TECHNICAL FIELD
[0001] This disclosure relates to a bobbin case removing and attaching mechanism for a loop
taker mounted at a sewing apparatus.
BACKGROUND DISCUSSION
[0002] A known bobbin case removing and attaching mechanism for a loop taker mounted at
a sewing apparatus is disclosed in JPS57-38278B (hereinafter referred to as Reference
1). The loop taker disclosed in Reference 1 includes a movable rotation stopper having
two engagement pieces, at least one of which engages with a bobbin case. The loop
taker also includes an operation member rotatably connected to a pin that is fixed
to a sewing machine bed. One end of the operation member is normally positioned to
be slightly away from the movable rotation stopper. The operation member includes
an operation portion that is operated by a protrusion formed at a position restricting
member of the bobbin case in a case where the position restricting member moves to
a release position. The operation member releases the engagement between one of the
engagement pieces of the movable rotation stopper and the bobbin case by means of
the operation portion regardless of a rotational phase of the loop taker. In addition,
the operation member causes the other of the engagement pieces of the movable rotation
stopper to be positioned at an upper side of a release portion of the bobbin case.
According to the aforementioned bobbin case removing and attaching mechanism, in a
case where the position restricting member is slid to a position where the protrusion
of the position restricting member makes contact with the operation portion, a bobbin
is removable from the bobbin case. However, the bobbin case is not removable from
the loop taker. In a case where the position restricting member is further slid in
the aforementioned direction from the position where the protrusion of the position
restricting member makes contact with the operation portion, the bobbin case removing
and attaching mechanism is activated, thereby engaging the protrusion with the operation
portion and pressing the operation portion. Because the operation portion is pressed,
the movable rotation stopper rotates to release the engagement between the bobbin
case and the movable rotation stopper. As a result, the bobbin case is removable from
the loop taker. On the other hand, in a case where the bobbin case is inserted to
the loop taker so as to be attached thereto, one of the engagement pieces is inserted
into a groove formed at the bobbin case. Thus, a failure of the arrangement position
of the bobbin case at the loop taker is unlikely to occur.
[0003] In addition, a known sewing machine is disclosed in JPH03-14478B (hereinafter referred
to as Reference 2). The sewing machine includes a sewing machine bed, a loop taker
arranged for rotation about a vertical axis and accommodated within the bed, the loop
taker having a rim that extends in a direction perpendicular to the vertical axis
and an open ended hollow cavity of which an end opens towards the rim, and a bobbin
case arranged within the loop taker and having a flange. The sewing machine also includes
a bracket removably attached to the bed and having an opening at a center, the bracket
restraining a movement of the bobbin case within the cavity and providing a clearance
for a passage of a thread relative to the bobbin case. The bracket is placed on one
end surface of the flange of the bobbin case at two portions. The sewing machine further
includes a first support portion provided at the bracket and positioned on one side
of a plane containing the vertical axis of the loop taker, and a second support portion
positioned on the rim and having less than 180° of angular displacement, the second
support portion being positioned on the other side of the plane together with the
two portions of the bracket. The sewing machine still further includes a vertical
wall provided at the first support portion so as to make contact with the bobbin case.
According to the aforementioned sewing machine, the bobbin case is retained in operational
engagement with the rim. The bobbin case is removed from an operating position at
the loop taker after the bracket is removed therefrom. A recess is formed at one of
the two portions of the bracket that is placed on the end surface of the flange of
the bobbin case. A tab is formed at the flange of the bobbin case so as to engage
with the recess. As a result, the rotational movement of the bobbin case is restricted.
[0004] According to Reference 1, although the bobbin case is unlikely to be arranged at
a wrong position at the loop taker when the bobbin case is inserted into the loop
taker, it is difficult to observe one of the engagement pieces because the engagement
piece is arranged below a needle plate. Therefore, it is difficult to insert the engagement
piece into the groove of the bobbin case, which may hinder the arrangement of the
bobbin case at the loop taker. In addition, in order to remove or attach the bobbin
case relative to the loop taker, a number of components constituting a complex link
mechanism are provided around the loop taker. As a result, accurate positioning of
the components is difficult because of manufacturing tolerances of the components.
Further, a cost of the bobbin case removing and attaching mechanism may increase due
to the complex structure thereof.
[0005] According to Reference 2, it is difficult for a user to arrange the bobbin case at
the loop taker because with reference to what the bracket is positioned is unclear.
In a case where the user fixes the bobbin case by a screw at a wrong position in the
loop taker, an appropriate sewing may not be obtained because of the wrong arrangement
of the bobbin case at the loop taker. Further, in order to clear up lint or waste
accumulated in the loop taker, the needle plate, the bracket, and then the bobbin
case are removed. The removal of the three components may lead to a complicated operation
for removing the bobbin case.
[0006] A need thus exists for a bobbin case removing and attaching mechanism for a loop
taker which achieves easy removal and attachment of a bobbin case by removing only
a needle plate. In addition, the bobbin case is inserted into a predetermined operating
position at a loop taker when the bobbin case is attached to the loop taker, and the
bobbin case is retained at the predetermined operating position even under a vibration
or other forces generated upon sewing (for example, a force generated when a sewing
apparatus is carried or transferred, and the like). Further, the bobbin case removing
and attaching mechanism for the loop taker is obtained at low costs.
SUMMARY
[0007] According to an aspect of this disclosure, a bobbin case removing and attaching mechanism
for a loop taker includes a loop taker arranged within a work supporting bed for a
sewing apparatus and rotatable about an axis of the loop taker, a bobbin case inserted
into a bobbin case accommodating portion formed at the loop taker, the bobbin case
accommodating portion upwardly opening, a bracket mounted at a fixing member that
is arranged at the work supporting bed and including an opening where the bobbin case
passes through when the bobbin case is inserted to or removed from the bobbin case
accommodating portion, and a needle plate attached at an upper portion of the bracket
and closing at least a portion of the opening of the bracket, the needle plate including
a bobbin case stopper piece restricting an upward movement of the bobbin case that
is inserted into the bobbin case accommodating portion and arranged at an operating
position thereof. The bobbin case that is inserted into the bobbin case accommodating
portion is retained at the operating position while a movement of the bobbin case
is restricted by the bracket and the bobbin case stopper piece in a state where the
needle plate is attached to the bracket. In addition, the bobbin case is removed from
or attached to the bobbin case accommodating portion in a state where the needle plate
is removed from the bracket and the bracket is fixed to the fixing member.
[0008] According to the aforementioned disclosure, the needle plate is removed in a state
where the bracket is fixed to the fixing member to thereby remove or attach the bobbin
case relative to the bobbin case accommodating portion of the loop taker. Therefore,
the removing and attaching of the bobbin case is simply performed and operability
thereof may increase.
[0009] In addition, during a sewing operation, a vibration is constantly generated so as
to dislocate the bobbin case from the operating position at the loop taker. In addition,
when the sewing apparatus is carried or transferred, a force for dislocating the bobbin
case from the operating position may occur because of the vibration, and the like.
In a case where the aforementioned vibration or the force is generated, the bobbin
case is retained at the predetermined operating position in the loop taker because
the bobbin case is restrained from moving by the bracket and the bobbin case stopper
piece. As a result, the bobbin case is restrained from moving so as to be positioned
on an upper surface of the loop taker. Appropriate stitches may be obtained according
to the aforementioned bobbin case removing and attaching mechanism.
[0010] Further, according to the aforementioned bobbin case removing and attaching mechanism,
the operating position of the bobbin case is restricted by the bracket and the bobbin
case stopper piece, thereby simplifying the configuration of the mechanism and obtaining
a reduced manufacturing cost.
[0011] The bracket includes a rotation restricting portion restricting an insertion direction
of the bobbin case and restricting a rotation of the bobbin case, and a guide portion
making contact with a portion of an upper side surface of the bobbin case in a case
where the bobbin case is inserted into the bobbin case accommodating portion and restricting
an upward movement of the bobbin case, and wherein clearances through each of which
a needle thread passes are formed between the rotation restricting portion and the
bobbin case and between the guide portion and the bobbin case respectively.
[0012] Accordingly, in a case where the bobbin case is inserted into the bobbin case accommodating
portion of the loop taker in a state where the needle plate is removed therefrom,
the position of the bobbin case in the rotational direction is restricted by the rotation
restricting portion while the insertion position of the bobbin case in the upward
direction is restricted by the guide portion. As a result, the bobbin case is insertable
only in a predetermined direction to the predetermined operating position in the bobbin
case accommodating portion of the loop taker. The bobbin case that is inserted into
the bobbin case accommodating portion is removable only from a direction opposite
from the aforementioned predetermined direction. Thus, a user easily inserts the bobbin
case to the predetermined operating position in the loop taker and easily removes
the bobbin case from the loop taker. A broken thread because of a blocking of a path
of a needle thread, and the like, that occurs in a case where the bobbin case is dislocated
from the predetermined operating position, may be restrained to thereby achieve appropriate
stitches.
[0013] Further, the movement of the bobbin case in the rotational direction is restricted
by the rotation restricting portion under a vibration force generated in the sewing
apparatus during the sewing operation or the force generated when the sewing apparatus
is carried or transferred. The upward movement of the bobbin case is restricted by
the guide portion and the bobbin case stopper piece. Therefore, the bobbin case is
retained at the predetermined operating position in the bobbin case accommodating
portion of the loop taker. As a result, the bobbin case is restrained from moving
so as to be positioned on the upper surface of the lop taker, thereby achieving the
appropriate stitches.
[0014] The guide portion is formed by a downward bending of a portion at an edge of the
opening of the bracket.
[0015] Accordingly, the simple structured and low cost bobbin case removing and attaching
mechanism for the loop taker is obtained.
[0016] The bobbin case stopper piece includes elasticity to press the bobbin case.
[0017] Accordingly, a dimensional tolerance between the needle plate and the bobbin case
may be absorbed by means of the elasticity.
[0018] The bobbin case stopper piece is formed separately from the needle plate and is removably
fixed to a lower surface of the needle plate.
[0019] Accordingly, a structure of the needle plate may be simplified as compared to a case
where the bobbin case stopper piece is integrally formed with the needle plate.
[0020] The bobbin case stopper piece is an elongated member made of metal and fixed to the
lower surface of the needle plate in a cantilever manner.
[0021] Accordingly, the elasticity of the bobbin case stopper piece is adjustable by changing
a length of the bobbin case stopper piece. In a case where the bobbin case stopper
piece is made of metal, an increase of dimensions of the bobbin case stopper piece
is avoidable as compared to a case where the bobbin case stopper piece is formed by
a resin molding.
[0022] The bobbin case stopper piece is formed separately from the needle plate, the bobbin
case stopper piece including a base portion fixed to the lower surface of the needle
plate and a free end portion being apart from the lower surface of the needle plate
by a predetermined distance.
[0023] That structure of the needle plate may be simplified as compared to a case where
the bobbin case stopper piece is integrally formed with the needle plate. An appropriate
change of a length between the free end portion and the lower surface of the needle
plate may adjust a magnitude of the elasticity of the bobbin case stopper piece.
[0024] The bobbin case stopper piece is made of metal.
[0025] In a case where the bobbin case stopper piece is made of metal, the increase of dimensions
of the bobbin case stopper piece is avoidable as compared to the case where the bobbin
case stopper piece is formed by the resin molding.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] The foregoing and additional features and characteristics of this disclosure will
become more apparent from the following detailed description considered with the reference
to the accompanying drawings, wherein:
[0027] Fig. 1 is an exploded perspective view of a bobbin case removing and attaching mechanism
for a loop taker according to an embodiment;
[0028] Fig. 2 is a perspective view of a bracket illustrated in Fig. 1 when viewed from
a lower side of Fig. 1;
[0029] Fig. 3 is a plan view in a state where a needle plate is removed from the bobbin
case removing and attaching mechanism;
[0030] Fig. 4 is a plan view of the bobbin case removing and attaching mechanism;
[0031] Fig. 5 is a cross-sectional view taken along the line V-V illustrated in Fig. 4;
and
[0032] Fig. 6 is a perspective view illustrating a positional relationship between a bobbin
case, the bracket, and a bobbin case stopper piece.
DETAILED DESCRIPTION
[0033] An embodiment will be explained with reference to the attached drawings.
[0034] As illustrated in Fig. 1, a bobbin case removing and attaching mechanism 10 (a bobbin
case removing and attaching mechanism for a loop taker) includes a loop taker 1 mounted
at an inner side of a carrier plate 3 (fixing member) that is attached to a sewing
machine bed (a work supporting bed) of a sewing machine (a sewing apparatus), a bracket
4 fixed to a flange 31 of the carrier plate 3, a bobbin case 2 inserted into the loop
taker 1, and a needle plate 5 fixed to an upper surface 4a of the bracket 4.
[0035] The loop taker 1 is formed substantially into a cylindrical shape constituted by
a cylindrical portion which is partially cut out and a bottom portion. The loop taker
1 includes a bobbin case accommodating portion 13 of which an upper side in Fig. 1
opens, a notch end 14 formed at a portion of the cylindrical portion, an upper surface
12, and a race surface 11 I formed at an upper side of the cylindrical portion. In
a case where the loop taker 1 rotates about a rotational axis Z (an axis) (see Fig.
5) thereof in a counterclockwise direction when viewed from an upper side in Fig.
5, the notch end 14 catches a needle thread, thereby forming stitches.
[0036] The bobbin case 2 includes a bobbin accommodating portion 23 of which an upper side
in Fig. 1 opens so as to accommodate a bobbin on which a bobbin thread is wound. A
portion of an upper side wall of the bobbin accommodating portion 23 is cut to form
into a thin shape to thereby obtain a bobbin removing portion 22. A flange surface
29 that makes contact with the race surface 11 of the loop taker 1 is formed at an
outer peripheral surface 28b of the bobbin case 2. The outer peripheral surface 28b
is formed to be perpendicular to an inner peripheral surface 28a of the bobbin case
2. The bobbin is accommodated at the inner peripheral surface 28a at an axially intermediate
portion of the bobbin case 2. A protruding portion 21 is formed at a portion of the
outer peripheral surface 28b that faces a connecting portion between the bobbin removing
portion 22 and the bobbin accommodating portion 23. Then, an inclination portion 26
including ribs 26a, 26b, 26c, and 26d (see Figs. 1 and 3) is formed at a portion of
the outer peripheral surface 28b at substantially 90° relative to the protruding portion
21 in a clockwise direction as seen in Fig. 1. A radially outer surface of the rib
26a forms a reverse rotation stopper surface 24 (see Figs. 1, 3 and 6) that is parallel
to an axis of the inner peripheral surface 28a and is perpendicular to a feeding direction
of a feed dog 7. The reverse rotation stopper surface 24 is parallel to an arrow A
in Fig. 3. In addition, a plane surface portion 25 (i.e., a portion of an upper side
surface of the bobbin case 2) is formed to be perpendicular to the reverse rotation
stopper surface 24. The plane surface portion 25 is positioned to be lower than an
upper-right portion (an upper-right surface portion) 27 of the bobbin case 2 formed
at the bobbin removing portion 22. At this time, the plane surface portion 25, the
inclination portion 26, and the upper-right portion 27 constitute the upper side surface
of the bobbin case 2.
[0037] The carrier plate 3 is formed into a channel shape by a bending of a plate member.
The carrier plate 3 includes the flanges 31 at upper left and right sides in Fig.
1. Internal threads 32 are formed at the flanges 31 so as to secure the bracket 4.
[0038] As illustrated in Fig. 2, the bracket 4 is formed by a plate member that is bent.
The bracket 4 includes an opening 45 at a center. A thread release portion 44 serving
as a rotation restricting portion and a support portion 40 serving as a portion of
an opening edge are formed at a rear surface 4b of the bracket 4. The support portion
40 is bent to be substantially perpendicular to the rear surface 4b. The support portion
40 includes a rotation direction support portion 42 serving as the rotation restricting
portion and a vertical direction support portion 41 serving as a guide portion. The
rotation direction support portion 42 is provided at a right side in the support portion
40 in Fig. 2 (i.e., a side surface at a front side of the sewing apparatus) so as
to be perpendicular to the rear surface 4b. The vertical direction support portion
41 is formed at a lower surface of the bracket 4 perpendicular to the rotation direction
support portion 42 (i.e., a lower surface parallel to the rear surface 4b). In addition,
an elongated bore 46 opens at the rear surface 4b in the vicinity of the rotation
direction support portion 42. Then, a vertical direction sub-support portion 43 (see
a shaded portion in Fig. 2) is formed at an edge of the rear surface 4b along a longitudinal
direction of the elongated bore 46.
[0039] The vertical direction support portion 41 is formed and positioned in such a manner
that the plane surface portion 25 of the bobbin case 2 can be inserted into a space
formed between the vertical direction support portion 41 and the race surface 11 of
the loop taker 1 from an obliquely upward side of the opening 45 to an obliquely downward
side thereof in the arrow A direction (see Fig. 3). That is, according to the present
embodiment, the vertical direction support portion 41 is formed at a distant portion
of a peripheral edge of the opening 45 in a direction from which the bobbin case 2
is inserted.
[0040] The vertical direction sub-support portion 43 is formed and positioned in such a
manner that the inclination portion 26 of the bobbin case 2 can be inserted into a
space formed between the vertical direction sub-support portion 43 and the race surface
11 of the loop taker 1 from the obliquely upward side of the opening 45 to the obliquely
downward side thereof in the arrow A direction (see Fig. 3). That is, according to
the present embodiment, the vertical direction sub-support portion 43 is formed at
a closer portion of the peripheral edge of the opening 45 in the direction from which
the bobbin case 2 is inserted.
[0041] The bracket 4 includes four bores 47 into which bracket stopper screws 48 (see Fig.
1) are inserted and two internal threads 49 with which needle plate fixing screws
53 (see Fig. 1) are meshed.
[0042] As illustrated in Fig. 1, the needle plate 5 includes an opening 51 having substantially
a U-shape, bores 52 into which the needle plate fixing screws 53 are inserted, and
multiple opening grooves 54 for the feed dog 7. The needle plate 5 also includes a
bobbin case stopper piece 6. One end (i.e., a base portion) of the bobbin case stopper
piece 6 is attached or fixed to a rear surface 5b (lower surface) of the needle plate
5 in Fig. 1 while the other end (i.e., a free end portion, which is apart from the
rear surface 5b of the needle plate 5 by a predetermined distance) of the bobbin case
stopper piece 6 is positioned within the opening 51. In a case where the needle plate
5 is mounted at the bracket 4, the other end of the bobbin case stopper piece 6 extends
over the upper-right portion 27 of the bobbin case 2. At this time, the other end
of the bobbin case stopper piece 6 desirably extends beyond an outer edge of the upper-right
portion 27 that is positioned in the vicinity of an inner side surface 45a of the
opening 45 formed at a front side thereof as illustrated in Fig. 6. The bobbin case
stopper piece 6 is provided to restrict an upward movement of the bobbin case 2 that
is inserted into the bobbin case accommodating portion 13 of the loop taker 1. In
addition, the bobbin case stopper piece 6 includes elasticity to press the bobbin
case 2. Further, the bobbin case stopper piece 6 may be formed separately from the
needle plate 5 and be removably fixed to the rear surface 5b of the needle plate 5.
The bobbin case stopper piece 6 may be an elongated member made of metal and fixed
to the rear surface 5b of the needle plate 5 in a cantilever manner.
[0043] Next, an assembly procedure of the bobbin case removing and attaching mechanism 10
will be explained with reference to Figs. 1, 3, 5, and 6.
[0044] As illustrated in Fig. 1, the loop taker 1 is mounted at the carrier plate 3 fixed
to the sewing machine bed of the sewing apparatus and is connected to a main shaft
thereof that rotates the loop taker 1 in a counterclockwise direction when viewed
from an upper side in Fig. 1. Then, the bracket stopper screws 48 inserted into the
bores 47 of the bracket 4 are meshed with the internal threads 32 formed at the flanges
31 of the carrier plate 3, thereby fixing the bracket 4 to the flanges 31.
[0045] Afterwards, as illustrated in Figs. 1 and 3, the bobbin case 2 is moved from the
obliquely upward side (according to the embodiment, from the obliquely rightward and
upward side) of the opening 45 of the bracket 4 in the arrow A direction towards the
obliquely downward side (according to the embodiment, towards the obliquely leftward
and downward side) of the opening 45 in a state where the reverse rotation stopper
surface 24 of the bobbin case 2 is positioned to be substantially parallel to the
arrow A, so that the bobbin case 2 is inserted into the bobbin case accommodating
portion 13 of the loop taker 1. At this time, the bobbin case 2 is inserted into the
loop taker 1 only in the arrow A direction in Fig. 3, i.e., from the obliquely upward
side to the obliquely downward side of the opening 45, which will be explained later
in details.
[0046] After the bobbin case 2 is inserted into the loop taker 1, the needle plate 5 is
attached to the upper surface 4a of the bracket 4 as illustrated in Figs. 1 and 4.
The needle plate fixing screws 53 inserted into the bores 52 of the needle plate 5
are meshed with the internal threads 49 (see Figs. 1 and 2) to thereby fix the needle
plate 5 to the bracket 4. Consequently, the assembly of the bobbin case removing and
attaching mechanism 10 is completed. The bobbin case 2 is removable from the bobbin
case accommodating portion 13 of the loop taker 1 by being pulled to the obliquely
upward side (according to the embodiment, to the obliquely rightward and upward side)
of the opening 45, specifically, in a direction of an arrow B (see Fig. 3) opposite
from the arrow A, after the needle plate 5 is removed from the bracket 4, which will
be explained later.
[0047] A positional relationship between the bobbin case 2 mounted at the bobbin case accommodating
portion 13 of the loop taker 1 and the bobbin case stopper piece 6 provided at the
loop taker 1 and the needle plate 5 is as follows. As illustrated in Figs. 1 and 5,
the flange surface 29 of the bobbin case 2 is seated on or contactable with an upper
portion of the race surface 11 of the loop taker 1. At this time, a clearance is formed
between the upper-right portion 27 of the bobbin case 2 and a bottom surface 6b of
the bobbin case stopper piece 6 so that the needle thread easily passes through the
clearance. In the vicinity of a portion where the upper-right portion 27 of the bobbin
case 2 is contactable with the bottom surface 6b of the bobbin case stopper piece
6, the vertical movement of the bobbin case 2 is limited to an extent of the size
of the clearance through which the needle thread passes, thereby restricting the vertical
movement of the bobbin case 2. In addition, because of a contact between the flange
surface 29 of the bobbin case 2 and the race surface 11 of the loop taker 1, the downward
movement of the bobbin case 2 is restricted by the race surface 11.
[0048] As illustrated in Figs. 3, 4, and 6, a clearance through which the needle thread
passes is formed between the protruding portion 21 of the bobbin case 2 and the thread
release portion 44 of the bracket 4. Thus, in a case where the protruding portion
21 of the bobbin case 2 makes contact with the thread release portion 44, the rotational
movement of the bobbin case 2 in the counterclockwise direction when viewed from the
upper side of the bobbin case 2 is limited to the size of the clearance through which
the needle thread passes, thereby restricting the rotational movement of the bobbin
case 2 in the counterclockwise direction.
[0049] As illustrated in Figs. 3 and 6, a clearance through which the needle thread passes
is formed between the reverse rotation stopper surface 24 of the bobbin case 2 and
the rotation direction support portion 42 of the bracket 4. Thus, in a case where
the reverse rotation stopper surface 24 of the bobbin case 2 makes contact with the
rotation direction support portion 42, the rotational movement of the bobbin case
2 in the clockwise direction when viewed from the upper side of the bobbin case 2
is limited to the size of the clearance through which the needle thread passes, thereby
restricting the rotational movement of the bobbin case 2 in the clockwise direction.
[0050] As illustrated in Figs. 1 and 6, a clearance through which the needle thread passes
is formed between the plane surface portion 25 of the bobbin case 2 and the vertical
direction support portion 41 of the bracket 4. Thus, in a case where the plane surface
portion 25 of the bobbin case 2 makes contact with the vertical direction support
portion 41 (i.e., the vertical direction support portion 41 is in contact with a portion
of an upper side surface of the bobbin case 2), the upward movement of the bobbin
case 2 in the vicinity of the vertical direction support portion 41 is limited to
an extent of the size of the clearance, thereby restricting the upward movement of
the bobbin case 2.
[0051] As illustrated in Figs. 1 and 6, a clearance through which the needle thread passes
is formed between the inclination portion 26 of the bobbin case 2 and the vertical
direction sub-support portion 43 of the bracket 4. Thus, in a case where the inclination
portion 26 of the bobbin case 2 makes contact with the vertical direction sub-support
portion 43, the upward movement of the bobbin case 2 in the vicinity of the vertical
direction sub-support portion 43 is limited to the size of the clearance, thereby
restricting the upward movement of the bobbin case 2.
[0052] Accordingly, an operating position of the bobbin case 2 in the upward direction is
retained by the contact of the bottom surface 6b of the bobbin case stopper piece
6, the vertical direction support portion 41 of the bracket 4, and the vertical direction
sub-support portion 43 of the bracket 4 with three portions of the bobbin case 2 respectively.
An operating position of the bobbin case 2 in the downward direction is retained by
the contact between the flange surface 29 of the bobbin case 2 and the race surface
11 of the loop taker 1. An operating position of the bobbin case 2 in the rotational
direction is retained by the contact between the reverse rotation stopper surface
24 and the rotation direction support portion 42, and the contact between the protruding
portion 21 and the thread release portion 44.
[0053] Normally in the sewing apparatus having the loop taker, the bobbin case is first
positioned relative to the loop taker. The position of the bobbin case in the rotational
direction is defined by a positioning member, thereby arranging the bobbin case at
the operating position appropriate to form stitches. In case of removing lint or waste
accumulated in the loop taker, the bobbin case is removed from the loop taker so that
the lint or waste can be cleared away. After the removal of the lint or waste, the
bobbin case is again reattached to a predetermined position at the loop taker. According
to the bobbin case removing and attaching mechanism 10 of the present embodiment,
in the same way as a known loop taker, the bobbin case 2 is removed from the bobbin
case accommodating portion 13 of the loop taker 1 so as to clear away the lint or
waste within the bobbin case accommodating portion 13 of the loop taker 1. After the
bobbin case accommodating portion 13 is cleaned, the bobbin case 2 that is removed
should be reattached to the predetermined operating position of the loop taker 1.
The removal and attachment of the bobbin case 2 is conducted as follows.
[0054] In order to clean the bobbin case accommodating portion 13 of the loop taker 1, the
needle plate fixing screws 53 are unscrewed by a screw driver attached to the sewing
apparatus so as to remove the needle plate 5 from the bracket 4. Once the needle plate
5 is removed, substantially a full upper portion of the bobbin case 2 that is half
covered by the needle plate 5 is visually confirmable as illustrated in Fig. 3. The
bobbin case 2 is pulled out to the obliquely upward side of the opening 45, i.e.,
in the arrow B direction, so as to remove the bobbin case 2 from the bobbin case accommodating
portion 13. The lint or waste within the loop taker 1 is removed to thereby complete
the cleaning. The removal of the bobbin case 2 is achievable only in the aforementioned
direction (i.e., the arrow B direction).
[0055] After the cleaning of the bobbin case accommodating portion 13, the bobbin case 2
is reattached to the predetermined position at the loop taker 1 and thereafter the
needle plate 5 is attached to the bracket 4. In case of reattaching the bobbin case
2 to the predetermined position of the loop taker 1, the bobbin case 2 is moved from
the obliquely upward side of the opening 45 to the obliquely downward side thereof
in the arrow A direction to thereby insert the bobbin case 2 to the bobbin case accommodating
portion 13 of the loop taker 1. Such insertion is achievable because of the shapes
of the protruding portion 21, the reverse rotation stopper surface 24, and the plane
surface portion 25 of the bobbin case 2 and the shapes of the vertical direction support
portion 41 and the rotation direction support portion 42 of the bracket 4. Accordingly,
the bobbin case 2 is reattached to the previous position before being removed, i.e.,
the predetermined operating position at the bobbin case accommodating portion 13.
The insertion (attachment) of the bobbin case 2 is achievable only in the aforementioned
direction (i.e., the arrow A direction). Specifically, the insertion direction and
the removal direction of the bobbin case 2 relative to the loop taker 1 is limited
in the arrow A direction from the obliquely upward side of the opening 45 and in the
arrow B direction to the obliquely upward side of the opening 45 respectively.
[0056] That is, according to a first restriction manner, the clearance through which the
needle thread easily passes is formed between the projecting portion 21 of the bobbin
case 2 and the thread release portion 44 of the bracket 4. The rotation of the bobbin
case 2 is restricted within the size of the clearance through which the needle thread
passes. The rotation of the bobbin case 2 in the counterclockwise direction when viewed
from the upper side of the bobbin case 2 is restricted by the contact between the
protruding portion 21 of the bobbin case 2 with the thread release portion 44 of the
bracket 4.
[0057] According to a second restriction manner, the clearance through which the needle
thread easily passes is formed between the reverse rotation stopper surface 24 of
the bobbin case 2 and the rotation direction support portion 42 of the support portion
40 of the bracket 4. The rotation of the bobbin case 2 is restricted within the size
of the clearance through which the needle thread passes. The rotation of the bobbin
case 2 in the clockwise direction when viewed from the upper side of the bobbin case
2 is restricted by the contact between the reverse rotation stopper surface 24 of
the bobbin case 2 with the rotation direction support portion 42 of the support portion
40 of the bracket 4. According to the first and second restriction manners, the position
of the bobbin case 2 in the rotational direction is restricted and thus the direction
where the bobbin case 2 is inserted into the bobbin case accommodating portion 13
of the loop taker 1 is limited to the arrow A direction.
[0058] According to a third restriction manner, the plane surface portion 25 of the bobbin
case 2 is specified so that the clearance through which the needle thread easily passes
is formed relative to the vertical direction support portion 41 of the support portion
40 of the bracket 4. Thus, the upward movement of the bobbin case 2 in the vicinity
of the vertical direction support portion 41 is limited to the size of the clearance
through which the needle thread passes. The plane surface portion 25 of the bobbin
case 2 makes contact with the vertical direction support portion 41 of the support
portion 40 of the bracket 4, and the direction where the bobbin case 2 is removed
from and attached to the bobbin case accommodating portion 13 is restricted to the
obliquely upward side of the opening 45 as illustrated in Figs. 1 and 6. As a result,
the plane surface portion 25 is inserted into the space formed between the vertical
direction support portion 41 and the race surface 11 of the loop taker 1.
[0059] According to a fourth restriction manner, the inclination portion 26 of the bobbin
case 2 is specified so that the clearance through which the needle thread easily passes
is formed relative to the vertical direction sub-support portion 43 of the bracket
4. The upward movement of the bobbin case 2 in the vicinity of the vertical direction
sub-support portion 43 is limited to the size of the clearance. The inclination portion
26 makes contact with the vertical direction sub-support portion 43 of the bracket
4, and the direction where the bobbin case 2 is removed from and attached to the bobbin
case accommodating portion 13 is restricted to the obliquely upward side of the opening
45. As a result, the inclination portion 26 is inserted into the space formed between
the vertical direction sub-support portion 43 and the race surface 11 of the loop
taker 1. According to the third and fourth restriction manners, in a case where the
bobbin case 2 is inserted into the bobbin case accommodating portion 13 of the loop
taker 1, the insertion direction of the bobbin case 2 in the vertical direction is
limited from the obliquely upward side of the opening 45 to the obliquely downside
thereof. According to the first to fourth restriction manners, the insertion of the
bobbin case 2 to the loop taker 1 is restricted in the arrow A direction from the
obliquely upward side of the opening 45 to the obliquely downward side thereof. In
the same way, the removal direction of the bobbin case 2 is restricted in the arrow
B direction from the obliquely downward side of the opening 45 to the obliquely upward
side thereof.
[0060] According to the present embodiment, either the third restriction manner or the fourth
restriction manner may be applied. In a case where one of the third and fourth restriction
manners is selected, the third restriction manner is more desirable than the fourth
restriction manner because the contact is obtained by the two surfaces parallel to
each other according to the third restriction manner while the contact is obtained
by the two surfaces intersecting with each other according to the forth restriction
manner. However, a further secure retention of the operating position of the bobbin
case 2 in the upward direction is obtained by the addition of the vertical direction
sub-support portion 43. In a case where the fourth restriction manner is selected
among the third and fourth restriction manners, the vertical direction sub-support
portion 43 serves as the guide portion instead of the vertical direction support portion
41.
[0061] According to the aforementioned first to fourth restriction manners, the bobbin case
removing and attaching mechanism 10 is obtained while the bobbin case 2 that is inserted
into the bobbin case accommodating portion 13 of the loop taker 1 is removable therefrom
in a state where the needle plate 5 is removed from the loop taker 1. In addition,
the bobbin case 2 is insertable into the predetermined operating position at the bobbin
case accommodating portion 13. Accordingly, the user easily inserts or attaches the
bobbin case 2 at the predetermined operating position in the loop taker 1 and removes
the bobbin case 2 from the loop taker 1. As a result, according to the bobbin case
removing and attaching mechanism 10 of the embodiment, a broken thread because of
a blocking of a path of the needle thread, and the like that occurs in a case where
the bobbin case 2 is dislocated from the predetermined operating position, may be
restrained to thereby achieve appropriate stitches.
[0062] During the sewing operation, a vibration is constantly generated so as to dislocate
the bobbin case 2 from the predetermined operating position. In addition, when the
sewing apparatus is carried or transferred, a force for dislocating the bobbin case
2 from the predetermined operating position may occur because of the vibration, and
the like. In a case where the aforementioned vibration or the force is generated,
the movement of the bobbin case 2 in the vertical direction is restricted, within
the size of the clearance through which the needle thread passes, because of the bottom
surface 6b of the bobbin case stopper piece 6, the vertical direction support portion
41 and the vertical direction sub-support portion 43 of the support portion 40 of
the bracket 4, and the race surface 11 of the loop taker 1. Thus, the bobbin case
2 is restrained to move so as to be positioned on the upper surface 12 from the race
surface 11 with which the bobbin case 2 is seated on, and the protruding portion 21
is restrained from forcibly engaging with an upper portion of the thread release portion
44.
[0063] Further, because of the restriction of the upward movement by the bobbin case stopper
piece 6 and the aforementioned first to fourth restriction manners, the bobbin case
2 that is inserted into the loop taker 1 is retained at the predetermined operating
position while the clearances through which the needle thread passes are secured.
Consequently, according to the bobbin case removing and attaching mechanism 10 of
the embodiment, a sewing malfunction such as the broken thread that may be caused
by the reduced clearance is restrained, thereby forming the appropriate stitches.
[0064] The insertion and attachment of the bobbin case 2 relative to the loop taker 1 is
obtained by removing the needle plate 5 from the bracket 4 in a state where the bracket
4 is fixed to the carrier plate 3. Thus, the removal and attachment of the bobbin
case 2 is easily performed, which may lead to an increase of operability.
[0065] Furthermore, the vertical direction support portion 41 and the rotation direction
support portion 42 are formed by a downward bending of a portion of the support portion
40 at the opening edge of the bracket 4. The thread release portion 44 is formed by
a block member that is fixed to the rear surface 4b of the bracket 4. The plane surface
portion 25, the reverse rotation stopper surface 24, and the protruding portion 21
are formed at the bobbin case 2 in such a manner to be contactable with the vertical
direction support portion 41, the rotation direction support portion 42, and the thread
release portion 44 respectively. In addition, the upper-right surface portion 37 is
formed at the bobbin case 2 so as to make contact with the bobbin case stopper piece
6 that is fixed to the needle plate 5. Accordingly, the configuration of the bobbin
case removing and attaching mechanism 10 is simplified to thereby achieve a cost reduction.
1. A bobbin case removing and attaching mechanism (10), comprising:
a loop taker (1) arranged within a work supporting bed for a sewing apparatus and
rotatable about an axis (Z) of the loop taker (1);
a bobbin case (2) inserted into an upwardly opening bobbin case accommodating portion
(13) formed in the loop taker (1);
a bracket (4) mounted on a fixing member (3) on the work supporting bed, the said
bracket (4) including an opening (45) through which the bobbin case (2) passes when
the bobbin case (2) is inserted into or removed from the bobbin case accommodating
portion (13); and
a needle plate (5) attached to an upper portion of the bracket (4) and closing at
least a portion of the opening (45) of the bracket (4), the needle plate (5) including
a bobbin case stopper piece (6) which restricts an upward movement of the bobbin case
(2) when the bobbin case is inserted into the bobbin case accommodating portion (13)
and arranged at an operating position thereof, wherein
when the needle plate (5) is attached to the bracket (4) with the bobbin case (2)
in the bobbin case accommodating portion (13), the bobbin case (2) is retained at
the operating position with movement of the bobbin case (2) being restricted by the
bracket (4) and the bobbin case stopper piece (6), and
when the needle plate (5) is removed from the bracket (4) and the bracket (4) remains
fixed to the fixing member (3), the bobbin case (2) may be removed from or attached
to the bobbin case accommodating portion (13).
2. A bobbin case removing and attaching mechanism (10) according to claim 1, wherein
the bracket (4) includes a rotation restricting portion (42, 44) restricting an insertion
direction of the bobbin case (2) and restricting a rotation of the bobbin case (2),
and a guide portion (41) making contact with a portion of an upper side surface of
the bobbin case (2) when the bobbin case (2) is inserted into the bobbin case accommodating
portion (13) and restricting an upward movement of the bobbin case (2), and wherein
clearances through each of which a needle thread passes are formed between the rotation
restricting portion (42, 44) and the bobbin case (2) and between the guide portion
(41) and the bobbin case (2) respectively.
3. A bobbin case removing and attaching mechanism (10) according to claim 2, wherein
the guide portion (41) is formed by a downward bending of a portion at an edge of
the opening (45) of the bracket (4).
4. A bobbin case removing and attaching mechanism (10) according to claim 1, wherein
the bobbin case stopper piece (6) includes elasticity to press the bobbin case (2).
5. A bobbin case removing and attaching mechanism (10) according to claim 4, wherein
the bobbin case stopper piece (6) is formed separately from the needle plate (5) and
is removably fixed to a lower surface (5b) of the needle plate (5).
6. A bobbin case removing and attaching mechanism (10) according to claim 5, wherein
the bobbin case stopper piece (6) is an elongated member made of metal and fixed to
the lower surface (5b) of the needle plate (5) in a cantilever manner.
7. A bobbin case removing and attaching mechanism (10) according to claim 4, wherein
the bobbin case stopper piece (6) is formed separately from the needle plate (5),
the bobbin case stopper piece (6) including a base portion fixed to the lower surface
(5b) of the needle plate (5) and a free end portion being apart from the lower surface
(5b) of the needle plate (5) by a predetermined distance.
8. A bobbin case removing and attaching mechanism (10) according to claim 7, wherein
the bobbin case stopper piece (6) is made of metal.