Note: Descriptions are shown in the official language in which they were submitted.
This application is a division of
application Serial No. 474,645 filed February 19,
1985.
This invention relates to a thread loop
taker device of a zigzag sewing machine which may
produce many kinds of pattern stitchings.
An object of the present invention is to
make the loop hooking condition constant as possible
as could in the zigzag sewing machine, respectively of
the needle dropping positions, so that zigzag
stitchings of large width may be provided without
causing skipping or breaking the thread as con-
ventionally happening in the large wide zigzag
stitchings.
In accordance with the invention there is
provided a thread loop taker device for a zigzag
sewing machine having a vertically movable needle
which forms a thread loop thereunder. The device
includes a bobbin carrier and a rotatable race for
non-rotatably holding the bobbin carrier. Also
provided is a loop taker having an end portion shaped
as a beak and being rotatable -toge-ther with the race
and being rotatable relative to the race into a
plurality of posi-tions relative to the race. Drive
means rotate the end portion through at least one of
the positions in response to a change in the position
of the needle so that the end portion hooks the tread
loop. The drive means include a hollow shaft having a
first pin projecting perpendicularly therefrom, a
cylindrical shaft concentric to the hollow shaft and
having a second pin projecting perpendicularly there-
from, and a slide collar mounted concentric to the
hollow shaft and the cylindrical shaft and having an
oblong groove and an oblique groove cooperating with
the first pin and the second pin respec-tively.
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Further, in accordance with the invention,
there is provided a thread loop taker device for a
zigzag sewing machine which includes a needle variably
positioned by electronically stored data that
cooperates with the -thread loop taker so as -to produce
zigzag swi-tches. The loop taker device includes a
bobbin carrier and a rotational cylindrical member for
supporting -the bobbin carrier therein. Also provided
is a loop taker coaxial with and mounted outside the
cylindrical member for rotation therewith, the loop
taker having one end and an opposite end and also
having a beak extending from the one end and in a
direction of the rotation around a portion of the
cylindrical member for catching a thread loop formed
by the needle. A cam means engage the opposite end of
the loop taker for rotating the beak relative to the
cylindrical member. Means are provided for actuating
the loop taker, the means including a pulse motor
drivable in response to a change in the position of
the needle. Also provided are means for transmitting
the drive of the pulse motor to move the cam means so
that the beak rotates relative to the cylindrical
member in response to a change in the position of the
needle during rotation of the cylindrical member.
Fig. 1 is views showing crossings of a
needle and a beak of a loop taker in the prior art;
Figs. 2 and 3 are perspective views of the
present inventioni
Fig. 4 is a side view, partially in section,
of the present inven-tion;
Fig. 5 is a plan view, partially in section,
of the present invention;
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Figs. 6 and 7 are a second embodiment of the
present invention, and Fig. 6 is a side vieT~7,
partially in section, and Fig. 7 is a perspective view
of an element part thereof; and
Fig. 8 is a side view, partially in section,
of a third embodiment of the present invention.
In a conventional zigzag sewing machine, if
a needle dropping position is different as shown in
Fig. 1 as in a left basic line (L), a middle basic
line (M) and a right basic line (R), crossing
conditions between a needle 1 and a beak 2 of a loop
taker are differed respectively, differently from
straight stitching sewing machines. If a size of a
thread loop of the middle basic line (M) is made
proper, the crossing conditions are worst at the
remotest needle dropping positions of the left (L) and
the right (R). A loop of the upper thread is too
large in -the lef-t (L), and the loop is too small in
the right (R). Thus, the conditions are contrary each
other, and hooking of the thread loop is difficult in
each of the needle dropping positions to cause
skipping on breaking the -thread.
In order to improve such crossing
conditions, it was proposed to make -the vertical
movement of the needle slow when hooking the thread
loop, or make fast speed of rotational movement of the
loop taker for removing causes of skipping or breaking
the thread. Unfortunately, such ideas have not been
yet commercialized.
A thread loop taker device of a zigzag
sewing machine by the presen-t invention has removed
defects of the prior art, and devised so that it may
be also worked in electronic control sewing machines
and pattern cam control sewing machines which memorize
data of needle positions for stitching patterns.
3~ ~
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Explanations will be made to embodiments of
the invention.
In the attached drawings, a reference
numeral 3 designates a race of a full rotation type,
and it is arranged with a loop taker 15 having a sharp
beak 2 which is positioned at an appropriate place of
-the outer circumferential wall of a cylindrical shape
thereof, and is charged therein with a bobbin carrier
4 which is restrained in rotation and carries a
bobbin. Above the race 3 and the bobbin carrier 4, a
needle plate 6 is furnished, which is detachably
secured to a machine frame of a bed of a sewing
machine as seen in Fig. 2. The needle plate 6 is
defined with a needle drop hole 7 of a large width for
passing a needle 1 and openings 9 for raising and
dropping feed dogs 8.
The race 3 is secured integrally with a
hollow shaft 11 which is formed with a screw gear 10
on a rotation axial line (see Fig. 4). A numeral 12
designates a shaft which rotatably holds the race 3,
and the screw gear 10 is in mesh with a screw gear 14
firmly mounted on a drive shaft 13 and is driven by a
motor (not shown).
The beak 2 is formed at the end portion of a
perpendicular part bent upwardly of the loop taker 15
which is rotatably pivoted on the shaft 12 of the race
3. The loop taker 15 has a spring 19 at its
appropriate part, so that its other end attaches to
~ the side of a cam plate 18 mounted on a rotation shaft
17 of a driving element 16 such as a pulse motor which
is provided on the lower surface of the bottom of the
race 3.
The numeral 20 designates a non-conductive
cylindrical body which is secured on the hollow shaft
11 as one body with the race 3, and its outer cir-
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cumference is provided with a plurality of conductivemembers, each of which is connected to a maynetic
field coil and to a power source brush 21.
A second embodiment of the invention is
provided with a cylindrical shaft 22 at a fitting part
with the hollow shaft 11 of the loop taker 15, and is
implanted with a pin 23 projecting from the shaft 22
perpendicularly. The cylindrical shaft 22 is mounted,
on its outer circumference, with a slide collar 27.
The collar is formed with an oblique groove 24 for the
pin 23 in its half upper part as well as an oblong
groove 26 for a pin 25 projecting from the hollow
shaft 11 in its half lower part, thereby to move the
shaft 11 vertically, and is formed with a lateral
groove 28 for an end portion 31 of a fork lever 30
which is driven by a driving element 29 such as a
pulse motor positioned at an appropriate part of the
machine frame.
A third embodiment of the invention is shown
in Fig. 8. A shaft 32 supports the race 3, and is
driven by a driving element 33 such as a pulse motor
via gears 34, 35. The race 3 is provided with a gear
36 therewithin for meshing with a gear 37 on which a
cam plate 18 is provided coaxially, and the cam plate
18 is pressed by the loop taker 15 with its end
portion. The driving elements 29, 33 may be
substituted by cam members to be rotated.
The device of the invention is composed as
mentioned above. When the sewing machine is driven to
move the needle vertically and simultaneously the race
is rotated, needle amplitude data of pattern stitching
are taken out from a data memory and the needle is
moved laterally to produce patterns. At this time,
v~
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said needle amplitude data are input into the driving
element 16, 29 or 33 to be driven by angular amounts
required respectively.
The rota-tion of said driving elements alters
relative posi-tions in a rotating direction between the
loop taker 15 and the race 3 during rotation of the
race 3 in order to alter phases of the loop taker 15
via rotation of the cam plate 18 or movement of the
oblique groove 24, so that the beak 2 crosses with the
needle 1 at time when the needle 1 moves upwardly by
~M under the same condition as -the needle crossing in a
middle basic line (M), though in a left basic line (L)
and a right basic line (R).
With respect to the crossing condition of
the needle and the beak~ the loop taker is moved
forward or backward relatively with the race via the
driving element by the pattern stitching needle
amplitude data taken out from the data memory. The
beak 2 crosses with the needle by the same amount ~ of
the needle rising as the amount ~ M of the middle
basic line (M) even if it is in any position, and
therefore the thread loop may be exactly caught
without skipping or breaking the thread.
