior compared
to a metal manufactured bat. In addition, the bat also suffered
from an increase in miss hits.
[0010] Thus, as shown in Japanese Laid Open Patent 2008-29620, a
double layered bat was manufactured using a fixing component.
BRIEF SUMMARY OF THE INVENTION
[0011] A bat for baseball or softball related to one embodiment of
the present invention includes; a first tube having a grip part, a
taper part, an impact part, a tip part, a step part having a larger
exterior diameter than an exterior diameter of the impact part and
the first tube also including a stopper part having a larger
exterior diameter than the exterior diameter of the step part; a
cylindrical second tube having two ends which are open, and having
an interior diameter which is larger than the exterior diameter of
the step part of the first tube and smaller than the exterior
diameter of the stopper part of the first tube; a fixing component
including a body part and an insertion part, the insertion part
being inserted between the first tube and the second tube, the
fixing component latching the second tube to an exterior periphery
of the first tube; and a crevice located between the first tube and
the second tube, the crevice being formed by the second tube being
attached to an exterior periphery of the impact part of the first
tube, one end of the second tube being fixed between the step part
of the first tube and the stopper part by an adhesive, and the
other end of the second tube being fixed by the adhesive with the
insertion part of the fixing component, the fixing component being
inserted between the second tube and the first tube.
[0012] A bat for baseball or softball related to one embodiment of
the present invention includes; a first tube having a grip part, a
taper part, an impact part and a tip part, a step part having a
larger exterior diameter than an exterior diameter of the impact
part, a first stopper part having a larger exterior diameter than
an exterior diameter of the step part and the first tube also
including a second stopper part having a larger exterior diameter
than the exterior diameter of the first stopper part; a cylindrical
second tube having two ends which are open, and having an interior
diameter which is larger an exterior diameter of the step part of
the first tube and smaller than the exterior diameter of the first
stopper part of the first tube; a cylindrical third tube having two
ends which are open, and also having an interior diameter which is
larger than an exterior diameter of the second tube and smaller
than the exterior diameter of the second stopper part of the first
tube; a fixing component including a body part, an insertion part
and a fixing component stopper part, the insertion part being
inserted between the first tube and the second tube, and the fixing
component stopper part which forms a crevice between the second
tube and the third tube, the fixing component latching the second
tube and the third tube to an exterior periphery of the first tube;
a first crevice located between the second tube and the first tube,
the first crevice being formed by the second tube being attached to
an exterior periphery of the impact part of the first tube, one end
of the second tube being fixed between the step part of the first
tube and the first stopper part by an adhesive, and the other end
of the second tube being fixed by the adhesive with the insertion
part of the fixing component, the fixing component being inserted
between the second tube and the first tube; and a second crevice
located between the third tube and the second tube, the second
crevice being formed by the third tube being attached to an
exterior periphery of the second tube, one end of the third tube
being fixed between the first stopper part of the first tube and
the second stopper part by the adhesive and the other end of the
third tube being fixed by the adhesive with the fixing component
stopper part of the fixing component.
[0013] A bat for baseball or softball related to one embodiment of
the present invention includes; a first tube having a grip part, a
taper part, an impact part, a tip part, a step part having a larger
exterior diameter than an exterior diameter of the impact part and
the first tube also including a stopper part having a larger
exterior diameter than the exterior diameter of the step part; a
plurality of cylindrical second tubes each having two ends
respectively, the ends being open, and each of the plurality of
second tubes having an interior diameter and an exterior diameter
which are the same respectively, the interior diameter of each of
the plurality of second tubes being larger than the exterior
diameter of the step part of the first tube and smaller than the
exterior diameter of the stopper part of the first tube, and at
least one of the plurality of second tubes being formed from a
material which is different to the other tubes; a first fixing
component including a body part and an insertion part, the
insertion part being inserted between the first tube and the second
tube, the first fixing component latching the second tube to an
exterior periphery of the first tube; a second fixing component
latching the plurality of second tubes to the exterior periphery of
the first tube; and a crevice located between the first tube and
the plurality of second tubes, the crevice being formed by each of
the plurality of second tubes being attached to the exterior
periphery of the impact part of the first tube, an end of one of
the plurality of second tubes being fixed between the step part of
the first tube and the stopper part by an adhesive, the other end
of one of the plurality of second tubes being fixed by the adhesive
with the second fixing component, an end of another one of the
plurality of second tubes being fixed by the adhesive with the
second fixing component, the other end of another one of the
plurality of second tubes being fixed by the adhesive with the
first fixing component, and both ends of yet another one or more
second tubes of the plurality of second tubes being fixed by the
adhesive with the second fixing component.
[0014] In addition, the bat for baseball or softball according to
this invention, may further comprise a cap, the cap having a cap
tip part, a recessed part and a fixing part, a tip of the tip part
of the first tube having a curled part which curves inwards, an
exterior diameter of the fixing part of the cap being smaller than
an interior diameter of the first tube from the curled part to the
stopper part, and an exterior diameter of the recessed part of the
cap being smaller than an interior diameter of the curled part of
the first tube and the recessed part being latched by the curled
part.
[0015] The bat for baseball or softball according to this
invention, wherein a tip of the tip part may curve inwards and may
be closed.
[0016] The bat for baseball or softball according to this
invention, may further comprise a spacer, the spacer being inserted
between the first tube and the second tube, the first tube includes
a stopper part having a larger exterior diameter than an exterior
diameter of the impact part and a larger exterior diameter than an
interior diameter of the second tube, and the second tube is
attached to an exterior periphery of the impact part of the first
tube, and one end of the second tube is fixed to a tip of a tip
part side of the impact part of the first tube by the adhesive and
the spacer, and the other end of the second tube being fixed by the
adhesive with the insertion part of the fixing component, the
fixing component being inserted between the second tube and the
first tube, and the crevice being formed between the first tube and
the second tube.
[0017] The bat for baseball or softball according to this
invention, wherein the first tube may include a groove in a place
of a taper part side of the impact part, the fixing component
further having a protrusion part on a side in which the insertion
part faces a first tube, the fixing component being inserted
between the first tube and the second tube, and the protrusion part
being fitted with the groove of the first tube.
[0018] The bat for baseball or softball according to this
invention, wherein the first tube may be formed from an aluminum
alloy or an alloy steel and the second tube may be formed from
titanium, a titanium alloy, a magnesium alloy or an alloy
steel.
[0019] The bat for baseball or softball according to this
invention, wherein the first tube may further include a second step
part having a larger exterior diameter than an exterior diameter of
the impact part, the exterior diameter of the second step part
being smaller than an interior diameter of the second tube, and
also includes a second stopper part having a larger exterior
diameter than the exterior diameter of the second step part, the
exterior diameter of the second stopper part being larger than the
interior diameter of the second tube, the second tube is attached
to an exterior periphery of the impact part of the first tube, and
wherein one end of the second tube is fixed by the adhesive between
the step part of the first tube and the stopper part of the first
tube, the other end of the second tube is fixed by the adhesive
between the second step part of the first tube and the second
stopper part of the first tube, and the second stopper part is
formed so that the second stopper part has a larger exterior
diameter than an interior diameter of the second tube after the
second tube is fixed between the stopper part and the step part and
also between the second step part and the second stopper part.
[0020] The bat for baseball or softball according to this
invention, wherein the stopper part may be formed in a position at
least 100 mm or more from a tip of the tip part of the first tube,
and the second tube is arranged in the best position for an
impact.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 (a) shows a longitudinal direction notch sectional
view of bat for baseball or softball related to embodiment one of
the present invention.
[0022] FIG. 1 (b) shows a cross sectional view of the line
.alpha.-.alpha.' in a width direction of bat for baseball or
softball related to embodiment one of the present invention.
[0023] FIG. 2 shows an enlarged cross sectional view in a
longitudinal direction of a bat tip part and a bat impact part of a
bat for baseball or softball related to embodiment one of the
present invention.
[0024] FIG. 3 shows an enlarged cross sectional view in a
longitudinal direction of a bat impact part and a taper part of a
bat for baseball or softball related to embodiment one of the
present invention.
[0025] FIG. 4 shows an enlarged cross sectional view in a
longitudinal direction of a bat tip part of a bat for baseball or
softball related to example one of embodiment one of the present
invention.
[0026] FIG. 5 shows an enlarged cross sectional view in a
longitudinal direction of a bat impact part and a taper part of a
bat for baseball or softball related to example two of embodiment
one of the present invention.
[0027] FIG. 6 shows an enlarged cross sectional view in a
longitudinal direction of a bat tip part of a bat for baseball or
softball related to example three of embodiment one of the present
invention.
[0028] FIG. 7 shows an enlarged cross sectional view in a
longitudinal direction of a bat tip part of a bat for baseball or
softball related to example three of embodiment one of the present
invention.
[0029] FIG. 8 (a) shows a longitudinal direction notch sectional
view of a bat for baseball or softball related to embodiment two of
the present invention.
[0030] FIG. 8 (b) shows a cross sectional view of the line
.beta.-.beta.' in a width direction of a bat for baseball or
softball related to embodiment two of the present invention.
[0031] FIG. 9 (a) shows a longitudinal direction surface view of a
bat for baseball or softball related to embodiment three of the
present invention.
[0032] FIG. 9 (b) shows a longitudinal direction notch sectional
view of a bat for baseball or softball related to embodiment three
of the present invention.
[0033] FIG. 10 (a) shows a longitudinal direction surface view of a
bat for baseball or softball related to embodiment four of the
present invention.
[0034] FIG. 10 (b) shows a longitudinal direction notch sectional
view of a bat for baseball or softball related to embodiment four
of the present invention.
[0035] FIG. 11 (a) shows a longitudinal direction notch sectional
view of one example of a double layered bat.
[0036] FIG. 11 (b) shows a cross sectional view of the line A-A' in
a width direction of one example of a double layered bat.
[0037] FIG. 12 (a) shows a longitudinal direction notch sectional
view of one example of a hybrid type double layered bat.
[0038] FIG. 12 (b) shows a cross sectional view of the line B-B' in
a width direction of one example of a hybrid type double layered
bat.
DETAILED DESCRIPTION OF THE INVENTION
Structure of a Double Layered Bat
[0039] The present invention can reduce the consumption of impact
energy as ball transformation energy and in particular a bat for
baseball or softball is proposed in which the strength of the bat
tip part is reinforced. Furthermore, in the present invention, a
bat for baseball or softball is proposed which is inexpensive and
can be easily manufactured.
[0040] The bat for baseball or softball related to embodiment one
of the present invention will be explained below based on the
diagrams. Furthermore, the same structural components have the same
symbols and thus an explanation of these components which overlap
between embodiments will be omitted. FIG. 1 is a longitudinal
direction notch sectional view and a cross sectional view of the
line .alpha.-.alpha.' in a width direction of bat for baseball or
softball related to embodiment one of the present invention. In
addition, FIG. 2 is an enlarged cross sectional view in a
longitudinal direction of a bat tip part and a bat impact part of a
bat for baseball or softball related to embodiment one of the
present invention. Furthermore, one example of a bat for baseball
or softball of the present invention is shown in the embodiments.
However, the bat for baseball or softball of the present invention
is not limited to these embodiments.
[0041] In FIG. 1, the bat for baseball or softball related to
embodiment one of the present invention is roughly comprised of a
first tube 15, a second tube 20, a fixing component 30 and a cap
40. The first tube 15 includes a tip part 11, an impact part 12, a
taper part 13 and a grip part 14 and the second tube 20 is fixed to
the exterior of the impact part 12 of the first tube 15.
Furthermore, in embodiment one of the present invention, the second
tube 20 is sometimes called an exterior tube 20. In addition, in
the bat for baseball or softball related to embodiment one of the
present invention, the impact part which hits a ball is formed as
one part comprising the impact part 12 of the first tube 15 and the
second tube 20, however, for the purposes of explanation, only this
part of the first tube 15 is called the impact part 12 below.
[0042] in FIG. 1, the first tube 15 is the part which forms the
center when a ball is hit by a batter. The batter holds the grip
part 14, swings the bat and hits a ball which is thrown. As stated
above, the first tube 15 is comprised of roughly four component
parts, the tip part 11, the impact part 12, the taper part 13 and
the grip part 14 and is generally formed as one body from an
aluminum alloy or steel alloy in order to secure lightness and
strength. However, the bat is not limited to this. For example, the
bat may also be formed by titanium or a titanium alloy. From the
viewpoint of ease of manufacturing and cost, the material of the
first tube 15 is preferably an A7000 aluminum alloy such as
aluminum alloy AA7050, AA7046 regulated under the American Aluminum
Association Regulation.
[0043] In embodiment one of the present invention, in order to
achieve lightness across an entire bat having a double layered
structure, the first tube 15 is formed with a thickness of 1 mm-3
mm for example. After the first tube 15 is formed from the above
stated metal, a series of heat treatments are performed to remove
any processing distortions and secure a certain level of strength.
By this method, any stress is released and the first tube 15
becomes usable. Furthermore, the above stated thickness is only an
example and not limited to this.
[0044] The first tube 15 is formed by processing a thick
cylindrical tube using a process means such as a swaging process.
In the present embodiment, a tube of aluminum alloy having a
diameter within the range of the largest diameter of a bat
regulated by baseball rules was used. The diameter of this tube is
reduced by processing such as a swaging process from the tip part
11 towards the grip part 14 and the first tube 15 was formed.
First, only a certain diameter of this tube was reduced at a first
place 81 located at a certain distance from the tip part 11 towards
the grip part 14. This certain diameter is equal to the sum of the
thickness of the second tube 20 which is the exterior tube and the
thickness of an adhesive 50. This first place 81 in which the
diameter has been reduced by processing is called a stopper part
18. It is possible to understand the stopper part 18 in detail by
referring to FIG. 2. After the exterior tube 20 is attached and the
double layered bat is formed the stopper part 18 plays the role of
stopping the movement of the exterior tube 20 towards the bat tip
part side.
[0045] Furthermore, the diameter of the tube is gradually reduced
to a certain height (a certain diameter) from a second place 82
located a fixed distance from the stopper part 18 towards the grip
part 14 up to a third place 83. This certain height is the height
of a crevice 60 which is formed between the first tube 15 and the
second tube 20 when the second tube 20 is attached to the first
tube 15 by the adhesive 50. Furthermore, the space between the
second place 82 up to the third place 83 is called a step part 17.
It is possible to understand step part 17 in detail by referring to
FIG. 2. In addition, the space from the stopper part 18 of the
first tube 15 up to the second place 82 is the part in which the
second tube 20 is later fixed by the adhesive 50. In addition, the
space from the stopper part 18 up to the second place 82 is a part
which plays a role equal to the fulcrum of a spring when the second
tube 20 bends at the time of an impact.
[0046] Next, the length equal to that of the impact part 12 is
processed to the same diameter from the third place 83 towards the
grip part 14. Then, the diameter is gradually reduced by a swaging
process towards the grip part 14 from a fourth place 84 which is
located in a place the same length as the impact part 12 from the
third place 83 towards the grip part 14 and the taper part 13 and
grip part 14 are formed. The grip end part is sealed off by
spinning processing. However, processing of the grip end part is
not limited to this. For example, a separate grip end part formed
in advance can be latched by a screw and adhesive or welding. The
method of forming the grip end can be appropriately selected. The
tip of the tip part 11 is curved towards the interior of the bat to
a certain length (below this process is called a curling process)
and the curled part 19 is formed. In other words, the tip of the
tip part 11 is almost bent in a perpendicular direction towards the
interior of the bat. The length which is curved should be a length
sufficient to latch the cap 40 which is processed by press fit
processing, such as 3 mm-10 mm or more preferably 5 mm.
[0047] In addition, the method for forming the first tube 15 is not
limited to that stated above. That is, first, a desired first tube
15 may be formed in the following way. The diameter of one end of
an open cylindrical tube which has an exterior diameter of the
impact part 12 is reduced by a swaging process forming the taper
part 13 and the grip part 14, and the diameter of the other end of
the open cylindrical tube is expanded towards the tip part 11 by a
diameter expanding process so that the stopper part 17 and step
part 18 are formed. The method of forming the first tune 15 can be
appropriately selected. Formation of the grip end by welding or
screwing the grip end which is formed separately in advance or by a
spinning process, and formation of the curled part 19 by a curling
process is the same. Furthermore, the diameter reducing process may
be a method other than the above stated swaging process, for
example, a stepping process or a tapering process.
[0048] The first tube 15 of the bat for baseball or softball
related to embodiment one of the present invention has a step part
17 and a stopper part 18 by the above stated process. The exterior
diameter of the first tube 15 between the step part 17 and the
stopper part 18 is larger than the exterior diameter of the impact
part 12 and smaller than the interior diameter of the second tube
20. However, the exterior diameter of the first tube 15 between the
step part 17 and the stopper part 18 is slightly smaller than the
interior diameter of the second tube 20. Therefore, the second tube
20 is inserted from the grip end side of the first tube 15, one end
of the second tube 20 is fitted onto the exterior of the impact
part 12 of the first tube 15 by the adhesive 50 and the second tube
20 becomes fixed when the adhesive 50 hardens. In addition, the
other end of the second tube 20 is fixed by the fixing component
20, which is explained in detail below, and the adhesive 50. Then,
the second tube 20 is latched to the exterior of the impact part 12
of the first tube 15 and a crevice 60 of a certain height is formed
between the second tube 20 and the first tube 15.
[0049] The exterior diameter of the stopper part 18 is larger than
the interior diameter of the second tube 20 and preferably should
be the same diameter as the exterior diameter of the second tube
20. In this way, when the completed bat is swung, the second tube
20 tries to move towards the tip part 11 by centrifugal force,
however, the movement of the second tube 20 is completely halted by
this stopper part 18. The material of the first tube 15 and the
second tube 20 is different, as will be explained below, however,
because both are formed from a metal alloy, there is no significant
difference in a thermal expansion coefficient. Therefore, the
second tube 20 is completely fixed to the exterior of the impact
part 12 of the first tube 15 and as long as there is no damage to
the tip part 11 of the first tube 15, the second tube 20 will not
jump out from the tip part 11 side or fall out. Furthermore, the
exterior diameter of the stopper part 18 is made the same as the
exterior diameter of the second tube 20 because when the bat is
completed, the exterior surface of the stopper part 18 and the
exterior surface of the second tube 20 are formed as the same
surface.
[0050] The second tube 20 of the bat for baseball or softball
related to embodiment one of the present invention is a cylindrical
tube which has two open ends. The interior diameter of the second
tube 20 is larger than the exterior diameter of the impact part 12
of the first tube 15. More preferably, the interior diameter of the
second tube 20 is about twice as large as the height of the crevice
60 formed between the first tube 15 and the second tube 20 compared
with the exterior diameter of the first tube 15. In addition, the
second tube 20 may be formed from the same aluminum alloy or steel
alloy as the first tube 15 or by a light material having excellent
rebound characteristics such as titanium, a titanium alloy or
magnesium alloy. Furthermore, the second tube 20 may be formed by a
material such as phosphor bronze, a copper alloy, a gold alloy or
platinum alloy. Preferably, the second tube 20 is formed from one
of the following; titanium, titanium alloy, magnesium alloy or
steel alloy. The second tube 20 is formed separately from the first
tube 15 and is used after being separately heat treated. Therefore,
compared to a usual double layered bat, heat treatment is simple
and the particular difficulties involved with heat treating the
first tube 15 and second tube 20 when they are formed from
different material are removed. The second tube 20 with this
material is fixed to the exterior of the impact part 12 of the
first tube 15 so that the crevice 60 having a certain desired
height is formed. In this way, when a ball is hit, ball
transformation energy is absorbed by bending of the impact part
which has a double layered structure and the flight distance of the
ball can be further extended.
[0051] Although not shown in the diagrams, a make-up sheet can be
applied to the exterior of the above stated second tube 20 to the
purpose of protecting the second tube 20 from damage and for design
effect. This make-up sheet can be formed from, for example, a resin
film such as a polyethylene film, an elastomer film and a plastic
film or an FRP (Fiber Reinforced Plastics) sheet.
[0052] The fixing component 30 includes a body part 31 and an
insertion part 32. The insertion part 32 has a certain height. This
height is the height when the crevice 60 having a certain height is
formed between the first tube 15 and the second tube 20 in the case
where the insertion part 32 is inserted between the first tube 15
and the second tube 20 and the two tubes fixed by the adhesive 50.
In other words, this height is set at a height after the height of
the intervening hardened adhesive 50 is subtracted from the certain
height of the formed crevice 60. Furthermore, this insertion part
32 plays a role equivalent to the fulcrum of a spring when the
second tube 20 bends when a ball is hit.
[0053] In the present embodiment a cap 40 is attached to the tip
part 11 of the first tube 15 shown in FIG. 1 by press fit
processing. When the bat is being used, it is usually thrown after
a ball has been hit. In addition, depending on the user, there are
times when the tip of bat hits a spike or is dropped in dirt/mud
and also hits the ground. The cap 40 acts to protect the bat in
these cases. That is, the cap 40 also acts to protect the bat from
damage caused by actions other than hitting a ball.
[0054] The cap 40 which fulfills this function is formed by a resin
in the present embodiment and as stated above, is inserted into the
tip of the first tube 15 by press fit processing. The cap 40 will
be explained in detail while referring to FIG. 2. As is shown in
FIG. 2, the cap 40 is comprised of a cap tip part 41, a cap
recessed part 42, a cap fixing part 43 and a cap second fixing part
44. The cap tip part 41 protects the tip part 11 of the first tube
15 after the bat is formed.
[0055] The cap recessed part 42 plays the role of fixing the cap 40
to the tip part 11 of the first tube 15 in the case where the cap
40 is inserted into the tip part 11 of the first tube 15 by press
fit processing. That is, the exterior diameter of the cap recessed
part 42 is smaller than the interior diameter of the curled part 19
of the tip part 11. Therefore, when press fitted, because the
curled part 19 cuts into the recessed part 42 of the cap 40, the
cap 40 fits onto the tip part 11 of the first tube 15.
[0056] The cap fixing part 43 has a larger exterior diameter than
the interior diameter of the curled part 19. Therefore, when the
cap 40 is once inserted into the tip part 11 of the first tube 15
by press fit processing, this cap fixing part 43 is hooked by the
curled part 19 and the cap 40 is prevented from jumping out.
Furthermore, at the time of press fit processing, the interior of
the tip part 11 of the first tube 15 is applied with the adhesive
50, the adhesive hardens between the exterior of the cap fixing
part 43 and the interior of the tip part 11 of the first tube 15
and the cap 40 is more strongly fixed. In the same way the cap
second fixing part 44 plays the role of fixing the cap 40 to the
tip part 11 of the first tube 15 by the adhesive 50. The cap second
fixing part 44 increases the adhesion when the tip is formed
according to the shape of the interior of the step part 17.
[0057] As stated above, the bat for baseball or softball related to
embodiment one of the present invention is a double layered bat in
which a second tube is attached and fixed to the periphery of an
impact part 12 of a first tube 15. The fixing component 30 latches
one end of this second tube 20 to the first tube 15. FIG. 3 is an
enlarged cross sectional view in a longitudinal direction of a bat
impact part and a taper part of a bat for baseball or softball
related to embodiment one of the present invention.
[0058] As is shown in FIG. 3, the fixing component 30 is formed
from a fixing component body 31 and an insertion part 32. The
fixing component 30 is a part having a donut shape and a circular
hollow space at its center. After the second tube 20 is attached to
the first tube 15, the fixing component 30 is attached to the
exterior periphery of the first tube 15 from the grip end side of
the first tube 15. In addition, the insertion part 32 of the fixing
component 30 is inserted between the first tube 15 and the second
tube 20. At this time, both surfaces of the insertion part 32 of
the fixing component 30 and the interior surface of the body part
31 are applied with the adhesive 50. The fixing component 30 is
fixed to the exterior periphery of the first tube 15 by hardening
of the adhesive 50 and the second tube 20 is fixed to the exterior
periphery of the insertion part 32 of the fixing component 30.
Centrifugal force acts on the exterior tube 20 (second tube) of the
double layered bat which is formed when a ball is hit and so the
exterior tube 20 tries to move towards the bat tip side. Therefore,
locking within the bat tip side of the second tube 20 is extremely
important. On the other hand, a centrifugal force does not act in
the direction of the grip side. Therefore, the latching in these
parts does not require strength when compared to latching in the
tip part. Therefore, it is possible to obtain a sufficient amount
of strength in latching by using the adhesive 50.
[0059] Here, the thickness of the insertion part 32 of the fixing
component 30 is formed at a predetermined thickness. The adhesive
50 which is applied to both surfaces of the insertion part 32
hardens and the first tube 15 and second tube 20 are latched with a
crevice 60 which has a certain height. That is, this predetermined
thickness is a thickness of the thickness to which the height of
the adhesive 50 which hardens on both surfaces was subtracted from
the thickness of the formed crevice 60. In this way, as stated
above, the crevice 60 is formed with a desired height. Furthermore,
the exterior surface of the body part 31 of the fixing component 30
is formed so that its diameter decreases smoothly towards the taper
part 13 of the first tube 15 and so that a protrusion is not formed
on the exterior surface of the bat.
[0060] The above stated fixing component 30 is formed from a
plastic or synthetic rubber such as polyurethane, polyamide or
polyethylene or a different elastomer material, however, the fixing
component material is not limited to this. A synthetic resin, metal
or ceramic may also be used.
[0061] In FIG. 1, the crevice 60 is formed between the first tube
15 and the second tube 20 as stated above. That is, the crevice 60
is formed when one end of the second tube 20 in which both ends are
open is latched to the periphery of a part between the step part 17
and the stopper part 18 of the first tube 15 and the other end is
latched to the periphery of the first tube 15 via the insertion
part 32 of the fixing component 30 which has a predetermined
height. The crevice 60 can be better understood by the cross
sectional diagram in a width direction in FIG. 1 (b). The crevice
60 is located between the second tube 20 and the first tube 15 and
is a space for reducing the consumption of impact energy as ball
transformation energy when the second tube 20 bends inwards when a
ball is hit. Furthermore, the height of this crevice 60 can be
adjusted by a predetermined height (that is, a predetermined
diameter) by reducing the diameter of the step part 17 (Or
expanding the diameter by a processing method). In the present
embodiment the height of the crevice 60 is set between 0.1 mm-3.0
mm, for example, depending on the material etc, of the first tube
15 and the second tube 20.
[Effects of the Double Layered Bat]
[0062] The bat for baseball or softball having the above structure,
related to embodiment one of the present invention is arranged with
the crevice 60 between the first tube 15 (interior tube) and the
second tube 20 (exterior tube). Then, the exterior tube 20 is
formed from a metal having superior rebound characteristics than
the interior tube 15. Therefore, when a ball is hit, mainly the
exterior tube 20 bends inwards, consumption of the impact energy as
ball transformation energy is reduced and because the exterior tube
20 itself has superior rebound characteristics, the flight distance
of the ball can be extended.
[0063] Second, the tip part 11 of the first tube 15 which acts as
the bat's tip is formed from a metal tube, the rigidity of the bat
tip part is high. For example, the rigidity of the bat is higher
than that of the bat cited in document three. Therefore, even if
the ball is hit with the tip end side of this bat, the ball will
fly. Furthermore, as stated above, because the bat is formed from
metal up to the tip part, the third effect is that durability of
the bat is improved.
[0064] As stated above, because the cap 40 is inserted into the tip
part 11 of the first tube 15 by press fit processing, processing
becomes easy. Therefore, the fourth effect is that it is possible
to reduce the operational processes of the bat for baseball or
softball related to embodiment one of this invention. In addition,
there is no need to use complex processes in order to attach the
parts and strict processing accuracy of the tip part 11 of the
first tube 15 is not demanded. Therefore, it is both possible to
reduce the cost of the various parts and therefore the overall
manufacturing costs of the bat.
[0065] Fifth, safety is improved in the bat for baseball or
softball related to embodiment one of this invention. That is, in
this bat as stated above, the exterior tube 20 is latched by the
stopper part 18 of the metal interior tube 15. Because both tubes
are formed from metal, there is no significant difference in a
coefficient of thermal expansion and they can be securely latched
by adjusting the interior and exterior diameters of the two tubes.
Therefore, even if the resin cap 40 is damaged, as long as the
interior tube 15 itself is not damaged, the exterior tube 20 will
not come loose and jump out and thus safety is improved.
[0066] Sixth, the life cycle of the bat for baseball or softball
related to embodiment one of this invention is much longer. The bat
for baseball or softball related to embodiment one of this
invention has a metal, double layered structure, however, the
second tube 20 is attached and fixed via the fixing component 30
with the adhesive 50. Therefore, it is possible to easily replace
the second tube 20 alone which can cause damage when a ball is hit.
In a conventional bat with a metal, double layered structure,
because the exterior tube 20 (or the interior tube 15) is latched
to the body 10 by a swaging process, even when the exterior tube 20
(or the interior tube 15) is damaged, and it could not be replaced.
The life cycle of the bat related to the present embodiment can be
made much longer by replacing the exterior tube 20. Furthermore,
because the second tube of the bat related to the present
embodiment is manufactured from metal, the effects of secular
distortion are few and durability is excellent compared to a hybrid
type double layered bat.
[0067] The consumption of impact energy as ball transformation
energy can be reduced by the present invention and in particular a
bat for baseball or softball is proposed in which the strength of
the bat tip part is reinforced and in addition a bat for baseball
or softball is proposed which is inexpensive and can be easily
manufactured.
Example One
[0068] An example of the bat for baseball or softball related to
embodiment one of the present invention will be explained. As
stated above, the bat for baseball or softball related to
embodiment one of the present invention includes a cap. However, if
the entire bat tip can be formed with the first tube 15, the
durability of the bat tip part is increased. The present example is
an example of forming the bat tip part with the first tube 15.
[0069] FIG. 4 is an enlarged cross sectional view in a longitudinal
direction of a bat tip part of a bat for baseball or softball
related to example one of embodiment one of the present invention.
As is shown in FIG. 4, in the present example, the first tube 15
includes the step part 17 and the stopper part 18 and the crevice
60 is formed between the first tube 15 and the second tube 20. In
this point, this is the same as the bat for baseball or softball
related to embodiment one of the present invention.
[0070] In the bat in example one, the bat is formed with the first
tube 15 up to the tip of the first tube (that is, bat tip) 15 from
the stopper part 18. First, the diameter of one end of the first
tube 15, which has two open ends and a predetermined diameter of
the impact part 12, is reduced by processing. As a result, the part
from the taper part 13 of the first tube 15 to the grip part 14 is
formed. After this, the diameter of the other end of the first tube
15 is expanded by processing. As a result, the step part 17 and the
stopper part 18 are formed. After this, the diameter of the other
end of the first tube 15 is expanded by processing and the step
part 17 and the stopper part 18 are formed. Next, without passing
through the process for forming the curled part 19, the tip part is
closed off by a spinning process. In this way, it is possible to
form the bat of the present example which is formed by metal as far
as the tip part. Because the second tube 20 and the fixing
component 30 are the same as in embodiment one of the present
invention, an explanation here has been omitted. Furthermore, the
first tube 15 which has a predetermined diameter may be formed by
first gradually reducing the diameter of the first tube 15 from the
tip part 11, forming the part from the stopper part 18 to the grip
part 14 and lastly closing the tip part 11.
[0071] Because the bat for baseball or softball related to example
one having this structure is formed up to the tip part 11 with
metal, the rigidity of the tip part 11 is further increased. In
addition, because the bat is formed as one metal part up to the tip
part 11, durability is also further improved. The effects of
increasing the flight distance of a ball by a double layered
structure having a crevice 60, improving safety, increasing the
length of the life cycle of the bat and increasing durability
compared to a hybrid type bat, are the same as the above stated
embodiment one.
Example Two
[0072] Another example of the bat for baseball or softball related
to embodiment one of the present invention will be explained. In
the bat for baseball or softball related to embodiment one of the
present invention, latching of the second tube 20 near the taper
part 13 of the first tube 15 takes place by the fixing component 30
and the adhesive 50. The second example of the bat for baseball or
softball related to embodiment one of the present invention is an
example of further strengthening fixing of this fixing component to
the first tube 15. FIG. 5 is an enlarged cross sectional view in a
longitudinal direction of a bat impact part and a taper part of a
bat for baseball or softball related to example two of embodiment
one of the present invention.
[0073] As is shown in FIG. 5, the fixing component 30 related to
example two includes a protrusion part 33 in addition to a body
part 31 and insertion part 32. Interlocking grooves 16 are formed
by a spinning process on a predetermined place of the first tube
15.
[0074] The fixing method of the exterior tube 20 of the bat for
baseball or softball related to the present example will be
explained. First, interlocking grooves 16 are formed during the
manufacturing process in predetermined places on the first tube 15.
Because the formation method of the taper part 13 etc is the same,
an explanation is omitted here. Next, the exterior tube 20 which
has two ends which are open is attached to the exterior periphery
of the first tube 15 from the grip end side and fixed to the
exterior surface between the step part 17 and the stopper part 18
of the first tube 15 by the adhesive 50. Next, the adhesive 50 is
applied to the interior of the donut shaped fixing component 30 and
then attached to the exterior periphery of the first tube 15 from
the grip end side of the first tube 15. The insertion part 32 is
inserted between the first tube 15 and the second tube 20 and the
protrusion part 33 is interlocked and fixed to the interlocking
grooves 16 which are formed in predetermined places of the first
tube 15 and fixing is strengthened by hardening of the adhesive
50.
[0075] By interlocking and fixing the protrusion part 33 with the
interlocking grooves 16 of the first tube 15, it is possible to
further strengthen fixing of the second tube 20 in the bat for
baseball or softball related to the present example and safety is
also improved. During processing of the first tube 15, the number
of processes which form the interlocking grooves 16 increases,
however, there is no significant extension of the operational
processes. The effects of increasing the flight distance of a ball
by a double layered structure having a crevice 60, improving
safety, increasing the length of the life cycle of the bat,
increasing durability and improving rigidity of the bat tip part
compared to a hybrid type bat, are the same as the above stated
embodiment one and an explanation is omitted here.
[0076] Further, example two can be applied to the bat shown in
example one. In this case the effects are the same as stated
above.
Example Three
[0077] Another example of the bat for baseball or softball related
to embodiment one of the present invention will be explained. As
stated above, in the bat for baseball or softball related to
embodiment one of the present invention, in order to form the
crevice 60 between the first tube 15 and the second tube 20, the
step part 17 is arranged on the first tube 15 by a diameter
reducing process (or a diameter expanding process). However, if
this process is omitted, it is possible to further reduce
operational processes and a reduction in manufacturing costs. The
bat for baseball or softball related to example three does not
include the step part 17 and the crevice 60 is formed by a spacer
52. FIG. 6 and FIG. 7 are enlarged cross sectional views in a
longitudinal direction of the tip part of the bat for baseball or
softball related to example three of embodiment one of the present
invention. FIG. 6 shows a bat with the cap 40 and FIG. 7 shows a
bat without the cap.
[0078] As shown in FIG. 6 in the bat in example three, the impact
part 12 of the first tube 15 extends as far as the tip part 11 and
only the stopper part 18 is formed without forming the step part
17. The formation of the curled part 19 after this is also the
same. Although the step part 17 can be formed without difficulty by
controlling a process machine which smoothly reduces or expands the
diameter of the step part 17, the process requires certain period
of time. Therefore, in order to reduce this process the bat in
example three can be process by significantly reducing the overall
operational time.
[0079] Latching of the exterior tube 20 of the bad related to
example three will be explained. As stated above, the bat of the
present example does not include the step part 17, therefore, the
crevice 60 exists between the impact part 12 of the first tube 15
and the second tube 20. It is difficult to bury the crevice 60
using only the adhesive 50. Thus, the bat in example three, the
first tube 15 and the second tube 20 are fixed by the adhesive 50
via the spacer which has a predetermined height. The height of this
spacer 52 is equal to the height of the crevice 60 which is formed
between the first tube 15 and the second tube 20.
[0080] The spacer 52 is a part which has a hollow center and donut
type cylindrical shape, the exterior periphery of the bottom part
(not shown in the diagram) is large and the exterior diameter of a
side wall part (not shown in the diagram) which extends from the
bottom part, is smaller than the exterior diameter of the bottom
part. More specifically, the exterior diameter of the bottom part
is formed to the same diameter as the exterior diameter of the
first tube 15 between the stopper part 18 and the curled part 19
and the exterior diameter of the side wall part is a diameter in
which the exterior diameter of the bottom part has been reduced
slightly more than the thickness of the second tube 20. That is,
the height of the wall part of the spacer 52 is a little lower than
the certain height of the crevice 60 formed. Therefore, the
thickness of the side wall part of the spacer 52 plays a role
equivalent to a fulcrum of a spring when the second tube 20 bends
when a ball is hit. Furthermore, the material of the spacer 52 is
not limited, however, particularly because it is a part which is
arranged between the side wall surface of the stopper part 18 of
the first tube 15 and the second tube 20, it is preferably formed
from a material having soundproof characteristics so that a metal
sound is not produced when the metal tubes contact.
[0081] Next, the latching method of the second tube 20 which used
the spacer 52 will be explained. The spacer 52 which has the
adhesive 50 applied to its entire surface is attached to the first
tube 15 from the grip end side. The back surface of the bottom part
of the spacer 52 is attached to the stopper part 18 of the first
tube 15 by the adhesive 50. Next, before the adhesive 50, which is
applied to the spacer 52, hardens, the second tube 20 is attached
to the first tube 15 from the grip end side. The height (thickness)
of the side wall part of the spacer 52 is smaller than the height
of the crevice 60 which is formed. Therefore, the second tube 20 is
attached so that it covers the side wall part of the spacer 52. The
second tube 20 is fixed and the crevice 60 is formed between the
impact part 12 of the first tube 15 and the second tube 20 when the
adhesive 50 which is applied, hardens. Furthermore, because the
insertion process of the cap 40 is the same as in the above stated
embodiment one, an explanation is omitted here.
[0082] Because process of processing the step part of the bat for
baseball or softball related to example three having the above
stated structure, is omitted, it is possible to further reduce
operational processes. Therefore, it is also possible to further
reduce manufacturing costs. In addition, the effects of increasing
the flight distance of a ball by a double layered structure having
a crevice 60, improving safety, increasing the length of the life
cycle of the bat, increasing durability and improving rigidity of
the bat tip part compared to a hybrid type bat, are the same as the
above stated embodiment one and an explanation is omitted here.
[0083] Furthermore, example three can also be applied to the bat
shown in example one. This example is shown in FIG. 7. The
manufacturing process and the effects of this example are the same
as those stated above and thus an explanation is omitted here.
Furthermore, it is also possible to use the fixing component 30 of
the bat in example three which is shown in FIG. 6 and FIG. 7 as the
fixing component 30 which has the protrusion part 33 shown in
example two. In this case, the effects and manufacturing method are
the same as in example two and thus an explanation is omitted
here.
Embodiment Two
[0084] The bat for baseball or softball related to embodiment two
of the present invention will be explained. As stated above, the
bat for baseball or softball related to embodiment one of the
present invention is a double layered bat which has a crevice 60.
By forming the bat by fixing two thin metal tubes so that a crevice
is formed, and when the thin metal tubes bend inwards when a ball
is hit it is possible to reduce consumption of impact energy as
ball transformation energy. By increasing the exterior tube 20
forming a three layered structure, it is possible to further reduce
the thickness of each tube respectively. In addition, by a
synergistic effect of the bending of each exterior tube it is
possible to further increase the flight difference of a ball. The
bat for baseball or softball related to embodiment two of the
present invention is a three layered bat. FIG. 8 is a longitudinal
direction notch sectional view and a cross sectional view of the
line .beta.-.beta.' in a width direction of a bat for baseball or
softball related to embodiment two of the present invention.
[0085] As is shown in FIG. 8, the bat for baseball or softball
related to embodiment two of the present invention is comprised of
a first tube 15, a second tube 20, a third tube 25, a fixing
component 30 and a cap 40. The third tube 25 is added to the bat
for baseball or softball related to embodiment one of the present
invention and thus there is no large difference between the
structure which is explained in the preferred embodiment. However,
because the structure of the first tube 15 and the fixing component
30 is changed to correspond with the three layered bat, this point
will be explained in detail. Furthermore, because the same parts as
those of the bat for baseball or softball related to embodiment one
of the present invention have the same symbols, an explanation will
be omitted here.
[0086] In order to latch the two exterior tubes (second tube 20 and
third tube 25) of the three layered bat, the first tube 15 of the
bat for baseball or softball related to embodiment two of the
present invention has a first stopper part 18a, a second stopper
part 18b and a step part 17. Each of these parts is manufactured by
reducing or expanding their respective diameters by a swaging
process etc. in the same way as the bat for baseball or softball
related to embodiment one of the present invention. However, for
example, after forming the second stopper part 18b in a first place
the first stopper part 18a is formed by reducing the certain height
(that is, reducing the certain diameter) in a second place 82 (not
shown in the diagram) in the case where manufacturing is performed
by a diameter reducing process. This certain height is equal to the
height of the crevice 60 which is formed between the third tube 25
and the second tube 20 in addition to the thickness of the second
tube 20.
[0087] Furthermore, the step part 17 is formed by gradually
reducing the certain height (diameter) of the first tube 15 in the
direction of the grip end from a third place 83 which is a certain
length from the first stopper part 18a towards the grip end up to a
fourth place 84. The certain height at this time is the height of
the crevice 60 which is formed between the second tube 20 and the
first tube 15. The impact part 12 is formed by extending the same
diameter of the first tube 15 from the fourth place 84 up to a
fifth place 85 and the taper part 13 and the grip part 14 are
formed by further reducing the diameter of the first tube 15 from
the fifth place 85. The process which formed the curled part 19 on
the tip part 11 is the same as in the bat for baseball or softball
related to embodiment one of the present invention. In addition,
the length of the curled part 19 can be any length as long as it is
sufficient to latch the cap 40 which is later inserted by press fit
processing. The length of the curled part 19 is about 3 mm-10 mm or
more preferably about 5 mm.
[0088] The fixing component 30 includes a body part 31, an
insertion part 32, a first stopper part 34 and a second stopper
part 35. The first stopper part 34 and the second stopper part 35
are formed in a step-like shape from the insertion part 32 which
has a certain thickness (equal to the height of the crevice 60
which is formed between the second tube 20 and the first tube 15
stated above) which is different to the fixing component 30 in
embodiment one of the present invention. The height of the first
stopper part 34 which is formed in a step-like shape is a sum of
the height of the crevice 60 which is formed between the second
tube 20 and the third tube 25 and the thickness of the second tube
25. In addition, the height of the second stopper part 35 is set at
a height roughly equivalent to the thickness of the third tube 25.
In this way, the crevice 60 of a certain height is formed between
the third tube 25 and the second tube 20 and also between the
second tube 20 and the first tube 15. In addition, the exterior
surface of the third tube 25 and the exterior surface of the fixing
component 30 are formed as one surface. Furthermore, the height of
the crevice 60 is appropriately set according to the material used
in the first tube 15, the second tube 20 and the third tube 25. In
embodiment two of the present invention, the height of the crevice
60 is set, for example, between about 0.1 mm-3.0 mm.
[0089] The first tube 15, the second tube 20 and the third tube 25
of the three layered bat of embodiment two are cylindrical metal
tubes which have two open ends respectively. The first tube 15 and
the second tube 20 are generally formed from an aluminum alloy or
steel alloy in order to secure lightness and strength. From the
viewpoint of ease of processing and cost, the material is
preferably an A7000 aluminum alloy such as aluminum alloy AA7050,
AA7046 regulated under the American Aluminum Association
Regulation. In addition the third tube 25 can be formed from an
aluminum alloy or steel alloy the same as the first tube 15 or from
a material such as titanium, a titanium alloy or magnesium alloy
which are light and have excellent rebound characteristics.
Furthermore, the third tube 25 can be formed from a phosphor
bronze, a copper alloy, a gold alloy, or a platinum alloy.
Preferably, the third tube 25 is formed from one of titanium, a
titanium alloy, a magnesium alloy or a steel alloy. Furthermore,
the thickness of the first tube 15, the second tube 20 and the
third tube 25 related to embodiment two is formed thinner than the
thickness of the first tube 15 and the second tube 20 of the bat
for baseball or softball relate to embodiment one of the present
invention. This is because the bat is three layered and in order to
lighten each tube and make the entire bat a predetermined weight.
In addition, because the bat has three layers and because it is
possible to secure a certain strength by the three tubes, it is
possible to lighten the bat by making each one of the tubes
thinner.
[0090] By making the bat for baseball or softball related to
embodiment two a three layered structure it is possible to further
reduce the thickness of each exterior tube and it is also possible
to further improve the flight distance of a ball by a synergistic
effect of the bending of each of the tubes. In addition, the
effects of improving safety, increasing the length of the life
cycle of the bat compared to a hybrid type bat, improving rigidity
of the bat tip part and increasing durability, are the same as the
above stated embodiment one. Furthermore, because two stopper parts
18 are formed in the processing of the first tube 15, the number of
processes increases, however, because it is a process which is
machine controlled, there are hardly any effects. The three layered
bat related to embodiment two can reduce operational processes
compared to a conventional hybrid bat and the bat cited in Patent
Document three.
[0091] Furthermore, the bat for baseball or softball related to
embodiment two can also be transformed into example one, example
two and example three of the bat for baseball or softball related
to embodiment one stated above. That is, the tip part 11 is formed
by the first tube 15 and the cap 40 is omitted, the protrusion part
33 is arranged on the fixing component 30, the latching of the
second tube 20 and the third tube 25 is further strengthened and it
is possible to omit forming the step part 17 of the first tube 15
by using the spacer 52. In addition, the effects of each are the
same as the transformation example of the bat for baseball or
softball related to embodiment one.
Embodiment Three
[0092] The bat for baseball or softball related to embodiment three
of the present invention will be explained. As stated above, the
bat for baseball or softball related to embodiment one of the
present invention is a double layered bat arranged with a crevice
60 between an exterior tube 20 (second tube) and a first tube 15.
By this structure it is possible to reduce consumption of impact
energy as ball transformation energy when the thin metal tubes bend
inwards when a ball is hit. And, by using a material which has
excellent rebound characteristics as the material of the exterior
tube 20 (second tube), for example, titanium or a titanium alloy,
the bat is further constructed to improve the flight distance of a
ball. However, this titanium or titanium alloy is expensive and if
the entire second tube 20 is formed form titanium or a titanium
alloy, manufacturing costs increase significantly. Therefore, if
the exterior tube 20 (second tube) is formed from a plurality of
tubes and titanium or a titanium alloy is used only on a sweet spot
which is the center of an impact with a ball, then an increase in
costs can be controlled. The bat for baseball or softball related
to embodiment three is a bat which has a double layered structure
having an exterior tube 20 which is comprised of a plurality of
tubes. FIG. 9 is a longitudinal direction surface view and a
longitudinal direction notch sectional view of a bat for baseball
or softball related to embodiment three of the present
invention.
[0093] As is shown in FIG. 9, the bat for baseball or softball
related to embodiment three is comprised of a first tube 15, a
second tube 20 which is comprised of three tubes (second tube A20a,
second tube B20b and second tube C20c), a fixing component 30 and a
cap 40. In addition, in order to latch the three tubes of the
second tube 20 while forming the crevice 60, a second fixing
component 36 is used. Because the first tube 15, the fixing
component 30 and the cap 40 are the same as in the bat for baseball
or softball related to embodiment one of the present invention
stated above, the same parts have the same symbols and an
explanation is omitted here.
[0094] The second tube 20 of the bat for baseball or softball
related to embodiment three is comprised of three tubes, second
tube A20a, second tube B20b and second C20c as shown in FIG. 9.
However, FIG. 9 is only an example and the number of second tubes
is not limited to three. In embodiment three, the second tube A20a
and the second tube C20c are formed from the same material as the
first tube 15, namely an aluminum alloy or a steel alloy. From the
viewpoint of ease of processing and cost, the material of the first
tube 15 is preferably an A7000 aluminum alloy such as aluminum
alloy AA7050, AA7046 regulated under the American Aluminum
Association Regulation. The second tube B20b is the part which is
equivalent to what is called the sweet-spot where the ball travels
furthest when hit, and is formed from high cost titanium or a
titanium alloy which has excellent rebound characteristics. The
second tube B20b may be formed from a magnesium alloy, phosphor
bronze, a copper alloy, a gold alloy, or a platinum alloy etc. The
plurality of second tubes are cylindrical and each tube formed with
two ends which are open. The second tubes are each heat treated
separately and used once stress is released. Furthermore, either
the second tube A20a or the second tube C20c may be formed from the
same material as the second tube B20b. As a result, at least one of
the three second tubes (20a, 20b, 20c) is formed from a different
material to the other two tubes. In addition, the three second
tubes (20a, 20b, 20c) are formed to the same thickness.
[0095] The second fixing component 36 is a convex fixing component
in a cross section longitudinal direction and is formed from a
resin the same as the fixing component 30. More specifically, the
second fixing component 36 is formed from a plastic or synthetic
rubber such as polyurethane, polyamide or polyethylene or a
different elastomer material, however, the material of the second
fixing component 36 is not limited to this. A synthetic resin,
metal or ceramic may also be used. The second fixing component 36
is preferably formed from a material having soundproof
characteristics so that a metal sound is not produced when the
first tube 15 and the three second tubes 20 contact when a ball is
hit.
[0096] Here, the bottom part (not shown in the diagram) of the
second fixing component 36 has a certain thickness and this
thickness is equivalent to the height of the crevice 60 which is
formed between the first tube 15 and the plurality of the second
tubes 20. Furthermore, the bottom part of the second fixing
component 36 plays a role equivalent to a fulcrum of a spring when
the second tube 20 bends when a ball is hit. In addition, the
convex shaped protrusion part (not shown in the diagram) of the
second fixing component 36 also has a certain height which is
equivalent to the thickness of each of the three second tubes 20
(20a, 20b, 20c). Therefore, the crevice 60 with a certain height is
formed between the first tube 15 and the plurality of second tubes
20 in the case where the three second tubes 20 (20a, 20b, 20c) are
fixed to the exterior periphery of the impact part 12 of the first
tube 15 via the second fixing component 36 and the adhesive 50. In
addition, the exterior surface of the three second tubes 20 (20a,
20b, 20c), the tip part 11 and the taper part 13 of the first tube
15 and the upper surface of the convex shaped protrusion of the
second fixing component 36 are formed as the same surface.
[0097] Next, the attachment method of the three second tubes 20
(20a, 20b, 20c) will be explained. A first tube 15 is formed in the
same way as the bat for baseball or softball related to embodiment
one of the present invention stated above. Next, using two fixing
components 36, the three second tubes 20 (20a, 20b, 20c) are fixed
via the second fixing components 36 and the adhesive 50. In this
way, the three second tubes 20 (20a, 20b, 20c) become one second
tube 20. This process can be performed before the processing of the
first tube 15 and can also be performed in parallel to the
processing of the first tube 15 by a different production line.
Next, the second tube 20 which has become one tube is attached to
the exterior periphery of the impact part 12 of the first tube 15
from the grip end side of the first tube 15. At this time, the
adhesive 50 is applied to the exterior surface from the step part
17 of the first tube 15 to the stopper part 18 and also applied to
the bottom surface of the second fixing component 36. Next, the
adhesive 50 is applied to the bottom surface of the body part 31 of
the fixing component 30 and the entire surface of the insertion
part 32 and the fixing component 30 is inserted between the first
tube 15 and the second tube 20 from the grip end side of the first
tube 15. When the adhesive 50 hardens, the second tube 20 is fixed
to the impact part 12 of the first tube 15 and a double layered bat
having three second tubes 20 (20a, 20b, 20c) is formed. Because the
process of press fitting the cap 40 is the same as embodiment one
stated above and explanation is omitted here.
[0098] In the bat for baseball or softball related to embodiment
three of the present invention which has the structure explained
above, by arranging the second tube 20b which is formed from
titanium or a titanium alloy having excellent rebound
characteristics only in a sweet-spot position which when hit can
increase the flight distance of a ball, it is possible to reduce
and increase in manufacturing costs even if expensive titanium or a
titanium alloy is used. In addition, it is possible to form the
other second tubes (20a, 20c) with a cheaper metal such as a steel
alloy and thus it is possible to propose a two layered bat in which
a reduction in manufacturing costs can easily be overlapped.
[0099] Furthermore, the second tube 20b which has excellent rebound
characteristics is arranged only on the sweet-spot part and the
other second tubes (20a, 20c) for example, can be formed with a
metal which has poorer rebound characteristics than an aluminum
alloy or a steel alloy. In this case, the bat becomes a bat in
which a ball does not travel as far if hit in a place other than
this sweet-spot, however, this bat can be preferably used as a
practice bat for batting skill acquisition.
[0100] In addition, the effects of increasing the flight distance
of a ball by a double layered structure, reducing operational
processes, improving safety, increasing the length of the life
cycle of the bat compared to a hybrid type bat, increasing
durability and improving rigidity of the bat tip part, are the same
as in the above stated embodiment one and embodiment two of the
present invention and an explanation is omitted here. Furthermore,
a transformed example is possible as in embodiment one and
embodiment two of the present invention stated above wherein the
cap 40 can be omitted by forming the tip part 11 with the first
tube 15, latching of the second tube 20 can be strengthened by
arranging a convex shaped protrusion on the fixing component 30 and
formation of the step part 17 of the first tube 15 can be omitted
by using the spacer 52. In addition, each of these effects is the
same as in the transformed examples of the bat for baseball or
softball related to embodiment one stated above.
Embodiment Four
[0101] Next, the bat for baseball or softball related to embodiment
four of the present invention will be explained. As stated above,
the second tube 20 in the double layered bat related to embodiment
three of the present invention is comprised of a plurality of tubes
and the second tube 20b which is formed from titanium or a titanium
alloy having excellent rebound characteristics, is arranged in the
sweet-spot position. In the bat for baseball or softball related to
embodiment four of the present invention, the arrangement of the
second tube 20 which is formed from titanium or a titanium alloy
having excellent rebound characteristics in the sweet-spot position
is the same as in embodiment three, however, in embodiment four
this second tube 20 is comprised from one tube. FIG. 10 is a
longitudinal direction surface view and a longitudinal direction
notch sectional view of a bat for baseball or softball related to
embodiment four of the present invention.
[0102] As is shown in FIG. 10, the bat for baseball or softball
related to embodiment four of the present invention is comprised of
a first tube 15, a second tube 20 and a cap 40. That is, unlike the
bat for baseball or softball related to embodiment one, two and
three of the present invention, there is no need for a fixing
component 30. The second tube 20 is latched by two stopper parts
(18a, 18b) which are arranged on the first tube 15.
[0103] In the bat for baseball or softball related to embodiment
four of the present invention, the second tube 20 is short, about
half the length of the impact part 12 of the first tube 15. Two
step parts 17 and two stopper parts 18 (first step part 17a and
second step part 17b, first stopper part 18a and second stopper
part 18b) of the first tube 15 are formed and the distance from the
bat tip to the first stopper part 18a is extended. In this way, the
length of the second tube 20 which is attached and fixed between
the first stopper part 18a and second stopper part 18b of the first
tube 15 can be reduced. Furthermore, the cap 40 does not include a
cap second fixing component 44. Because the other parts are the
same as in the bat related to embodiment one stated above, the same
parts have the same symbols and an explanation is omitted here.
[0104] Next, the formation method of the first tube 15 of the bat
related to embodiment four will be explained. The material and
thickness of the first tube 15 and the second tube 20 are the same
as in embodiment one stated above therefore an explanation is
omitted here. The first tube 15 is formed by a combination of
diameter reducing and diameter expanding by a swaging process for
example and this is different to the formation of the first tube 15
of the bat related to embodiments one, two and three of the present
invention stated above.
[0105] First, a cylindrical tube (first tube 15) having two ends
which are open and which has a diameter within the range regulated
by baseball regulations is prepared. Next, the diameter of the tube
is reduced by a certain height (diameter) at a first place of a
certain distance from one end of the tube. This first place is the
first stopper 18a. The sweet-spot position of the double layered
bat which is formed is set as a base and this distance is decided
taking the material etc of the first tube 15 and second tube 20
into consideration. In addition, the certain height is equivalent
to the thickness of the second tube 20.
[0106] Next, a diameter of the tube is smoothly reduced a certain
height (diameter) by processing from a second place (not shown in
the diagram) a certain distance from the first stopper 18a towards
the grip end up to a third place (not shown in the diagram). The
first step part 17a is the part between this second place and third
place and the certain height is equivalent to the height of a
crevice 60 which is formed between the first tube 15 and the second
tube 20.
[0107] Furthermore, the diameter of the first tube 15 is processed
at the same diameter from the third place a certain distance up to
a fourth place (not shown in the diagram) towards the grip end.
Next, the diameter of the first tube 15 is smoothly expanded a
certain height (diameter) from the fourth place up to a fifth place
(not shown in the diagram). The part from the fourth place to the
fifth place is the second step part 17b. Furthermore, this height
is equivalent to the height of a crevice 60 which is formed between
the first tube 15 and the second tube 20.
[0108] Next, an adhesive 50 is applied to the exterior surface of
this tube between the first stopper part 18a and the first step
part 17a. And the adhesive 50 is applied to the exterior surface of
the tub from the second step part 17b a certain distance up to a
sixth place towards the grip end. Then, before the adhesive 50
hardens, this tube is inserted from the other end of the tube
towards the first stopper part 18a within the second tube 20 which
is formed in advance to a length corresponding to the distance of
the sweet-spot.
[0109] Here, the exterior diameter of the second tube is the same
as the exterior diameter of the part between one end of the above
stated tube (first tube 15) and the first place. In addition, the
interior diameter of the second tube is a slightly larger than the
exterior diameter between the first stopper part 18a and the second
place which are formed on the above stated tube (first tube 15),
and slightly larger than the exterior diameter between the fifth
place and the sixth place. Therefore, the second tube 20 covers the
exterior surface of the first tube 15 from the first stopper part
18a up to the sixth place and the exterior surface of the tip part
11 of the first tube 15 and the exterior surface of the second tube
20 are formed into one surface.
[0110] After the adhesive 50 hardens and the second tube 20 is
fixed to the exterior periphery of the impact part 12 of the first
tube 15, the diameter of the first tube 15 is further expanded a
certain height (diameter) in the sixth place. The sixth place is
the second stopper part 18b and the position of the sixth place is
the position of an end part (other end part) which is located on
the opposite side of an end part of the first stopper part 18a side
of the second tube 20 which is attached. In addition, the certain
height is a height equivalent to the thickness of the second tube
20. In this way, the other end of the second tube 20 is latched by
the adhesive 50 between the second step part 17b and the second
stopper part 18b. In addition, the second tube 20 is prevented from
moving back and forth by the first stopper part 18a and the second
stopper part 18b. Then, a crevice 60 having a certain height is
formed by the first step part 17a and the second step part 17b
between the impact par 12 of the first tube 15 and the second tube
20.
[0111] Furthermore, after this a taper part 13 and a grip part 14
are formed by a diameter reducing process and when lastly the grip
end is formed by a spinning process, the first tube 15 is formed.
After this, the first tube 15 is heated while the second tube 20 is
still attached, stress in released and the bat having a certain
strength is formed. This heat treatment should be applied to the
first tube 15 and preferably should be performed by controlling the
temperature so that there is no effect on the adhesive 50 which has
hardened. Because heat treatment is not performed simultaneously on
both the first tube 15 and the second tube 20 which have different
materials as in the bat shown in Patent Document one, control of
the heat treatment process is easy. Next, when the cap 40 is
processed by press fitting the bat related to embodiment four is
completed. Furthermore, because the cap 40 can secure a sufficient
length of the cap fixing component 43, there is no need to form the
second fixing component 44.
[0112] The bat related to embodiment four having the above
described structure has a structure in which the second tube 20 is
only attached to the position of the sweet-spot as can be judged
from the notch cross section in FIG. 10 (b). That is, because a
tube which is formed from a metal having excellent rebound
characteristics is used only on the part which makes a ball travel
far when hit, an increase in manufacturing costs can be
reduced.
[0113] In addition, the effects of increasing the flight distance
of a ball by a double layered structure having a crevice 60,
improving rigidity of the bat tip part, improving safety,
increasing the length of the life cycle of the bat compared to a
hybrid type bat and increasing durability are the same as in the
bat in the above stated embodiment one, embodiment two and
embodiment three of the present invention.
[0114] However, Because the first tube 15 of the bat related to
embodiment four is formed by a combination of a diameter reducing
process and a diameter expanding process, the operational processes
increase compared to the bat related to embodiments one, two and
three of the present invention.
[0115] Furthermore, the bat related to the present embodiment can
be transformed as an example the same as in the above stated
example one and example three of the embodiment one of the present
invention. The effects in this case are also the same. In addition,
as explained in embodiment three, the first tube 15 can be formed
from a metal which has poorer rebound characteristics than an
aluminum alloy a steel alloy and can be used as a practice bat for
batting skill acquisition. The effects in this case are also the
same.
* * * * *