IL169665A - Sewing machines - Google Patents

Description

Improvements in sewing machines Yair Eilam The present invention relates to chain stitch sewing machines with the capability of locking several stitches along the chain seam wherever necessary and also of locking several stitches at the beginning or the end of the chain stitch seam.

More particularly, the invention provides a chain stitch sewing machine with a locking stitch mechanism that prevents the unraveling of the seam.

The present invention relates to one- or two-thread chain stitch machines as well as to overlock and interlock machines with or without a safe stitch mechanism, namely, a two- or more thread chain stitch formation mechanism, and also relates to one-needle or multi-needle chain stitch or overlock and interlock machines with or without a safe stitch.

For a long time, chain stitch machines have been widely used for a broad range of applications, typically for the clothing and garment industries as well as many others applications. The mechanism of chain stitch formation is well known in the prior art. The advantages of chain stitch machines over lock stitch machines lie mainly in their speed of operation and their seam flexibility. In addition, chain stitch machines do not suffer from the need for frequent stoppages in sewing operation in order to change the lower bobbin as do lock stitch machines.

However, the disadvantage of using chain stitch to join layers of fabrics in certain applications lies mainly in the possibility of the seam unraveling either at its end or when the thread snaps.

Reliable securing/locking techniques are required for chain stitch seams in order to overcome the current unraveling disadvantages.

Over the years, chain stitch machine manufacturers have attempted many types of solutions for the above-mentioned problem, but up to now, no chain stitch machine has had the capability of securing short sections (consisting of several stitches) anywhere along a seam at the touch of a button, thereby making it difficult for the chain-stitch seam to unravel.

Hitherto, in order to prevent the sewing thread of a chain stitch from unraveling at the sewing end, various methods have been known, including: (a) the use of several condensed stitches just before the sewing end; (b) making the sewing thread hard to unravel by altering the tension balance of the sewing thread at the sewing end; (c) leaving a small tail of sewn seam at the end of the seam in order to make it difficult for the sewing thread to unravel.

However, in the above conventional methods (a), (b) and (c) for preventing seams from unraveling, the sewing end is not safely secured.

The state of the art can be assessed by a review of the following recent Patents.

In Patent EP0897030, Douyasu Osamu discloses method and apparatus for preventing seam from raveling in double chain stitch sewing machine.

It is done by forming a double chain stitch near the sewing end point by collaboration of a plurality of needles and a looper. The looper thread is hooked and engaged on the hook at the left side of the needles. After driving the sewing machine for a half stitch or one stitch in this state, the looper thread hooked on the hook is cut off, captured and the end of the cut looper thread is pulled out from the final needle thread loop at the end of sewing. Therefore, raveling of thread from the sewing end point is prevented. This patent is referring only to option of securing the last stitch of the sewing seam.

In another Patent EP079292, Douyasu Osamu discloses another method and apparatus for preventing seam from raveling in double chain stitch sewing machine. It is done by using a plurality of needles moving vertically, a looper moving laterally from the right side of the plurality of needles for forming a double chain stitch by collaboration with the needles, looper thread engaging means for engaging with the looper thread consecutive to the looper from the cloth at a left side position from the needle drop point in the sewing machine bed when the looper advances leftward in the parallel direction of the needles, a first cutter for cutting off the looper thread engaged with the looper thread engaging means at the engaging portion, and a second cutter for cutting each one of the plurality of needle threads consecutive to the needles from the cloth through the looper and the looper thread consecutive to the looper from the cloth between the cloth and the looper. Therefore, raveling of thread from the sewing end point is prevented. Again this patent is referring only to option of securing the last stitch of the sewing seam.

Nolle Wolfgang disclosed a method of making the sewing thread hard to unravel by changing the tension balance of the sewing thread at the sewing end in a US Patent No. 5,381 ,745.

However this method of tension balance of the sewing thread at the sewing end does not prevent unraveling of the seam.

Japanese Laid-open Patent No. 6-233877 disclosed a method of disposing a looper thread hook slidably for holding the looper thread behind the looper of a double chain stitch sewing machine, and comprising the steps of stopping the operation of the sewing machine once immediately before the sewing end, holding the looper thread by the looper thread hook, resuming the operation of the sewing machine in this state to sew one stitch, and cutting both needle threads and looper thread after the sewing. Then, as the sewing operator removes the cloth from the sewing machine while holding the looper thread by the looper thread hook, the entangling state of the needle thread and looper thread is varied so that the sewing thread may be hard to ravel. This method also does not prevent unraveling and attempts to secure only the last stitch of the seam.

While some of the mechanisms seen in the prior art could be used in a chain stitch machine intended to prevent the unraveling of the seam, there appears to be no machine that fully relates to the requirements of locking several stitches produced by chain stitch machines wherever necessary along the sewn seam.

It is therefore one of the objects of the present invention to obviate the disadvantages of prior art machines and to provide a mechanism which is specifically configured to secure short sections (consisting typically of between 3 and 10 stitches) of a chain stitch seam anywhere along a seam, thereby making it difficult for the chain stitch to unravel.

It is a further object of the present invention to allow the locking of short sections (several stitches) at the end or the beginning of the chain stitch seam.

It is a further object of the present invention to allow a one-thread chain stitch seam to have the characteristics of a lock stitch seam, in the locked stitches.

It is a further object of the present invention to allow the interlocking of the upper thread and the additional securing thread in a two-thread chain stitch seam in the locked stitches, as will be explained later on, and by so doing, also causing the under thread in the locked stitches to be secured.

It is a further object of the present invention to allow the locking of short sections (several stitches) of a chain stitch seam anywhere along a seam and to perform the locking at high speed, higher than the speed of an average conventional lock stitch sewing machine.

Other objects and advantages of the invention will become apparent as the description proceeds.

No novelty is claimed here regarding the chain stitch formation mechanism or the threads used, which can be of any type used in garments, sportswear, etc.

The present invention provides a sewing thread insertion mechanism that is capable, when integrated into a conventional chain stitch sewing machine that is modified to accept it, of locking several consecutive stitches along the seam wherever necessary and also of locking several stitches at the beginning or the end of the seam without actually lowering the speed of the chain stitch machine. The locking will preferably be done when sewing in a straight line or along a mild curve, as is usually the case when stitching at the beginning and the end of the seam. In most cases, there are places on a long seam where several consecutive stitches can be locked in a straight line or a mild curve.

The locking procedure is performed by interlocking an additional securing thread with the conventional upper thread of the chain stitch, beneath the fabrics. It can be done at a high speed only for short sections of the seam (several consecutive stitches). For every locking cycle of several stitches, the amount of securing thread used for that operation is approximately 5 cm. (For the purpose of locking a larger amount of stitches, a regular lock stitch machine is required with an under-bobbin.) More specifically, the additional securing thread is threaded into the under-loops formed beneath the fabrics by the chain stitch upper thread during the normal formation of the chain stitches. It is inserted into the stitch under loop by a looper threaded with the securing thread. This looper inserts the securing thread into the first desired stitch to be locked, maintains its position in relation to the moving fabrics, and when the next consecutive stitch to be locked is formed, the looper resumes its movement and penetrates the next under-loop without releasing the previous locked stitch. The locking cycle continues until all the desired stitches are locked. At that time, an additional gripper element with a catcher and a cutter grabs the securing thread from the looper, holds it in position, thereby forcing the securing thread to remain in all the securing under-loops while the looper retreats to it starting position. While or immediately after the looper retreats, the cutter cuts and releases one part of the securing thread. The other part remains threaded in the looper and moves backwards with the looper, away from the several locked stitches, as a result of either the retreating of the looper or the sewing operator pulling the sewn fabrics from the sewing machine.

In a preferred embodiment of the present invention, there is provided a sewing thread insertion mechanism wherein the inserting mechanism comprises a looper with a hole close to its tip, which can be threaded with an additional securing thread, and a gripper element and a catcher and a cutter, said looper is situated perpendicular to the sewing machine needle on its left side, its tip and hole pointed towards that needle, said looper is parallel to the needle feed dog, and is capable of moving under the fabrics and in close proximity to the needle of the sewing machine once the needle penetrates the fabrics, said looper is capable of moving forwards in order to penetrate the under-loop created by the upper thread beneath the fabric during the locking cycles, and synchronically and with the same distance and direction as the movement of the fabrics so it will remain in the same position relative to the fabrics and the under-loop that is formed, in order to lock the determined number of consecutive stitches, as well as retreating backwards to its original position once the locking cycles are finished, and remains there until the next locking cycle begins, said gripper element and catcher are capable of grasping and holding the end of the securing thread in close proximity to the looper hole, before said looper starts to retreats to its original place threaded with the other part of the securing thread, said cutter is capable of cutting the securing thread while or immediately after said looper retreats to its original place.

Yet further embodiments of the invention will be described hereinafter.

As will become evident by looking at the diagrams herein, the described forward and backward movements of the looper, threaded with the additional securing thread, the operations of the gripper element and the catcher and the cutter, are all done during and in full synchronization with the chain stitch formation mechanism.

In the present invention, as will become evident by looking at the diagrams herein, the conventional chain stitch formation mechanism is hardly changed. Only minute modifications are required and they can be done by those skilled in the art.

The novelty of the present mechanism lies in the actions carried out by the various loopers, catchers, grippers and cutters, in the required manner, and not in the mechanisms needed to drive these tools, or in the tensioning, feeding and pulling mechanisms of the threads. For this reason the drive mechanisms, or the tensioning, feeding and pulling mechanisms of the threads, which can be prior art, are not detailed in the present specification.

The invention will now be described further with reference to the accompanying drawings, which represent by example preferred embodiments of the invention. Structural details are shown only as far as necessary for a fundamental understanding thereof. The described examples, together with the drawings, will make apparent to those skilled in the art how further forms of the invention may be realized.

In the drawings: FIG. 1 is a diagrammatic side view of a preferred embodiment of the thread inserting mechanism integrated in a two-thread chain stitch mechanism according to the invention; FIG. 2 to FIG. 12 are diagrammatic descriptions of the formation of locked stitches in a one-thread chain stitch machine according to the invention; FIG. 13 to FIG. 25 are diagrammatic descriptions of the formation of secured stitches in a two-thread chain stitch machine according to the invention; FIG. 26 is a diagrammatic view of the locked one-thread chain stitch according to the invention; and FIG. 27 is a diagrammatic view of the locked two-thread chain stitch according to the invention; There is seen in FIG. 1 parts of a conventional two-thread chain stitch sewing machine having a needle 10 and upper thread 1 1 with the spoo vrjf the upper a looper 30 threaded with the lower thread 31 having its spool 45, and the feed dog 46, arrow 23 showing the direction of movement of the fabric, and also there is seen in FIG. 1 the parts of the sewing thread inserting mechanism having a looper 14 threaded with the securing thread 1 5 that is fed out of a spool 16, and a gripper element which has also a catching thread capability 25a and a thread cutter 25b.

In the following figures, for reasons of convenience, the gripper element and the catcher 25a, and the cutter 25b, will be called 25.

The looper 14 has a hole 19 close to its tip, that can be threaded with the securing thread 15. The looper 14 is situated perpendicular to the needle 10 from its left side, having the tip and the hole pointing towards the needle 10. Looper 14 is parallel to the feed dog 46, and is capable of moving under the fabrics and in close proximity to the fabrics and to the needle 10 once the needle 10 penetrates the fabrics. Looper 14 is capable of moving forwards in order to penetrate the under-loop 32, as will be evident from examination of FIG. 14, made by the thread 1 1 under the fabrics during the locking cycles. Looper 14 is also capable of moving synchronically and with the same distance and direction as the movement of the fabrics, so it remains in the same position relative to the fabrics and the under-loop 32 that is being formed in order to lock the determined number of consecutive stitches. Typically number is 3 to 10 consecutive locked stitches. Looper 14 is also capable of retreating to its original position once the locking cycles have finished, and of remaining there until the next locking cycle begins.

The gripper element, which is also a catcher 25a, and the cutter 25b are capable of grasping, holding and cutting the end of the securing thread 15 in close proximity to the hole 1 , while or immediately after the looper 14 retreats to its original place, threaded with the other end of the securing thread 15, as will be explained in more detail in the following figures.

With reference to the rest of the figures, similar reference numerals have been used to identify similar parts.

In operation, the mechanisms are configured to function as follows: FIG. 2 to FIG. 12 are diagrammatic descriptions of the formation procedure of locked stitches in a one-thread chain stitch machine according to the invention; As illustrated in FIG.2, the needle 10 descends to below the fabric with the upper thread 1 1 , a hook 12 with an upward sloping section 18 begins to form a loop of chain stitch (as in current technology). Looper 14 threaded with the securing thread 15 is in its starting position.

As seen in FIG. 3, when looper 12 moves forward towards the needle 10, loop 20 (of thread 1 1 below the fabric) is formed. Upward sloping section 18 on looper 12 does not yet touch and penetrate loop 20.

As seen in FIG. 4, looper 14 moves and penetrates loop 20 and inserts the locking thread 15. The leading edge 22 of the looper 12 forces the loop 20 into a shape that enables looper 14 to penetrate. Looper 14 slides between the fabric and above looper 12 and passes alongside the needle 10. The end of Looper 14 with thread 15 remains inside the loop 20 (it does not pass through it). The distance between the tip of looper 14 that is close to the hole 19 and needle 10 is approximately half of a stitch length. The needle 10 begins its upward movement.

As seen in FIG. 5, after the needle 10 ascends, the fabric advances. Looper 14 maintains its position relative to the fabric (both movements are identical and synchronized). Looper 14 maintains its position inside Loop 20.

Clarification: Thread 15 is threaded into Looper 14 and has a free end that is about 5 cm long (from the looper hole to its point).

As seen in FIG. 6, after the fabric stops moving, looper 12 moves forward until its upward sloping section 18 touches and pushes the upper side of loop 20 a little. This enables needle 10 to descend into loop 20, which was formed by thread 1 1 under the fabrics. Looper 14 does not move from its place, and maintains its position relative to the fabric, as described in the diagram.

As seen in FIG. 7, after the needle 10 descends, looper 12 moves around the needle (as in conventional chain stitch machines). Looper 14 remains in position without moving.

As seen in FIG. 8, looper 12 penetrates and forms loop 21. The upward sloping section 18 touches and moves the upper side of loop 21.

As seen in FIG. 9, looper 14 advances the same distance as the length of the stitch, and penetrates loop 21 together with thread 15. Looper 14 remains inside the loop 21 (it does not pass through it).

As seen in FIG. 10, the needle 10 begins its upward movement. The threads are tightened, and the process repeats itself during the course of the locking cycle. Looper 14 remains inside the loop.

FIG. 1 1 and 12 describe the ending off of the final locked stitch of the consecutive locked stitches.

As seen in FIG. 1 1 , the needle 10 moves upwards. The gripper element + catcher 25, which also includes a thread cutter, catch thread 15 from looper 14 and grasp it. Looper 14 moves backwards. After looper 14 moves back a certain distance, or immediately after its full retreat, the cutter 25 cuts thread 15, all the while grasping one end (at point 26) of the part of the thread that is threaded in looper 14.

As seen in FIG. 12, looper 14 continues moving until it returns to its original position. The needle 10 continues to ascend and together with the conventional thread pulling mechanism (not shown in FIG. 12) causes the seam to tighten. Catcher 25 releases the end tail of the locking thread. Thread 15 has a tail 28 of about 5 cm long. The length of the free ends 27 is between 5 and 10 mm.

FIG. 13 to FIG. 20 are diagrammatic descriptions of the formation procedure of locked stitches in a two-thread chain stitch machine according to the invention.

As seen in FIG. 13, the needle 10 descends to below the fabric 13 with the upper thread 1 1 . A looper 30 that conducts the lower thread 31 begins to form a loop of chain stitch (as in current technology).

As seen in FIG. 14, when looper 30 moves forward toward the needle 10, loop 32 (of thread 1 1 below the fabric) is formed. Looper 14 moves towards the needle 10, penetrates loop 32 and inserts the securing thread 15. The leading edge 33 of the looper 30 forms a loop 32 whose shape enables looper 14 to penetrate. Looper 14 slides below the fabric in close proximity to the fabrics and above looper 30 and passes alongside and in close proximity to needle 10. The tip of Looper 14 with thread 15 remains inside the loop (it does not pass through it). The needle 10 begins its upward movement.

As seen in FIG. 15, after the needle 10 ascends, the fabric 13 advances. Looper 14 maintains its position relative to the fabric (both movements - that of looper 14 and of the fabrics - are identical and synchronized). Looper 14 remains in its position inside loop 32.

As seen in FIG. 16, after the fabric stops moving, the needle 10 descends into loop 35, which was formed by thread 31. Looper 14 does not move from its place, and maintains its position relative to the fabric, as described in the diagram.

As seen in FIG. 17, after the needle 10 descends, looper 30 moves around the needle (as in conventional chain stitch machines). Looper 14 remains in position without moving.

As seen in FIG. 18, looper 30 penetrates and forms loop 36. Looper 14 advances the same distance as the length of the stitch, and penetrates loop 36 together with the securing thread 15. Looper 14 remains inside the loop (it does not pass through it). The needle 10 begins its upward movement. The threads are tightened, and a new stitching cycle can begin and the process can repeat itself.

FIG. 19 and 20 describe the ending off of the last locked stitch of the consecutive locked stitches.

As seen in FIG. 19, the needle 10 moves upwards. The gripper element + catcher 25, with the thread cutter, catches thread 15 from looper 14 and grasps it. Looper 14 moves backwards. During the retreat of looper 14 or immediately afterwards, the cutter 25 cuts thread 15 at point 37.

As seen in FIG. 20, looper 14 continues moving until it returns to its original location (the length of the free end 28 of the thread 15 is about 5 cm.). The needle 10 continues to ascend and together with the conventional thread pulling mechanism (not shown in FIG. 20) causes the seam to tighten. Catcher 25 releases the end tail of the locking thread. The length of the free ends 27 is between 5 and 10 mm.

There is seen in FIG. 21 parts of a conventional two-thread chain stitch sewing machine having a needle 10 and upper thread 1 1 , and a lower thread 31 , and also there is seen in FIG. 21 the parts of the sewing thread inserting mechanism having a catcher 45 with an open eye, the additional securing thread 15, that is fed out of a spool 16, and a gripper element 25 which has also a catching and cutting thread capability, and an additional looper 46 which has also a catching capability.

The catcher 45 is inserted into several lower loops formed by the upper thread 1 1 under the fabrics in the same manner described in the previous FIG. 13 to FIG 18 for the insertion of the looper 14. Catcher 45 is inserted into the loops of the upper thread without the additional securing thread 15.

Thread 15 is held by the catcher 25 and by catcher 46 as seen in FIG 21.

During the ending off of the last loop of the desired number of locked stitches into which catcher 25 is inserted, the catcher 45 catches thread 15, and immediately after that the catcher 25 releases the end of thread 15.

As seen in FIG. 22, Catcher 45 moves backwards to its original position, thereby inserting thread 15, which is caught in its open eye, into the under loops. The other end of thread 15 is held by catcher 46. After the retreat of catcher 45, the cutter 25, which is also a catcher, moves towards catcher 46, and catches and cuts the additional securing thread 15 in close proximity to catcher 46 in a manner that thread 15 threaded in the under loops is freed.

As seen in FIG. 23, the other end of thread 15, point 50, that is connected to catcher 46 is now pulled by catcher 25 while catcher 46 releases thread 15. Catcher 25 retreats to its original position and then catcher 46 closes on thread 15 and holds it.

As seen in FIG. 24, parts of a conventional two-thread chain stitch sewing machine having a needle 10 and upper thread 1 1 , and a looper 30 threaded with the lower thread 3 1 , and also there is seen in FIG. 24 the parts of the sewing thread inserting mechanism having a catcher 45 with an open eye, and a gripper element 25 which has also a catching and cutting thread capability.

The catcher 45 is inserted into several lower loops formed by the upper thread 1 1 under the fabrics in the same manner described in the previous FIG. 13 to FIG. 18 for the insertion of the looper 14. Catcher 45 is inserted into the loops of the upper thread without an additional securing thread.

During the ending off of the last loop of the desired number of locked stitches into which catcher 45 is inserted, the catcher 45 catches thread 31 at point 55.

As seen in FIG. 25, Catcher 45 moves backwards to its original position, thereby inserting thread 31 , which is caught in its open eye, into the under loops.

If the described locking cycle occurs during the process of sewing the seam, at the desired place along the chain stitch seam, and not at the end of the seam, then after catcher 45 retreats it. releases thread 31 at point 57, and the process of sewing the seam with conventional chain stitches continues until the next locking cycle begins.

If the described locking cycle occurs at the end of the seam, then during or immediately after the retreat of catcher 45, the cutter 25, which is also a catcher, moves towards thread 31. catches it at point 56, and then cuts it in close proximity to the end of the sewn seam. Catcher FIG. 26 depicts a diagrammatic view of a complete one-thread chain stitch seam, after a stitch i has been completed, which includes one regular unlocked chain stitch 43, and several consecutive stitches 42 locked by the securing thread 15.

FIG. 27 describes a diagrammatic view of a complete two-thread chain stitch seam, which includes one regular unlocked chain stitch 41 , and several consecutive locked stitches 40, whereby the upper thread 1 1 is interlocked with the securing thread 1 .

The scope of the described invention is intended to include all embodiments coming within the meaning of the following claims. The foregoing examples illustrate useful forms of the invention specifically for chain stitch sewing machines, but are not to be considered as limiting its scope to such machines or to overlock and interlock machines, as those skilled in the art will be aware that additional variants and modifications of the invention can readily be formulated without departing from the meaning of the following claims.

Claims (2)

1. . A sewing thread inserting mechanism that can insert an additional securing thread into a machine under the fabrics, while a stitch is being formed by the sewing machine in a conventional manner, for the purpose of locking the upper thread, and then when the next stitch is formed by the sewing machine, to repeat the same process and insert the same additional securing thread either from the first locked loop or from the last locked loop without unlocking the previous locked stitch, and to continue the securing cycle process for several consecutive stitches preferably when sewing in a straight line or along a mild curve, said sewing thread inserting mechanism also having the means to grasp and hold the securing thread close to the last locked stitch, externally to said last locked stitch, before and during the time the part of the sewing thread inserting mechanism that inserts the securing thread retreats, said sewing thread inserting mechanism also having the means to cut the securing thread close to the said grasping point while or immediately after the part of the sewing thread inserting mechanism that inserts the securing thread into the locked under-loops retreats to its original position.

2. A sewing thread inserting mechanism as in claim 1 wherein the inserting mechanism comprises a looper with a hole close to its tip, or a catcher, which can be threaded with"" a securing thread, and a gripper element and a catcher and a cutter, said looper or ^ > ΰ{ρ catcher is situated perpendicular to the needle on its left side, having its tip and hole or jDpen eye pointed towards the needle, said looper or catcher being parallel to the feed dog, and being capable of moving under the fabrics, in close proximity to the fabrics and in close proximity to the needle of the sewing machine once the needle penetrates the fabrics, said looper or catcher is capable of moving forward in order to penetrateJ ( &rC?3» i?^ the under-loop formed by the upper thread under the fabrics during the locking cycles, and synchronically and with the same distance and direction as the movement of the fabrics so it will maintain its position relative to the fabrics and the under-loop that is formed in order to lock the desired number of consecutive stitches, typically 3 to 10 consecutive locked stitches, as well as retreating backwards to its original position once the locking cycles are finished, and remaining there until the next locking cycle begins, said gripper element and catcher are capable of grasping and holding the^] (?(7, 0.1«O securing thread close to the looper hole, before and during the time said looper or catcher retreats, and said cutter is capable of cutting the securing thread close to} P&.O said point of grasping while or immediately after said looper retreats to its original position threaded with the other part of the securing thread. A sewing thread inserting mechanism as in claim 1 integrated in a one-thread chain stitch sewing machine, which will lock several consecutive stitches anywhere desired along the seam, preferably when sewing in a straight line or along a mild curve, including the beginning and the end of the seam, by means of an additional securing thread, by interlocking the upper thread and the securing thread. A sewing thread inserting mechanism as in claim 1 integrated in a two-thread chain stitch sewing machine, which will secure several consecutive stitches anywhere desired along the seam, preferably when sewing in a straight line or along a mild curve, including the beginning and the end of the seam, by means of an additional securing thread, by interlocking the upper thread and the securing thread. A sewing thread inserting mechanism as in claim 1 integrated in an overlock sewing machine that also has a safe stitch mechanism, said safe stitch mechanism has the ability to sew a two-thread chain stitch seam, said sewing thread inserting mechanism will secure several consecutive stitches anywhere along said safe seam, preferably when sewing in a straight line or along a mild curve, including the beginning and the end of the seam, by means of an additional securing thread, by interlocking the upper thread of said safe seam and the securing thread. A sewing thread inserting mechanism as in claim 1 integrated in a multi-needle chain stitch sewing machine, which will secure several consecutive stitches anywhere along the seams, preferably when sewing in a straight line or along a mild curve, including the beginning and the end of the seams, by means of an additional securing thread. A sewing thread inserting mechanism as in claim 1 wherein the securing thread may be of any type of conventional thread used in the industries for sewing garments, sportswear, upholstery, etc. A sewing thread inserting mechanism as in claim 1 wherein the inserting mechanism comprises a catcher, which can be threaded with a securing thread, and a gripper element and a catcher and a cutter, said securing threa er v ng om t e sew ng machine's lower and or upper thread, individually or as a tail of a several sewn"1! ^ ^ stitches, said catcher is situated perpendicular to the needle on its left side, having itsj * tip and open eye pointed towards the needle, said catcher being parallel to the feed dog, and being capable of moving under the fabrics, in close proximity to the fabrics and in close proximity to the needle of the sewing machine once the needle penetrates the fabrics, said catcher is capable of moving forward in order to penetrate the under-loop formed by the upper thread under the fabrics during the locking cycles, and synchronically and with the same distance and direction as the movement of the fabrics so it will maintain its position relative to the fabrics and the under-loop that is formed in order to lock the desired number of consecutive stitches, typically 3 to 10 consecutive locked stitches, said catcher being further capable of catching said securing thread from the looper through which it is threaded, as well as retreating backwards to its original position once the locking cycles are finished, and remaining there until the next locking cycle begins, said catcher is also capable of releasing the securing thread once it retreats to its original position, said gripper element and catcher are capable of grasping and holding the securing thread close to the looper hole, after said catcher retreats, and said cutter is capable of cutting the securing thread close to said point of grasping immediately after said catcher retreats to its original position threaded with the securing thread. j A sewing thread inserting mechanism as described hereinbefore and with reference to ] Ο^ζ ^ the accompanying drawings. A sewing machine incorporating the sewing thread inserting mechanism as described^] C i¾ fl£ hereinbefore and with reference to the accompanying drawings. A sewing thread inserting mechanism that can insert an additional securing thread intcT] of. oYt0? several loops made by the upper thread of a chain stitch, overlock or interlock sewing""* machine under the fabrics, while a stitch is being formed by the sewing machine in a conventional manner, for the purpose of locking the upper thread, for several consecutive stitches preferably when sewing in a straight line or along a mild curve. Yair Eilam 37 Hadas St. P.O. Box 3804 Tel-Mond 40600, Israel Applicant