Method of and apparatus for feeding fabric to a sewing machine

A method and apparatus for feeding a tubular fabric to a sewing portion of a sewing machine so as to set a hem on the edge portion of the fabric formed as a twice-folded, three-layered band. The operation is performed so that a left rear clamp is moved to the right so as to contact a holder extending from the sewing portion on its left side; the tubular fabric is inserted around the holder from the free end thereof; a main left front clamp is moved to the right and a right front clamp is moved to the left so as to clamp intermediate portions of the peripheral surface of said fabric from the outside. Then the left rear clamp is moved to the left and a main right rear clamp is moved to the right so as to stretch right and left sides of the fabric closer to the sewing portion from the inside to the outside, so that the right and left sides of the fabric become wider than the clamped portions of the fabric. Then the left rear clamp and main right rear clamp, while stretching the fabric, are moved toward the clamped portions of the fabric along the holder, so that the edge portion of the fabric forms a twice-folded, three-layered band.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a technique of feeding a piece of fabric 
formed as a tubular or a cylindrical shape to a sewing portion of a sewing 
machine as as to sew a hem portion of the fabric. 
2. Description of the Prior Art 
To perform the so-called lapped-edge stitching (see FIGS. 16A, 16B and 16C) 
using a hem-stitching sewing machine by means of a chain stitch, a fabric 
edge-lapping tool such as a twicefolding tool and a fabric edge detector 
have conventionally been provided at a position closer to the fabric 
feeding direction of the sewing portion of a sewing machine. The fabric 
edge-lapping tool is operated manually when inserting a piece of fabric so 
as to form a twice-folded, three-layered band 38, 39 (see FIGS. 16A, 16B 
and 16C) along one edge portion of the fabric. The fabric edge detector 
detects the edge of the fabric while feeding the fabric in such a way as 
to perform the so-called overlock stitching as the overcasting stitches 
accurately enwrap the thickness of the folded fabric portion and the 
outermost fabric end, and moves horizontally by intersecting at right 
angles the feeding direction of the fabric. 
Accordingly, the fabric edge-lapping tool and the fabric edge detector do 
not serve as obstacles in the case of a flat-shaped piece of fabric. 
However, in the case of a cylindrically-shaped piece of fabric, and 
particularly when the diameter of the cylinder is small, for instance, the 
the case of the edge of a sleeve of a child's shirt, the fabric 
edge-lapping tool and the fabric edge detector serve as obstacles even if 
the sleeve is inserted around the cylindrically shaped bed of a so-called 
free arm sewing machine. It has been extremely difficult and practically 
impossible to feed the fabric and accurately perform overlock stiching 
while manually inserting the edge of fabric into the fabric edge-lapping 
tool and making the edge of the fabric three-layered. 
SUMMARY OF THE INVENTION 
Accordingly, an object of the invention is to remove the drawbacks of the 
prior art by providing a method of feeding a piece of fabric to a sewing 
machine and an apparatus therefor which, even if the fabric has a very 
small diameter, will render the conventional fabric edge-lapping tool 
unnecessary, eliminate manual handling of the fabric which has hitherto 
required skilled art, and is capable of feeding the edge of the fabric by 
accurately and mechanically folding the same, by feeding the edge of the 
fabric to the sewing portion of an overcasing sewing machine after making 
the edge portion of a cylindrically shaped fabric into a three-layered 
band in advance, and which will permit a smooth feeding of the fabric 
without the fabric edge detector serving as an obstacle and will enable 
the provision of an accurate lapped-edge stitching using the overcasting 
sewing machine so as to make it possible to cope with a change in the 
diameter of a cylindrically shaped fabric. 
According to the present invention, a method for sewing a hem of a 
cylindrical fabric to a sewing machine is characterized by comprising the 
steps of: sewing one edge of a piece of flat-shaped fabric with the other 
edge thereof so as to make the fabric into a cylindrical shape; inserting 
the cylindrical fabric around a cylindrical holder extending from a sewing 
portion of the sewing machine so as to support the fabric around the 
holder; clamping right and left intermediate portions of the peripheral 
surface of the fabric onto the holder from the outside; stretching right 
and left portions of the fabric closer to the sewing portion from the 
inside toward the outside so that the right and left portions are expanded 
in the right and left directions slightly more than the clamped portions 
of the fabric; moving the stretched portions of the fabric toward the 
clamping intermediate portions of the fabric until the stretched portions 
are disposed over the clamped portions, so that the fabric is folded twice 
and the edge of the fabric on the outermost side slightly projects from 
the edge of an inner folded, clamped portion of the fabric; pressing the 
folded portion of the fabric from the outside; moving the pressed portion 
of the fabric in the pressed state backwardly to the sewing portion in 
parallel with the holder; and releasing the pressing and clamping of the 
folded portion of the fabric. 
In a sewing machine having a sewing portion including: a needle for holding 
an upper thread and moving vertically, a thread catching device which is 
located underneath the needle and operates in such a manner so as to catch 
the upper thread loop and form a seam, a presser foot for resiliently 
pressing a piece of fabric, and a feed gear which is located underneath 
the presser foot and operates in such a manner as to feed the fabric in 
cooperation with the presser foot, an apparatus for feeding a tubuler 
fabric into the sewing machine according to the present invention which 
consists of a holder extending horizontally in a cylindrical shape from 
the sewing portion of the sewing machine and having a free end from which 
a cylindrical fabric is inserted; a left rear clamp located to the left of 
the holder, the left rear clamp being movable right and left so that the 
left rear clamp is brought into contact with the holder on its left side, 
and movable back and forth in parallel with the holder; a main left front 
clamp located to the left of the holder, the main left front clamp being 
movable right and left so that the main left front clamp is brought into 
contact with the holder on its left side, and movable back and forth in 
parallel with the holder; an auxiliary left front clamp opposed to the 
main left front clamp, the auxiliary left front clamp being movable right 
and left so that the auxiliary left front clamp is brought into contact 
with the main left front clamp on its left side, and movable back and 
forth together with the main left front clamp; a main right rear clamp 
located normally to the left of the holder, the main right rear clamp 
being movable right and left across the holder and movable back and forth 
in parallel with the holder; an auxiliary right rear clamp opposed to the 
main right rear clamp, the auxiliary right rear clamp being movable right 
and left so that the auxiliary right rear clamp is brought into contact 
with the main right rear clamp on its right side and movable back and 
forth together with the main right rear clamp; a right front clamp located 
to the right of the holder, the right front clamp being movable right and 
left so that the right front clamp is brought into contact with the holder 
on its right side and movable back and forth in parallel with the holder.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Description of an embodiment of the present invention of the application 
will be made hereinunder with particular reference to FIGS. 1 to 16. In 
the specification, the term "right" is defined to be right on FIGS. 1 and 
2 and "left" to be left on FIGS. 1 and 2, and the term "forward" is 
defined to be downward on FIG. 1 and "backward" to be upward on FIG. 1. 
The sewing machine has a sewing portion with the following arrangement. An 
arm 1 of the sewing machine supports: a needle 2 for supporting an upper 
thread and movable vertically; and a presser foot 4 for pressing a fabric 
3 by means of a resilient force. A bed 5 of the sewing machine supports 
the following: a looper 6 which is situated immediately below the needle 2 
and moves back and forth in such a way that a loop seam for an edge of the 
fabric is formed in cooperation with the needle 2 by catching an upper 
thread loop created by the needle 2 through friction as the needle 2 rises 
after penetrating the fabric; and a feeding gear which is situated below 
the presser foot 4 and operates by appearing and disappearing from the bed 
5 in such a way as to feed the fabric 3 linearly to the left on the bed 5 
in cooperation with the presser foot 4. 
The bed 5 integrally forms a support 8 extending horizontally in a 
cylindrical shape from the sewing portion of the sewing machine forwardly 
toward the operator. A supporting base plate 9 distanced to the right from 
the arm 1 and the bed 5 supports an extending body 10 which is situated to 
the right of the support 8 in parallel with and at the same height as the 
support 8 and extends horizontally in a bar shape from its backward 
position opposite to the sewing portion toward the operator. The base 
plate 9 forms a support for inserting and holding the fabric 3 together 
with the support 8. 
A base plate 11 secured at a distance to the left from the arm 1 and the 
bed 5 supports: a left rear clamp 12 normally situated to the left of the 
support 8 and closer to the operator forwardly from the sewing portion; 
and a cylinder 13 which is connected to the left end of the left rear 
clamp 12 and is operated by the supply of a pressure fluid so that the 
left rear clamp 12 moves right and left and comes into contact with the 
left side of the support 8. A cylinder 34 may preferably be interlinked 
with the left rear clamp 12 so as to cause the left rear clamp 12 to move 
away to the left. The base plate 11 further supports a cylinder 14 which 
is operated by the supply of a pressure fluid and is connected to the left 
rear clamp 12 and the cylinders 13, 34 so that they move back and forth in 
parallel with the support 8. 
The base plate 11 also supports: a main left front clamp 15 located to the 
left of the support 8 and at a position closer to the operator than the 
left rear clamp 12 or forwardly of the left rear clamp 12; and a cylinder 
16 which is connected to the left side of the main left front clamp 15 and 
operates by the supply of a pressure fluid. The main left front clamp 15 
is interlinked wth the cylinder 16 so that it comes into contact with the 
left side of the support 8 by the cylinder 16. Also, a cylinder 35 for 
moving the main left front clamp 15 away to the left is interlinked with 
the main left front clamp 15. 
The main left front clamp 15 supports: an auxiliary left front clamp 17 
opposed to the main left front clamp 15 in the longitudinal (back and 
forth) and transverse (right and left) directions; and a cylinder 18 which 
is conected to the left side of the auxiliary left front clamp 17 and is 
operated by the supply of a pressure fluid so as to move the auxiliary 
left front clamp 17 to right and left in such a manner as to come into 
contact with the left side of the main left front clamp 15 and move away 
from the same. 
The base plate 11 also supports a cylinder 19 which is operated by the 
supply of a pressure fluid so as to drive the main and auxiliary left 
front clamps 15, 17 and the cylinders 18, 35 back and forth in parallel 
with the support 8. 
The base plate 9 supports: a main right rear clamp 20 normally located 
slightly to the left of the extending body 10 and at a position closer to 
the operator than the sewing portion; and a cylinder 21 which is connected 
to the right side of the main right rear clamp 20 and operated by the 
supply of a pressure fluid. The main right rear clamp 20 is moved by the 
cylinder 21 from the left of the extending body away to the right of the 
same. 
The main right rear clamp 20 supports: an auxiliary right rear clamp 22 
opposed to the main right rear clamp 20 in the longitudinal (back and 
forth) and transverse (right and left) directions; and a cylinder 23 which 
is connected to the right side of the auxiliary right rear clamp 22 and is 
operated by the supply of a pressure fluid. The auxiliary right rear clamp 
22 is interlinked by the cylinder 23 with the main right rear clamp 20 so 
that the former comes into contact with the right side of the latter and 
departs from the same. 
The base plate 9 supports a cylinder 24 which is operated by the supply of 
a pressure fluid so as to move the main and auxiliary right rear clamps 
20, 22 and the cylinder 23 back and forth in parallel with the extending 
body 10. 
The base plate 9 also supports: a right front clamp 25 located normally to 
the right of the extending body 10 and at a position closer to the 
operator than the main and auxiliary right rear clamps 20, 22 or forwardly 
of the right rear clamps; and a cylinder 26 which is connected to the 
right side of the right front clamp 25 and is operated by the supply of a 
pressure fluid so that the right front clamp 25 comes into contact with 
the right side of the extending body 10. Further, a cylinder 36 is 
interlocked with the right front clamp 25 so that the later departs to the 
right of the extending body 10. Further, the base plate 9 supports a 
cylinder 27 which is operated by the supply of a pressure fluid so that 
the right front clamp 25 and the cylinders 26, 36 move back and forth in 
parallel with the extending body 10. 
On a table 28 to which the sewing machine arm 1 and the bed 5 are secured, 
the base plate 11 is secured to the left of the sewing machine, and a base 
29 to the right thereof as shown in FIG. 2. The base plate 9 is supported 
movably back and forth on the base 29. The base plate 9 is moved back and 
forth by means of the operation of a cylinder 33 located between the base 
plate 9 and the base 29. The base plate 9 supports a base plate 37 movably 
to right and left (see FIG. 4). A servo motor 30 secured to the base plate 
9 supports the right side of a screw 31 with its left portion screwed into 
the base plate 37, The screw 31 is rotated forwardly or reversely by the 
forward or reverse rotation of the motor 30. The three right-hand clamps 
20, 22 and 25 supported on said base plate 37 as well as the six cylinders 
21, 23, 24, 26, 27, and 36 are caused to move to right and left together 
with the base plate 37 by the motor 30. 
Also, a cylinder 32 is secured onto the base plate 11 so as to interlink 
said cylinder 32 and the presser foot 4 so that the latter is vertically 
movable by the supply of a pressure fluid to the cylinder 32. 
Preprogrammed output signals of a microcomputer are coupled with each 
cylinder on both sides so as to cause each clamp at the right and left 
positions and the presser foot to operate as described in the following 
section, or are coupled with a combination of timers, thereby to supply or 
discharge air or a liquid. 
The embodiment according to the present invention of the application has 
the aforementioned arrangement. An explanation of the operation is 
described as follows below with particular reference to FIGS. 5 to 15: 
a. As shown in FIG. 5, the left rear clamp 12 is caused to come into 
contact with the left side of the support 8 by the operation of the 
cylinder 13. The main and auxiliary left front clamps 15, 17 are moved 
away to the left of the support 8. 
The right front clamp 25 is moved away from the extending body 20 to the 
right by the operation of the cylinder 26. The main right rear clamp 20 is 
positioned at the left side of the extending body 10, or more 
specifically, at a position not protruding or distanced to the right from 
the extending body 10, while the auxiliary right rear clamp 22 is 
distanced from the extending body 10 to its right. 
b. As shown in FIG. 6, the inner surface of the fabric 3 which has been 
made in advance into a cylindrical shape by sewing both linear edges of a 
flat piece of fabric, is inserted around the peripheral surfaces of the 
support 8 and the extending body 10 from the forward or operator's side 
toward the backward direction with the surface which will become the upper 
face of the apparel facing outward. The inner surface of the fabric 3 is 
caused to cover the forward portions of the left rear clamp 12 and the 
main right rear clamp 20 facing the operator, and is supported by the 
same. 
c. A shown in FIG. 7, the main and auxiliary left front clamps 15, 17 are 
moved to the intermediate positions of the left side of the support 8 by 
the cylinder 19, and the right front clamp 25 is moved to the intermediate 
position of the right side of the extending body 10 by the cylinder 27. 
d. As shown in FIG. 8, the main left front clamp 15 is moved by the 
cylinder 16 to its right and comes into contact with the left side of the 
support 8. The right front clamp 25 is moved by the cylinder 26 to its 
left and comes into contact with the right side of the extending body 10. 
As a result, the fabric 3 is supported and clamped from outside by the 
clamps 15 and 25. 
e. As shown in FIG. 9, the left rear clamp 12 is moved slightly toward the 
left from the support 8 by the operation of the cylinder 34. The main 
right rear clamp 20 is also moved slightly toward the right from the 
extending body 10 by the operation of the cylinder 21. The auxiliary right 
rear clamp 22 clamps the fabric 3 in cooperation with the main right rear 
clamp 20 by moving toward the left by the operation of the cylinder 23. 
The edge of the cylinder fabric 3 is therefore stretched from its inner 
surface to the outward direction. 
f. As shown in FIG. 10, the left rear clamp 12 and the main and auxiliary 
right rear clamps 20, 22 are moved forwardly by the operation of the 
cylinders 14 and 24, respectively, while maintaining the fabric 3 being 
stretched, and come into an overlapping position with the outer side of 
the main left front clamp 15 and the right front clamp 25, respectively. 
As a result, the fabric is folded twice in a multi-layer. The edge of the 
fabric on the outermost side may preferably slightly project from the edge 
of a folded portion of the fabric on the inner side thereof. 
g. As shown in FIG. 11, the left rear clamp 12 is pulled out from the 
folded portion of the fabric 3 and moved backwardly by the operation of 
the cylinder 14. The main left front clamp 15 is moved slightly toward the 
left from the support 8 by the operation of the cylinder 35. The auxiliary 
left front clamp 17 is moved to the right by the operation of the cylinder 
18, so as to press the folded portion of the fabric against the main left 
front clamp 15. 
h. As shown in FIG. 12, the left rear clamp 12 is moved toward the left 
from the support 8 by the operation of the cylinder 34. The main and 
auxiliary right rear clamps 20, 22 together with the extending body 10 are 
moved backwardly to the sewing portion of the sewing machine in parallel 
with the support 8 by the operation of the cylinder 33, while the folded 
portions of the fabric 3 are pressed by the clamps in such a manner that 
the base plate 9 supporting the right rear clamps 20, 22 and extending 
body 10 is pulled backwardly by the cylinder 33 on the base 9. At the same 
time, the main and auxiliary left front clamps 15, 17 are also moved 
backwardly to the sewing portion of the sewing machine in parallel with 
the support 8 by the operation of the cylinder 19. The right front clamp 
25 is also moved backwardly by the operation of the cylinder 27. 
i. As shown in FIG. 13, the auxiliry left front clamp 17 is moved and 
separated from the main left front clamp 15 to the left by the operation 
of the cylinder 18. Then the main and auxiliary left front clamps 15, 17 
and the right front clamp 25 are pulled out from the folded portion of the 
fabric 3 by the operation of the cylinders 19 and 27, respectively, so as 
to release the clamping and pressing at the left side of the folded 
portion of the fabric. Then the presser foot 4 is lowered to the folded 
portion of the fabric by the operation of the cylinder 32. 
j. As shown in FIG. 14, the main and auxiliary left front clamps 15, 17 and 
the right front clamp 25 are moved and separated to the right and left 
sides of the support 8 and the extending body 10 by the operation of the 
cylinders 16, 18, and 36, respectively. 
k. As shown in FIG. 15, the main right rear clamp 20 is moved and separated 
to the left side of the extending body 10 by the operation of the cylinder 
21. The auxiliary right rear clamp 22 is separated to the right from the 
outside of the folded portion of the fabric 3 by the operation of the 
cylinder 23. The main and auxiliary left front clamps 15, 17 are moved 
backwardly toward the sewing portion of the sewing machine in parallel 
with the right and left sides of the support 8 and the extending body by 
the operation of the cylinders 19, 27, respectively. The outermost edge of 
the fabric 3 in this state is twice-folded as shown in FIG. 6A. 
l. The sewing machine is then started, the needle 2 for holding an upper 
thread is moved vertically, and the fabric 3 is fed to the left with its 
shape being a cylindrical shape by operating the thread-catching device 6 
and the feed gear 7. While the fabric 3 is being fed, the needle 2 is 
lowered through the thickness of the inner folded, two-layered portion 39 
of the fabric 3, from the above and slightly leftwardly inner side of the 
outermost edge 38 of the three-layered portion of the fabric 3, as shown 
in FIG. 16B. At the outermost edge of the three-layered portion of the 
fabric 3 is formed a hem-stitch seam, while at the folded, two-layered 
portion 39 is formed a concealed seam 40. When the sewing machine is 
stopped after the entire periphery of the cylinder of the fabric 3 has 
been sewn, the needle 2 and the pressure foot 4 are raised from the fabric 
3 and held in their raised position, the fabric 3 is moved toward the 
operator and is removed from the support 8 and the extending body 10. 
Subsequently, the outer two layers 38, 39 of the cylinder of the fabric 3 
are turned over to the right with the seam 40 as a fulcrum so as to serve 
as the edge of a sleeve of apparel as shown in FIG. 6C. 
m. When there is a change to the diameter of the cylinder of the fabric 3, 
the motor 30 is rotated in one direction so as to cause the base plate 37 
to move to right and left, as viewed in FIG. 1, on the base 9 via the 
screw 31. This, in turn, causes the extending body 10, the main and 
auxiliary right and left clamps 20, 22, and the right front clamp 25 to 
move right and left in interlinked relation with the six cylinders, 
thereby adjusting the interval with the support 8. When it is confirmed 
that the relative position of the extending body 10 and the clamps have 
been adjusted to fit the diameter of the cylindrical fabric 3, the motor 
30 can be stopped. 
Since the apparatus according to the present invention has the 
aforementioned arrangement and operates as stated above, the apparatus has 
the following effects. 
According to the present invention, after the fabric 3 is formed into a 
tubular or cylindrical shape it is fed to the sewing portion of the 
hem-stitching sewing machine, advancing mechanically and automatically 
into twice-folded, three-layered portions 38, 39, even if the fabric 3 is, 
for instance, a sleeve of a child's shirt having an extremely small 
diameter. It is unnecessary to use a fabric end-lapping tool and manual 
handling of the fabric for sewing the fabric while feeding the folded 
fabric to the sewing portion of the machine. It is unnecessary to have a 
skilled artisan to use a lapping tool and to do the manual handling. It is 
possible according to the present invention to effect the smooth feeding 
of the fabric without an obstacle being caused by a fabric edge detector 
for detecting the edge of the fabric in response to the needle of the 
sewing portion. It is also possible to adjust the apparatus in response to 
a change in the diameter of cylindrical fabric. 
To change the widthwise dimension in the back and forward direction of the 
twice-folded, three-layered portions 38, 39 of the fabric 3, it is 
possible to effect the change by changing the dimension and moving 
distance of each clamp in the back and forward direction thereof. Also, it 
is possible to operate each cylinder electromagnetically. Furthermore, it 
is possible not only to use a hem-stitching sewing machine by means of a 
chain stitch but also a regular sewing machine by means of a chain stitch 
by folding the edge of the fabric once or twice.