Note: Descriptions are shown in the official language in which they were submitted.
CA 02585434 2007-04-25
WO 2006/058230 PCT/US2005/042770
TITLE
HORIZONTAL ROTARY HOOK FOR SEWING MACHINE
TECHNICAL FIELD
The disclosure relates to a horizontal rotary hook for
a sewing machine which includes an inner bobbin case holder
for accommodating a bobbin and an outer rotating hook which
has a beak and accommodates the bobbin case holder, and more
particularly to such a horizontal rotary hook for a sewing
machine in which the beak is a component separated from the
rotating hook.
BACKGROUND
A horizontal rotary hook providing an easy replacement
of a bobbin has conventionally been used in sewing machines.
The horizontal rotary hook comprises an outer rotating hook
formed with a lace and an inner bobbin case holder which
accommodates a bobbin and is held so as to be rotatable relative
to the lace face. The rotating hook is adapted to be rotated
in a predetermined direction by a sewing machine motor or the
like.
The bobbin case holder is made of a synthetic resin so
that a reduction is achieved in the weight and production cost
thereof. Furthermore, the rotating hook has also been made
of a synthetic resin recently. In this case, a beak is provided
on an outer peripheral wall of the rotating hook for seizing
a loop of bobbin thread. However, when the beak is formed
integrally on the rotating hook, the structure of a forming
die used for forming the rotating hook is complicated.
CA 02585434 2007-04-25
WO 2006/058230 PCT/US2005/042770
Furthermore, the beak necessitates a higher strength than the
other part of the rotating hook. In view of these problems,
a beak member provided with a beak has been proposed to be
formed separately from the rotating hook and mounted on the
rotating hook. For example, JP-U-S60-149388 discloses a
horizontal rotary hook in which a beak is made of a metal and
mounted on an inner peripheral surface of an outer peripheral
wall of the hook so as to be laid on the inner peripheral surface .
However, a thickness of a part of the rotating hook on
which the beak member is laid is increased when the beak member
is mounted inside the outer peripheral wall of the rotating
hook. Consequently, the size of the horizontal rotary hook
is increased.
In order that the increase in the size of the overall
horizontal rotary hook may be limited, the beak member is
suggested to be disposed in an opening formed by cutting out
the outer peripheral wall of the horizontal rotary hook and
mounted to the bottom of the rotating hook by screws so as
to joined to the rotating hook. However, when the beak member
is simply mounted to the bottom of the rotating hook made of
the synthetic resin, a sewing thread is entangled in a space
defined between the inner rotating hook and the beak member.
Upon occurrence of such thread entanglement, the beak member
is instantaneously subjected to a large external stress
traveling outward. As a result, the beak member is deformed
or a part of the beak member mounted to the outer rotating
hook is damaged.
2
CA 02585434 2007-04-25
WO 2006/058230 PCT/US2005/042770
SUMMARY
Therefore, an object of the disclosure is to provide a
horizontal rotary hook for a sewing machine, in which a beak
member separate from the outer rotating hook can be mounted
on the rotating hook reliably and rigidly while the thickness
of the outer peripheral wall of the rotating hook is prevented
from being increased.
In one aspect, the disclosure provides a horizontal
rotary hook for a sewing machine, which includes an inner bobbin
case holder accommodating a bobbin therein and an outer
rotating hook accommodating the bobbin case holder and rotated
in a predetermined direction with the bobbin case holder being
accommodated in the rotating hook, the rotating hook having
an outer peripheral wall formed with a bobbin-thread passing
opening through which the bobbin thread passes, the horizontal
rotary hook comprising an enlarged opening defined in the outer
peripheral wall of the rotating hook so as to be continuous
to the bobbin-thread passing opening, a beak member separate
from the rotating hook and mounted on the rotating hook so
as to close the enlarged opening, and a fitting holder provided
on the rotating hook so that a lower part of the beak member
is fitted thereinto, thereby holding the beak member.
According to the above-described aspect of the disclosure,
the beak member is mounted on the rotating hook so as to close
the enlarged opening. Accordingly, since the beak member is
prevented from being laid on the outer peripheral wall of the
rotating hook, the thickness of the outer peripheral wall of
the rotating hook and accordingly, the entire size of the
horizontal rotary hook can be prevented from being increased.
3
CA 02585434 2007-04-25
WO 2006/058230 PCT/US2005/042770
Further, since the beak member is held by the holder while
being fitted therein, the beak member can be mounted on the
rotating hook reliably and firmly. Additionally, only the
beak member needs to be replaced even when the loop seizing
beak has broken. Consequently, the replacement of the beak
member can render the repair cost lower than the replacement
of the entire rotating hook.
In one embodiment of the disclosure, the beak member has
an outer surface, the rotating hook has a bottom, and the
fitting holder is formed so as to protrude outward from the
outer peripheral wall of the rotating hook and has a reinforcing
peripheral wall continuous to the outer peripheral wall of
the rotating hook and supporting the outer surface of the beak
member and a reinforcing bottom continuous to the bottom of
the rotating hook. Consequently, even if thread entanglement
causes the beak member to be subjected to an outgoing force,
the outer surface side of the beak member can be received and
supported by the reinforcing peripheral wall, whereupon the
mounting strength of the beak member against an outward stress
can be improved.
In another embodiment of the disclosure, the beak member
is made of a synthetic resin and as a result, the production
cost can be reduced. When both beak member and outer rotating
hook are made of a synthetic resin, different materials can
be used so that the material for the beak member has a higher
hardness. Consequently, the strength of the beak member can
be improved.
4
CA 02585434 2007-04-25
WO 2006/058230 PCT/US2005/042770
BRIEF DESCRIPTION OF THE DRAWINGS
Other objects, features and advantages of the disclosure
will become clear upon reviewing the following description
of the illustrative aspects with reference to the accompanying
drawings, in which:
FIG. 1A is a perspective view of a sewing machine in
accordance with one illustrative aspect of the invention;
FIG. 1B is an enlarged perspective view of a needle plate
of the sewing machine;
FIG. 2 is a plan view of a horizontal full rotary hook
of the sewing machine;
FIG. 3 is a plan view of a bobbin case holder of the sewing
machine;
FIG. 4 is a plan view of a rotating hook of the sewing
machine;
FIG. 5 is a perspective view of the rotating hook with
a beak member being exploded;
FIG. 6 is a perspective view of the rotating hook as viewed
from another angle;
FIG. 7 is a view similar to FIG. 4, showing the condition
before the beak member is mounted;
FIG. 8 is a view taken along line 8-8 in FIG. 7;
FIG. 9 is a perspective view of the beak member;
FIG. 10 is an enlarged plan view of a beak of the sewing
Machine;
FIG. 11 is a view of the beak as viewed in the direction
of arrow J in FIG. 10; and
FIG. 12 is a perspective view of a horizontal rotating
hook of the illustrative aspect.
5
CA 02585434 2007-04-25
WO 2006/058230 PCT/US2005/042770
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the invention will be described with
reference to the accompanying drawings. In the embodiment,
the invention is applied to a horizontal full rotary hook in
which an outer rotating hook is rotated continuously in one
direction. Referring first to FIGS. 1A and 1B, an overall
construction of the sewing machine will be described. The
sewing machine comprises a body 51 including a sewing bed 52
and a sewing arm 53 formed integrally with the bed so as to
be mounted over the bed as shown in FIG. 1A. The arm 53 has
a distal end having a needle bar 55 provided with a sewing
needle 54. The needle bar 55 is moved vertically by a driving
mechanism (not shown) . On the other hand, a metal needle plate
56 is mounted on an upper surface of the bed 52 so as to be
opposed to the needle bar 55. The needle plate 56 has a needle
hole through which the needle 54 passes and a plurality of
elongate slits 56b for actuation of a feed dog (not shown).
Further, the needle plate 56 has a rectangular
bobbin-accommodating hole 57 located in front of the needle
hole 56a and the elongate slits 56b. The bobbin-accommodating
hole 57 has two slide grooves 57a formed in right and left
portions thereof (only the left slide groove being shown)
respectively. A transparent slide lid 58 (see FIG. 1A) is
adapted to be inserted into the grooves 57a so as to be slidable
front and back, thereby closing and opening the
bobbin-accommodating hole 57.
A cloth feed mechanism (not shown) is provided inside
the bed 52 for driving the feed dog in synchronization with
6
CA 02585434 2007-04-25
WO 2006/058230 PCT/US2005/042770
the vertical movement of the needle bar 55. Further, a
horizontal full rotary hook 1 of the embodiment is located
below the bobbin-accommodating hole 57. The horizontal full
rotary hook 1 includes a beak member 5 and an outer rotating
hook 3 (see FIG. 2) horizontally rotated in synchronization
with the vertical movement of the needle bar 55 and an inner
bobbin case holder 2 (see FIG. 2) . A bobbin 7 on which a bobbin
thread 59 is wound is detachably accommodated in the inner
rotating hook bobbin case holder 2 as shown in FIG. 1B. A
plastic presser plate 60 is mounted on the underside of the
needle plate 56 so as to be located in the bobbin-accommodating
hole 57. The presser plate 60 has an opening through which
the bobbin 7 is put into and taken out of the bobbin case holder
2. The presser plate 60 further has a rotation limiting portion
(not shown) formed on the underside thereof for limiting
rotation of the bobbin case holder 2.
In the sewing machine thus constructed, when the rotating
hook 3 is rotated counterclockwise in synchronization with
the vertical movement of the needle bar 55, a loop of needle
thread (not shown) formed by a sewing needle 54 below an eye
56a of the sewing needle is caught by a loop seizing beak member
5. This direction of rotation will hereinafter be referred
to as "hook rotating direction A." The thread loop is then
entangled with the bobbin thread 59 while being passed outside
the bobbin case holder 2, whereby a stitch is formed.
The horizontal full rotary hook 1 will now be described
in detail with reference to FIGS. 2 to 12. The bobbin case
holder 2 will first be described. Referring to FIGS. 3 and
12, the bobbin case holder 2 is made of a synthetic resin
7
CA 02585434 2007-04-25
WO 2006/058230 PCT/US2005/042770
material such as nylon resin and formed into the shape of a
substantially cylindrical shallow container. An interior of
the bobbin case holder 2 serves as a bobbin-accommodating
section 11 for accommodating the bobbin 7. The bobbin case
holder 2 has a bottom with a centrally formed shaft 8 with
which the bobbin 7 is to be fitted.
Referring to FIG. 3, the bobbin case holder 2 includes
an outer periphery formed with a rotation limiter 12 located
at the front as viewed in FIG. 3 and preventing rotation of
the bobbin case holder 2. The outer periphery of the bobbin
case holder 2 is further formed with a notch 10 located at
an inner side as viewed in FIG. 3 and allowing the needle 54
to pass through the notch. The notch 10 has one end formed
with a protruding thread guide 13. The bobbin-accommodating
section 11 has an inner wall provided with a tensioning portion
(not shown) for tensioning the bobbin thread 59. The
tensioning portion includes an arc plate-shaped thread tension
bracket and an also arc plate-shaped thread tension spring
both of which are mounted on the inner wall of the bobbin
accommodating section 11 in a superposed state.
Next, the rotating hook 3 will be described. Referring
to FIGS. 5 and 6, the rotating hook 3 includes a cylindrical
receptacle-shaped hook body 4 having an open top, a beak member
5 to be mounted on the hook body 4 and a drive shaft 6 extending
downward from the central underside of the hook body 4. In
the embodiment, the hook body 4 and the drive shaft 6 are each
made of a synthetic resin such as nylon resin and are formed
integrally with each other, for example, by inj ection molding.
The beak member 5 is made of a synthetic resin such as polyimide
8
CA 02585434 2007-04-25
WO 2006/058230 PCT/US2005/042770
resin. The material of the beak member 5 has a higher hardness
than the material of the hook body 4.
The hook body 4 has a disc-shaped bottom 21 and an outer
circumferential wall 20 which is formed integrally with the
bottom so as to rise from an outer circumference of the bottom.
The hook body 4 has a slightly larger diameter than the bobbin
case holder 2. The hook body 4 includes a part formed into
a needle thread passing opening 22 through which a needle thread
caught by the beak member 5 passes, as shown in FIGS. 5 to
7. The wall 20 is further formed with an enlarged opening 23
(see FIG. 5) which is continuous to the opening 22 and into
which the beak member 5 is attached. The outer circumferential
wall 20 has an upper edge formed with an annular lace 24 having
an inner circumferential side lower by one step than the upper
edge. The outer periphery of the bobbin case holder 2 has a
lower end placed on the lace 24 so as to be slidable thereon
as shown in FIGS. 2 and 12, whereupon the bobbin case holder
2 is adapted to be accommodated in the rotating hook 3 while
floating slightly away from the bottom 21. Dashed line K in
FIGS. 10 and 11 designates a movement locus of the lower end
of the outer periphery of the bobbin case holder 2 sliding
on the lace 24.
Referring now to FIGS. 4 and 5, the drive shaft 6 is formed
into the shape of a pipe and has a shaft hole 6a vertically
extending therethrough. The drive shaft 6 further has a
worm-gear-like gear formed on the outer circumference thereof.
A rotating hook shaft (not shown) is adapted to be inserted
through the shaft hole 6a. The rotating hook shaft has a lower
end fixed to a sewing machine frame (the bottom of the bed
9
CA 02585434 2007-04-25
WO 2006/058230 PCT/US2005/042770
52), thereby rotatably supporting the rotating hook 3. The
gear of the drive shaft 6 is brought into mesh engagement with
a driving gear of a hook driving mechanism (not shown) so that
the rotating hook 3 is rotated via the aforesaid driving gear
and drive shaft 6 in the hook rotating direction A.
The beak member 5 is a component separate from the hook
body 4 and is detachably attached to the hook body 4 in the
embodiment. A mounting structure for the beak member 5 will
be described in detail. The construction of the beak member
5 will firstly be described. The beak member 5 has a height
equal to that of the outer circumferential wall 20 and is formed
into the shape of a plate curved at the same curvature as the
wall 20 as viewed from above, as shown in FIGS. 5 and 9 to
11. The beak member 5 is sized so as to close the aforesaid
enlarged opening 23. The beak member 5 has substantially a
lower half serving as a support wall 31 and an upper half serving
as a beak peripheral wall 32 located at the outer periphery
side of the lace 24.
The beak peripheral wall 32 has an upper face including
a forward side with respect to a rotation direction A of the
rotating hook as shown in FIG. 11. A guide face 32d is formed
on the forward side of the upper face of the beak peripheral
wall 32. The beak peripheral wall 32 further has a rearward
side upper end formed with an outwardly protruding thread
engagement step 32c. The thread engagement step 32c is
provided for engaging and locking the needle thread loop.
The beak peripheral wall 32 also has an inner periphery
including a horizontal thin plate-shaped beak body 33 formed
integrally with the wall 32 so as to be located near to the
CA 02585434 2007-04-25
WO 2006/058230 PCT/US2005/042770
lower side of the lace 24 (the side lower than the chain line
K) as shown in FIGS. 4, 6 and 9 to 11. The beak body 33 has
a forward side end with respect to the rotation direction A
of the rotating hook. The forward side end of the beak body
33 is formed so as to extend toward the forward side by a
predetermined dimension and so as to protrude inward. The beak
peripheral wall 32 and beak body 33 constitute the thread
capturing beak. Furthermore, two positioning pins 37 extend
downward from the underside of the support wall 31 of the beak
member 5 as shown in FIGS. 5 and 11.
A fixing block 34 is integrally formed on the inner
periphery of the support wall 31 as shown in FIG. 9. The fixing
block 34 includes a bottom 36 mounted on the lower end of the
support wall 31 and a pair of substantially triangular side
walls 35 extending from opposite ends of the bottom 36. The
bottom 36 is formed into a rectangular shape and has a centrally
located fixing screw hole 36a.
On the other hand, the hook body 4 is provided with a
fitting holder 43 for holding the beak member S. The fitting
holder 4 3 includes a reinforcing peripheral wall 4 1 protruding
outward from the outer peripheral wall 20 of the hook body
4 and supporting a lower outer face of the beak member 5 as
shown in FIGS. 7 and 8. The fitting holder 43 further includes
a reinforcing bottom 40 which is continuous to the bottom 21
and constitutes the bottom of the fitting holder 43.
Furthermore, the reinforcing peripheral wall 41 has an end
having an inner reinforcing wall 42 which is formed adjacent
to the inner face of the beak member 5 so as to be parallel
with the reinforcing peripheral wall 41. Each of the
11
CA 02585434 2007-04-25
WO 2006/058230 PCT/US2005/042770
peripheral walls 41 and 42 has a height set to about one third
of the height of the outer peripheral wall 20, for example.
The reinforcing peripheral wall 41 has both ends continuous
to the outer peripheral wall 20. Furthermore, the reinforcing
peripheral wall 41 has a corner located at the forward side
with respect to the rotation direction A of the rotating hook
as shown only in FIG. 7. A columnar corner support 41a is formed
on the corner so as to be located at the reinforcing bottom
40 side. Thus, the corner support 41a, reinforcing peripheral
wall 41 and inner reinforcing wall 42 are abutted against the
upwardly inserted beak member 5, thereby holding the beak
member 5 in a vertical position.
On the other hand, the reinforcing bottom 40 continuous
to the bottom 21 is formed into a generally T-shape as viewed
on a plane so as to be located slightly lower than the bottom
21. The reinforcing bottom 40 has a screw hole 40a formed an
inner part thereof so that the screw hole 40a corresponds to
the screw hole 36a of the fixing block 34 of the beak member
5. The reinforcing bottom 40 further has a circular pin hole
40b for positioning the beak member 5 and an elongate circular
pin hole 40c which is slightly longer laterally than the pin
hole 40b. The pin holes 40b and 40c are formed so as to
correspond to the aforesaid two positioning pins 37
respectively. A small fixing screw 38 is inserted upward
through the screw hole 40a to be screwed into the screw hole
36a of the fixing block 34 (see FIG. 5) , whereby the beak member
5 is fixed to the rotating hook 3.
A plurality of inclined faces 32a, 33a, 20a and 20b are
adapted to be formed when the beak member 5 and the rotating
12
CA 02585434 2007-04-25
WO 2006/058230 PCT/US2005/042770
hook 5 are injection-molded. More specifically, as shown in
FIG. 10, the first inclined face 32a is formed on a forward
end of the beak peripheral wall 32 with respect to the rotation
direction A of the rotating hook 3. The first inclined face
32a is inclined forwardly outward. The second inclined face
33a is formed on a forward end of the beak body 33 with respect
to the rotation direction A of the rotating hook 3 as shown
in FIG. 11. The second inclined face 33a is inclined forwardly
downward.
On the other hand, the third inclined face 20a is formed
on an edge of the outer peripheral wall 20 fronting to the
aforesaid enlarged opening 23 and the beak member 5 as shown
in FIGS. 6 and 10. The third inclined face 20a is inclined
forwardly outward. Furthermore, as shown in FIG. 11, the
fourth inclined face 20b is formed on a forward edge of the
lace 24. The fourth inclined face 20b is inclined forwardly
downward. As the result of provision of the inclined faces
32a, 32b, 20a and 20b, the bobbin case holder 2 is adapted
to slide on the lace 24 smoothly.
An operation and effect of the horizontal rotary hook
constructed above will now be described. The beak member 5
is mounted on the rotating hook 3 in the manner as described
below. Firstly, the beak member 5 is fitted with the fitting
holder 43 provided on the rotating hook 3 from above as shown
in FIG. 5. In this case, the beak member 5 is inserted while
being guided by the reinforcing peripheral wall 41 and inner
reinforcing wall 42. As a result, the positioning pins 37
formed on the lower end of the beak member 5 are inserted into
the pin holes 40b and 40c formed in the reinforcing bottom
13
CA 02585434 2007-04-25
WO 2006/058230 PCT/US2005/042770
40 respectively. Since the beak member 5 is thus fitted in
the fitting holder 43, the beak member 5 can easily be
positioned.
The pin hole 40c which is slightly longer laterally than
the pin hole 40b. Accordingly, even if the distance between
the positioning pins 37 has a dimensional error, the error
can be absorbed by the elongate pin hole 40c. Consequently,
the beak member 5 can be mounted on the rotating hook 5 reliably
and accurately, and productivity and workability can be
improved. Furthermore, since the beak member 5 is guided by
the reinforcing peripheral wall 41 and inner reinforcing wall
42 onto the reinforcing bottom 40 of the fitting holder 43,
the beak member 5 can readily be mounted on the rotating hook
3.
When the beakmember 5 is located on the reinforcing bottom
40, the fixing screws 38 of the beak member 5 are screwed into
the screw holes 40a and 36a respectively so that the beak member
5 is fixed via the fixing block 34 to the rotating hook 3.
Consequently, the beak member 5 is stably fixed to and reliably
mounted on the rotating hook 3. Furthermore, the two
positioning pins 37 are in engagement with the pin holes 40b
and 40c respectively. As a result, even when the beak member
5 is instantaneously subjected to an external stress caused
by thread entanglement or the like and acting outward, the
strength of the beakmember 5 can be increased so as to withstand
the stress.
Moreover, in this case, the corner support 41a,
reinforcing peripheral wall 41 and inner reinforcing wall 42
are constructed to be caused to abut against the beak member
14
CA 02585434 2007-04-25
WO 2006/058230 PCT/US2005/042770
5, thereby holding the beak member 5 in a vertical position.
More specifically, the outer surface of the beak member 5 abuts
against the inner surface of the reinforcing peripheral wall
41, and the forward side of the beak member 5 with respect
to the rotation direction A of the rotating hook 3 abuts against
the corner support 41a from inside. The inner surface of the
forward side of the beak member 5 with respect to the rotation
direction A of the rotating hook 3 abuts against the inner
reinforcing wall 42 from outside. Accordingly, the beak
member 5 is reinforced as the result of the abutment against
the corner support 41a, reinforcing peripheral wall 41 and
inner reinforcing wall 42. Consequently, the strength
overcoming the aforesaid external stress can be ensured.
Furthermore, since the beak member 5 is fixed to the
rotating hook 3 by the fixing screw 38, only the beak member
5 can easily be replaced as occasion demands. As a result,
the replacement can render the replacement cost lower than
the replacement of the whole rotating hook 3. Since a synthetic
resin is employed as the material for the beak member 5, the
beak member can readily be formed into a product. The synthetic
resin can reduce the production cost of the beak member 5 as
compared with the beak member is made of a metal. More
specifically, since the rotating hook 3 is made of a nylon
resin and the beak member 5 is made of a polyimide resin having
a higher hardness than the nylon resin, a sufficient hardness
can be ensured for the beak member 5. Additionally, the
production cost can be reduced in this case as compared with
the case where the whole rotating hook 3 is made of the polyimide
resin.
CA 02585434 2007-04-25
WO 2006/058230 - PCT/US2005/042770
Furthermore, the enlarged opening 23 is formed so as to
be continuous to the needle-thread passing opening 22. The
beak member 5 is mounted on the rotating hook 3 so as to close
the enlarged opening 23. Accordingly, the thickness of the
outer peripheral wall 20 need not be increased. Thus, the beak
member 5 and the rotating hook 3 can be composed as discrete
components while the size of the rotating hook 3 is prevented
from being increased. Furthermore, even when the beak member
5 and the rotating hook 3 are separate from each other, the
outer peripheral wall 20 of the rotating hook 3 can be extended
by the beak peripheral wall 32, whereupon the needle thread
can reliably be captured. Additionally, the beak body 33 is
formed so as to extend toward the forward side by the
predetermined dimension and so as to protrude inward.
Consequently, the needle thread can be captured more
effectively and more reliably.
In a sewing operation, the rotating hook 3 is rotated
in the rotation direction A by a hook driving mechanism (not
shown) such that the bobbin case holder 2 is rotated relative
to the rotating hook 3 while being supported on the lace 24
(see FIG. 12).
The beak peripheral wall 32 is located outside the lace
24 of the rotating hook 3 (outside the chain line K) and is
continuous to the outer peripheral wall 20. Consequently, the
bobbin case holder 2 can smoothly be rotated without
interference with the beak peripheral wall 32.
The thread guide 13 of the bobbin case holder 2 is
prevented from colliding with the beak peripheral wall 32 and
beak body 33 when passing over the beak body 33. More
16
CA 02585434 2007-04-25
WO 2006/058230 PCT/US2005/042770
specifically, the beak peripheral wall 32 is formed with the
first inclined face 32a and the beak body 33 is formed with
the second inclined face 33a. Each inclined face is located
at the forward side of the beak member 5 with respect to the
rotation direction A of the rotating hook 3. Since the thread
guide 13 is guided by the inclined faces 32a and 33a, the thread
guide 13 of the bobbin case holder 2 can smoothly pass over
the beak member S.
Furthermore, the thread guide 13 can be prevented from
colliding with the forward side edge of the outer peripheral
wall 20 when passing the forward side edge of the outer
peripheral wall 20. More specifically, the forward side edge
of the outer peripheral wall 20 is formed with the third and
fourth inclined faces 20a and 20b both located at the forward
side with respect to the rotation direction A of the rotating
hook 3. Since the thread guide 13 is guided by the third and
fourth inclined faces 20a and 20b, the thread guide 13 can
smoothly pass the forward edge of the outer peripheral wall
20.
Several modified forms of the foregoing embodiment will
now be described. The beak member 5 may be made of a metal,
instead. Three or more positioning pins 37 may be formed on
the beak member 5. Also, three or more pin holes may be formed
in the reinforcing bottom 40. When a sufficient space is
allowed to be provided around the rotating hook 3, the
reinforcing peripheral wall 41 may have a height increased
up to about a half of a height of the outer peripheral wall
20. In this case, the reinforcement strength of the beakmember
5 can further be improved.
17
CA 02585434 2007-04-25
WO 2006/058230 PCT/US2005/042770
The foregoing description and drawings are merely
illustrative of the principles of the present invention and
are not to be construed in a limiting sense. Various changes
and modifications will become apparent to those of ordinary
skill in the art. All such changes and modifications are seen
to fall within the scope of the invention as defined by the
appended claims.
18
