Field of Invention:
The invention is related to automated bag conversion machine, particularly,
stitched bag formation. The invention is about sewing thread lubrication apparatus
provided to lubricate the sewing thread prior to using it on a sewing machine.
5
Background of invention:
Fine powder form material such as cement, chemical powder or granular form
products like fertilizer, polymer or animal feedstuff is stored in sacks. There are
two types of sacks - block-bottom type and cushion type.
10
Cushion type sacks, which are easier to construct are also made from woven
fabric (coated or uncoated) made into of a tubular structure. On the automated bag
conversion machine used for manufacturing of cushion/pillow shape, high speed
stitching/sewing machine are used.
15
Generally, multifilament yarn is used as sewing thread for the formation of
cushion shape bags. Mostly people use both twisted or air intermingled yarn as
sewing thread, by ordering in bulk. It is also known that during usage of this yarn
on high speed sewing machine sometimes there is an unacceptably high number
20 of breakages of sewing thread. The strength of the seam itself is also found to be
reduced undesirably.
3
During further investigation it was revealed that main causes of yarn breakage
were splitting of filaments of the multifilament yarn which is attributed to the high
temperature generated on sewing needles because of the friction between the
threat and the needle. The splitting of filament in yarns is thus attributed generally
to drying of yarn or lack of lubrication. This consequently resulted 5 in generation
of higher friction leading to heat generation on stitching needle which ultimately
results in reduction of seam strength.
There is therefore a need to provide a method of and apparatus for lubricating the
10 sewing thread before it is passed through the sewing needle for the purpose of
sewing.
Objective and Advantages of Invention:
Accordingly, the main objective of invention is to provide an apparatus for
15 lubricating the sewing thread before it is passed through the sewing needle for the
purpose of sewing a fabric on a bag conversion line.
Another object of the invention is to provide a method of lubricating the sewing
thread before it is passed through the sewing needle for the purpose of sewing a
20 fabric on a bag conversion line.
Yet another objective of the invention is to provide a control system for the
lubrication application on stitching thread.
4
A further objective of the invention is to provide an apparatus for lubricating more
than one sewing thread simultaneously.
List of Figures:
Figure 1 shows a schematic block diagram/flowchart 5 of the device of the
invention
Figure 2 shows one view of the lubrication device of the invention
Figure 3 shows another view of the lubrication device of the invention
Figure 4 shows the soaking station
10
List of parts:
1. Sewing thread lubrication
15 apparatus
2. Sewing thread
2A. Individual filaments of
sewing thread
2B. Lubricated thread
20 3. Sewing thread supply
station
4. Lubricant station
5. Lubricant reservoir
5A. Lubricant
25 6. Pneumatic feeder
6A. Air solenoid
7. Soaking station
8. Manifold
9. Individual reels of sewing
30 thread
10. Support frame
10A. Interim support
10B. Sub-frame
10C. Soaking station mounter
35 11. Pressure regulator
12. Compressed air intake tube
13. Air compressor
14. First air passage tube
15. Second air passage tube
40 16. Air filter
17. Lubricant pool
18. Lubricant outlet tube
19. Cartridge
20. Individual lubricant carrier
45 tube
21. Lubricant release unit
22. Container
22A. Sewing thread inlet hole
22B. Lubricated thread outlet
50 hole
23. Lubricant soaker medium
24. Pressing device
25. Foundation Frame
55
5
Summary of Invention:
The invention discloses a sewing thread lubrication apparatus provided to
lubricate the sewing thread prior to using it on a sewing machine. It comprises a
sewing thread supply station (3) where reels of sewing thread (1) are positioned. It
also comprises a lubricant station (4) where lubricant 5 reservoir (5) and a
pneumatic feeder (6) are positioned. It finally comprises a soaking station (7)
where the sewing thread gets soaked in lubricant before being used for stitching.
The soaking station (7) has an arrangement where the at least one moving thread
(2) is preferably passed through a pool of lubricant. Passing the thread through the
10 pool (17) of lubricant (5A) allows the lubricant (5A) to enter into the structure of
the thread (2), thereby soaking it before leading it to the sewing machine. The
soaking station (7) is designed to take in multiple threads. A support frame (10) is
provided to support the various components of the invention.
15 Detail Description of Invention:
In a typical conventional bag conversion machine where a fabric is converted into
a storage bag, the sewing/stitching threads are directly fed to sewing machine
from a bobbin stand. The cut fabric is delivered to the sewing/stitching machine
positioned after a station for folding the fabric. The stitching machine makes
20 seams at the either end (top or bottom) of cut fabric using the supplied sewing
thread.
6
Depending upon the type of stitching used, the numbers of sewing threads are
determined.
Accordingly, the present invention provides a sewing thread lubrication apparatus
(1) (also termed as a yarn lubrication unit) for lubricating the 5 sewing thread (2) or
yarn. It comprises a sewing thread supply station (3) where reels of sewing thread
(1) are positioned. It also comprises a lubricant station (4) where lubricant
reservoir (5) and a pneumatic feeder (6) are positioned. It finally comprises a
soaking station (7) where the sewing thread gets soaked in lubricant before being
10 used for stitching.
The thread lubrication apparatus (1) is placed upstream of the sewing/stitching
machine.
15 According to device of the invention, the sewing thread (2) is made to pass
through the soaking station (7), which is a part of the sewing thread lubrication
apparatus (1) which is placed at an upstream location from the sewing/stitching
machine, as shown in block diagram shown in Figure 1. The lubricant (5A) from
the lubricant reservoir (5) (after optionally mixing it with air) is fed to the soaking
20 station (7) via a manifold (8) by the pneumatic feeder (6).
Figures 2 and 3 show two separate views of the lubrication apparatus (1) of the
invention.
7
The sewing thread station (3) may be a platform or a system of shelves where
individual reels (9) of sewing thread (2) are positioned. A framework of supports
is provided so that the sewing threads (2) are spatially configured for suitable
entry into the soaking station (7).
5
As discussed earlier, the lubricant station (4) comprises a lubricant reservoir (5)
and a pneumatic feeder (6). The pneumatic feeder in turn comprises an air
solenoid (6A) for controlling the flow of lubricant (5A) and a pressure regulator
(11) to control the pressure of the lubricant/air mixture and the pressure at which
10 the air is mixed with the lubricant (5A).
As shown in Figures 2 and 3, a lubricant reservoir (5) is mounted on a support
frame (10) (or simply a frame). On the frame (10) is also mounted the air solenoid
(6A) and the pressure regulator (11). An compressed air intake tube (12) leading
15 from an air compressor (13, not shown in figures) is connected to the pressure
regulator (11). A first air passage tube (14) is provided between the pressure
regulator (11) and the air solenoid (6A). A second air passage tube (15) is
provided between the air solenoid (6A) and the lubricant reservoir (5). The
pressure regulator (11) takes in air through the compressed air intake tube (12)
20 and sends it to the air solenoid (6A) at a controlled pressure. The air solenoid (6A)
further passes on the air through the second air passage tube (15) to the lubricant
reservoir (5). An air filter (16, not shown in figures) is optionally provided
8
through which the air from the air solenoid (6A) may pass before entering the
lubricant reservoir (5).
The sewing thread (2) is typically made of multiple filaments (2A – not shown in
figures), which are preferably intertwined. There exist gaps or 5 spaces between the
individual filaments (2A) of the thread. A lubricated thread should be such that
the lubricant not only coats the external or surface of the thread (2) but also
surrounds the individual filaments (2A). In other words, the thread (2) should get
soaked in the lubricant (5A). This is important because the thread (2) that is not
10 properly lubricated in this manner may still be prone to drying out before it
reaches the sewing needle or it may not have sufficient amount of lubricant
necessary to overcome the drawbacks stated earlier.
In its simplest form, the lubricating means is the soaking station (7) where the
15 sewing thread (2) gets soaked in lubricant (5A). The soaking station (7) is
mounted on the frame (10) by any means known to a person skilled in the art. In a
preferred embodiment, a soaking station mounter (10C), which is a simple
structural member such as a bar or an angle or similar, is used as shown in Figure
2, and attached to the frame (10) by conventional joining means such as welding
20 or bolting.
The soaking station (7) has an arrangement where the at least one moving thread
(2) is preferably passed through a pool (17, not shown in figures) of lubricant.
9
Passing the thread through the pool (17) of lubricant (5A) allows the lubricant
(5A) to enter into the structure of the thread (2), thereby soaking it.
In an embodiment of the invention, there could be any other means to soak the
5 thread.
As shown in Figures 2 and 3, the lubricant/air mixture is transported through at
least one lubricant outlet tube (18) to the manifold (8). In one aspect of the
invention air is optionally mixed with lubricant. For the purpose of further
10 discussion, the term lubricant implies lubricant coming out of the lubricant
reservoir which may or may not contain air.
The purpose of the manifold (8) is to receive the lubricant (5A) traveling through
the lubricant outlet tube (18) and redirect it into individual lubricant streams. The
15 individual lubricant streams are directed through a set of cartridges (19) from
which individual lubricant carrier tubes (20) emerge and which carry forward the
individual lubricant streams, which are still under some pressure. The individual
carrier tubes are led to the soaking station (7).
20 At least one thread, preferably more than one thread, is also made to travel into
the soaking station (7). In one aspect of the invention, for each said sewing thread
(2) there is provided an interim support (10A) at any point before its entry into
said soaking station (7). The interim supports (10A) may be supported by another
10
sub-frame (10B), which is in turn fixed to the support frame (10). The interim
supports (10A) are provided for the purpose that the threads do not get entangled
with any other parts of the apparatus or with other threads.
As shown in Figure 4, the soaking station (7) is designed to take in multiple
threads, release the lubricant (5A), soak the threads (2) with 5 lubricant (5A) and
forward the lubricated threads (2B) to the sewing machine. Accordingly, the
soaking station (7) comprises a lubricant release unit (21) corresponding to each
of the carrier tubes (2). It also comprises a container (22) which has a lubricant
soaker medium (23). The lubricant release unit (21) may be attached to the
10 container (22).
In one aspect of the invention the lubricant soaker medium (23) is a sponge or
structural foam. The lubricant (5A), when it emerges out of a lubricant release
unit (21), it comes out as a spray as it gets exposed to atmosphere. It's preferred
15 that the spray of the lubricant (5A) is in atomised form, however, it is not
necessary. It is, however, necessary that the spray or the outflow of the lubricant
(5A) from the release unit (21) is such that it soaks the lubricant soaker medium
(23) adequately with the lubricant (5A) .
20 In one aspect of the invention, there may be a single release unit (21) provided for
all individual carrier tubes (20) together or there may be a separate release unit
(21) provided for each individual carrier tube (20), or any combination thereof.
11
A pressing device (24) is provided that presses the lubricant soaker medium (23)
sufficiently so as to create the localised pool (17) of the lubricant at the top of the
lubricant soaker medium (23). The lubricant soaker medium preferably being a
sponge, a person skilled in the art will readily understand how the localised pool
(17) is formed under pressure. By the term 'soaking the 5 lubricant soaker
adequately' it is meant that the amount of lubricant (5A) emerging from all
release units collectively should be such that the lubricant soaker remains soaked
at all times so that under the pressure applied by the pressing device (24),
adequate pool of lubricant is formed at all times.
10
The pressing device (24) may be in the form of a bar of adequate self-weight, or a
bar that to which pressure is applied by external pressing means, or any other
form which applies pressure to the lubricant soaker medium (23).
15 In one aspect of the invention, the threads to be lubricated are passed through the
soaking station (7) such that they pass under the pressing bar and through the
localised pool (17) of the lubricant (5A). The pressure exerted by the pressing
device (24) and the speed of travelling thread is such that the thread has enough
time for soaking in the pool (17) of lubricant (5A) to get soaked adequately. A
20 person skilled in the art will know what values these parameters should be set as.
There should not be too much pressure such that the thread (2) gets trapped under
the pressure device. There should not be too little pressure so that the lubricant
12
pool (17) does not form. In general, by adequate soaking of the thread, it is meant
that the thread should not dry out before it reaches the sewing needle.
The lubricateded thread (2B) is led to the sewing machine.
5
Electro-Pneumatic equipment provided in the apparatus controls the rate of flow
of lubricant and time interval of spray or the lubricant output from a release unit.
In one aspect of the invention, the sewing thread passes through the spray or
10 lubricant output from a release unit directly before it passed under the pressure
bar.
Many thread/yarn lubricants have been found to be suitable. Water-based
lubricants for yarns may be used though it is preferable to use non-water-based
15 liquids. This is because the use of water in close proximity to sewing machine
parts and components may in some machines give rise to the introduction of rust
or tarnishing or alternatively may dissolve some of the conventional lubricant for
the machine itself thus reducing the effective working life of the sewing machine.
Alternative yarn lubricants are based on vegetable and mineral oils.
20
The provision of lubricant encourages the needle to slip round and between
adjacent yarns forming the fabric rather than cut into said yarns. Furthermore the
deep penetration of the lubricant forms a liquid surface on the surface of the yarns
13
of the fabric and this retards the build-up of heat due to the friction of the needle
and the sewing thread being passed through the fabric and thus reduces the
likelihood of thermoplastic yarns reaching a temperature at which they are
adversely affected.
5
It has been found that with experiments and using the process according to the
present invention that substantially higher speed for bag formation is possible.
It is evident from the foregoing disclosure that the invention has a number of
10 embodiments. These are described below.
1. A sewing thread lubrication apparatus (1) for soaking sewing thread (2) with
a lubricant (5A) comprising a sewing thread supply station (3) to supply at
least one sewing thread (2), a lubricant station (4), and a soaking station (7),
15 said lubrication apparatus (1) positioned upstream of a bag sewing machine,
characterised in that a lubricant (5A) from lubricant station is supplied to said
soaking station (7) and said at least one sewing thread (2) taken up from said
supply station (3) is soaked in the lubricant in said soaking station (7) before
feeding into the eye of a sewing needle of said sewing machine.
20 2. A sewing thread lubrication apparatus as disclosed in embodiment 1,
characterised in that said lubrication station (4) comprises a lubricant
reservoir (5) and a pneumatic feeder (6), wherein said pneumatic feeder (6) in
turn comprises a pressure regulator (11) and an air solenoid (6A), whereby
14
said pneumatic feeder (6) provides pneumatic pressure to the lubricant (5A)
in said reservoir (5).
3. A sewing thread lubrication apparatus as disclosed in any of embodiments 1
or 2, characterised in that said soaker station (7) comprises a container (22)
within which a lubricant soaker medium (23) is provided, 5 a pressure medium
to press said soaker medium (23) so that at least one lubricant pool (17) is
formed, through which said sewing thread (2) passes.
4. A sewing thread lubrication apparatus as disclosed in any of embodiments 2
to 3, characterised in that an compressed air intake tube (12) provides air to
10 said pressure regulator (11), a first air passage tube provides air under
pressure from said pressure regulator (11) to said air solenoid (6A), and said
air solenoid (6A) supplies a regulated quantity of air under pressure to said
reservoir (5).
5. A sewing thread lubrication apparatus (1) as disclosed in any of embodiments
15 2 to 5, characterised in that a lubricant outlet tube (18) leads lubricant under
pneumatic pressure from said reservoir (5) to a manifold (8).
6. A sewing thread lubrication apparatus (1) as disclosed in embodiment 6,
characterised in that said manifold (8) comprises a plurality of individual
cartridges (19), wherein there leads a corresponding lubricant carrier tube
20 from each of said cartridges (8) to carry lubricant (5A) to at least one
lubricant release unit (21) that is mounted on the container (22) of said
soaking station (7).
15
7. A sewing thread lubrication apparatus (1) as disclosed in any of embodiments
1 to 6, wherein at least one sewing thread receptor is provided on said
soaking station (7) through which said at least sewing thread (2) enters the
soaking station.
8. A sewing thread lubrication apparatus (1) as disclosed in 5 any of embodiments
6 to 7, characterised in that said lubricant release unit (21) is provided with at
least one opening (21A) through which said lubricant (5A) is released onto
said soaker medium (23).
9. A sewing thread lubrication apparatus (1) as disclosed in any of embodiments
10 2 to 9, characterised in that said reservoir (5), said pressure regulator (11),
and said air solenoid (6A) are securely mounted on a support frame (10), said
support frame (10) and said sewing thread supply station (3) being in turn
supported by a foundation frame (25).
10. A sewing thread lubrication apparatus (1) as disclosed in embodiment 9,
15 characterised in that for each said sewing thread (2) there is provided an
interim support (10A) at any point before its entry into said soaking station
(7).
11. A sewing thread lubrication apparatus (1) as disclosed in embodiment 10,
characterised in that thread intake openings (22A) and thread outlet openings
20 (22B) are provided in said soaking station (7) respectively to let in said thread
(2) for soaking in said lubricant (5A) and to let out the soaked thread (2B).
16
12. A sewing thread lubrication apparatus (1) as disclosed in any of embodiments
6 to 11, characterised in that the number of release units (21) may be greater
than 1.
13. A sewing thread lubrication apparatus (1) as disclosed in any of embodiments
9 to 12, characterised in that said soaking station (7) 5 is connected to said
frame (10) using a soaking station mounter (10C), said soaking station
mounter (10C) being a structural member.
14. A method of lubricating sewing thread, characterised in that said sewing
thread is lubricated before it enters into eye of the needle of a sewing machine
10 used in industrial bag sewing machines, said method comprising the steps of:
- providing an apparatus as claimed in any of claims 1 to 12
- supplying lubricant (5A) under pressure to said soaking station (7)
- forming a pool (17) of lubricant (5A) in the soaking station (7)
- passing the sewing thread (2) through said lubricant pool (17)
15 - taking the lubricated thread (2B) to said sewing machine.
While the above description contains much specificity, these should not be
construed as limitation in the scope of the invention, but rather as an
exemplification of the preferred embodiments thereof. It must be realized that
20 modifications and variations are possible based on the disclosure given above
without departing from the spirit and scope of the invention. Accordingly, the
scope of the invention should be determined not by the embodiments illustrated,
but by the appended claims and their legal equivalents.

We claim:
1. A sewing thread lubrication apparatus (1) for soaking sewing thread (2) with
a lubricant (5A) comprising a sewing thread supply station (3) to supply at
least one sewing thread (2), a lubricant station (4), and a soaking station (7),
said lubrication apparatus (1) positioned upstream of 5 a bag sewing machine,
characterised in that a lubricant (5A) from lubricant station is supplied to said
soaking station (7) and said at least one sewing thread (2) taken up from said
supply station (3) is soaked in the lubricant in said soaking station (7) before
feeding into the eye of a sewing needle of said sewing machine.
10
2. A sewing thread lubrication apparatus as claimed in claim 1, characterised in
that said lubrication station (4) comprises a lubricant reservoir (5) and a
pneumatic feeder (6), wherein said pneumatic feeder (6) in turn comprises a
pressure regulator (11) and an air solenoid (6A), whereby said pneumatic
15 feeder (6) provides pneumatic pressure to the lubricant (5A) in said reservoir
(5).
3. A sewing thread lubrication apparatus as claimed in any of the claims 1 or 2,
characterised in that said soaker station (7) comprises a container (22) within
20 which a lubricant soaker medium (23) is provided, a pressure medium to
press said soaker medium (23) so that at least one lubricant pool (17) is
formed, through which said sewing thread (2) passes.
18
4. A sewing thread lubrication apparatus as claimed in any of the claims 2 to 3,
characterised in that an compressed air intake tube (12) provides air to said
pressure regulator (11), a first air passage tube provides air under pressure
from said pressure regulator (11) to said air solenoid (6A), and said air
solenoid (6A) supplies a regulated quantity of air 5 under pressure to said
reservoir (5).
5. A sewing thread lubrication apparatus (1) as claimed in any of claims 2 to 5,
characterised in that a lubricant outlet tube (18) leads lubricant under
10 pneumatic pressure from said reservoir (5) to a manifold (8).
6. A sewing thread lubrication apparatus (1) as claimed in claim 6, characterised
in that said manifold (8) comprises a plurality of individual cartridges (19),
wherein there leads a corresponding lubricant carrier tube from each of said
15 cartridges (8) to carry lubricant (5A) to at least one lubricant release unit (21)
that is mounted on the container (22) of said soaking station (7).
7. A sewing thread lubrication apparatus (1) as claimed in any of claims 1 to 6,
wherein at least one sewing thread receptor is provided on said soaking
20 station (7) through which said at least sewing thread (2) enters the soaking
station.
8. A sewing thread lubrication apparatus (1) as claimed in any of claims 6 to 7,
characterised in that said lubricant release unit (21) is provided with at least
19
one opening (21A) through which said lubricant (5A) is released onto said
soaker medium (23).
9. A sewing thread lubrication apparatus (1) as claimed in any of claims 2 to 9,
characterised in that said reservoir (5), said pressure regulator 5 (11), and said
air solenoid (6A) are securely mounted on a support frame (10), said support
frame (10) and said sewing thread supply station (3) being in turn supported
by a foundation frame (25).
10 10. A sewing thread lubrication apparatus (1) as claimed in claim 9, characterised
in that for each said sewing thread (2) there is provided an interim support
(10A) at any point before its entry into said soaking station (7).
11. A sewing thread lubrication apparatus (1) as claimed in claim 10,
15 characterised in that thread intake openings (22A) and thread outlet openings
(22B) are provided in said soaking station (7) respectively to let in said thread
(2) for soaking in said lubricant (5A) and to let out the lubricated thread (2B).
12. A sewing thread lubrication apparatus (1) as claimed in any of claims 6 to 11,
20 characterised in that the number of release units (21) may be greater than 1.
13. A sewing thread lubrication apparatus (1) as claimed in any of claims 9 to 12,
characterised in that said soaking station (7) is connected to said frame (10)
using a soaking station mounter (10C), said soaking station mounter (10C)
25 being a structural member.
20
14. A method of lubricating sewing thread, characterised in that said sewing
thread is lubricated before it enters into eye of the needle of a sewing machine
used in industrial bag sewing machines, said method comprising the steps of:
- providing an apparatus as claimed in 5 any of claims 1 to 12
- supplying lubricant (5A) under pressure to said soaking station (7)
- forming a pool (17) of lubricant (5A) in the soaking station (7)
- passing the sewing thread (2) through said lubricant pool (17)
- taking the lubricated thread (2B) to said sewing machine.