JP5850439B2 - Double chain stitch method and double chain stitch machine - Google Patents

Description

  The present invention uses a double chain stitch sewing machine represented mainly by a horizontal cylindrical shape to form a double chain stitch seam by a needle thread and a looper thread, and this double chain stitch seam is formed. The present invention relates to a double chain stitching method and a double chain stitch sewing machine which perform a fray-stop operation for preventing fraying at an end portion.

  A general double cylindrical sewing machine such as a horizontal cylinder has a needle that holds a needle thread and moves up and down, and a looper that holds a looper thread and moves back and forth in a direction substantially perpendicular to the vertical movement path of the needle. The needle thread loop formed by the needle below the needle plate is captured by the advancement operation of the looper, and the needle thread is looped by the looper thread held by the looper to repeat the other thread looping, A double chain stitch is formed on the sewing fabric.

  As shown in FIG. 24, the structure of a general double chain stitch seam formed by a double chain stitch sewing machine is such that the end of the looper thread 10 cut at the end of sewing is indicated by an arrow in FIG. Is pulled out from the final needle thread loops 20a2 and 20b2 formed by the needle threads 20a and 20b, and the slip-out easily propagates toward the sewing start side. , There is a problem that fraying occurs on the entire seam M.

  FIG. 24 shows a double chain stitch seam M formed by two needle threads 20a, 20b and a looper thread 10. However, the fraying as described above includes one needle thread and a looper thread. This also occurs in the double chain stitch formed by the above.

  For the purpose of preventing fraying peculiar to the seam formed by the double chain stitch sewing machine as described above, the applicant of the present invention is as shown in Japanese Patent Application Laid-Open Nos. 2011-206527 and 2013-6009. A fraying prevention method and a double chain stitch sewing machine with a fraying prevention device have been developed and patent applications have been filed (hereinafter referred to as prior art by the present applicant).

  As shown in FIG. 25 and FIG. 26, the fraying prevention device for the above-mentioned prior art double chain stitch sewing machine (here, a two-needle sewing machine will be described) by the present applicant is shown. 16 to 21) and the needles 2a and 2b that move up and down with respect to the needle drop positions A and A that are set at substantially the center of the needle plate 12 and spaced in the left-right direction (see FIGS. 16 to 21). And the looper 1 that holds the looper thread 10 and can move forward and backward in the direction in which the needle drop positions A and A are aligned, and that captures the needle thread loops 20a2 and 20b2 formed below the needle plate 12 when advanced. 21) and a stand-by position away from the looper 1 as shown in FIG. 25 and a yarn hooking position approaching the looper 1 as shown in FIG. A needle plate centering on the support shaft 30 in the vertical direction across 2 and a circle that is fixed to the upper surface of the middle portion of the thread hook 3 by a fixing screw 60 and swings integrally with the thread hook 3. A looper thread holding body 6 that is curved in an arc shape, a thread operating air cylinder 32 that drives and swings the thread hook 3 and the looper thread holding body 6 to the standby position and the thread hook position, and a needle that is more needle-shaped than the thread hook 3 The needle plate base is disposed at a position away from the plate 12 so that the needle thread loops 20a2 and 20b2 captured by the thread hook 3 at the thread hook position are held at a holding position between the thread hook position and the standby position. 11, a swing lever 9 and a stopper lever 4 that swing about a vertical support shaft 90 in a plane substantially parallel to the needle plate 12 and a part of the swing lever 9. From the engagement position that engages to the engagement position A stopper cylinder 42 that drives and swings to a detached retracted position, a connecting rod 35 that interlocks and connects the thread hook 3 and the swing lever 9, and protrudes forward to the left of the connecting rod 35 and the thread operating cylinder 32. The return spring 91 disposed between the spring hooking portion 95 and the thread operating cylinder 32 and the stopper cylinder 42 are selectively controlled after normal sewing is completed, and the hook at the tip of the yarn hooking hook 3 is controlled. The needle thread loop 20b2 captured by the portion 3b at the yarn hooking position is held at the holding position, and the yarn receiving portion 6a at the tip of the looper yarn holding body 6 is positioned above the looper 1 in front of the hook portion 3b. The controller 8 is configured to maintain this state and perform a sewing operation for at least one stitch (see FIG. 14).

  In addition, the fraying prevention device of the prior art double chain stitch sewing machine by the present applicant is configured such that the needle plate base 11 is formed as an integrated body that is long in the left-right direction. The components and components that are the same as or correspond to the components and components in the anti-fraying device of the double chain stitch sewing machine described as A detailed description thereof will be omitted.

  According to the above-described prior art by the present applicant, after normal sewing is finished, the operations of the thread hook 3, the looper thread holder 6, the stopper lever 4 and the swing lever 9 are controlled via the control unit 8. By performing the sewing operation for one stitch as described above, as shown in FIG. 27, the looper thread 10 is formed on the right side (on the back surface of the sewing fabric at the end of the stitch M of the double ring stitch ( The left final needle thread loop 20b2 passes through the final needle thread loop 20b2 on the left side in FIG. 27 and folds in front of the needle thread 20b that comes out to the back side of the sewing fabric when sewing for one stitch to prevent fraying. The needle thread 20b and the looper thread 10 form a knot-shaped other thread looping as shown in the drawing. On the other hand, the needle thread 20a on the left side (right side in FIG. 27) that slips out to the back side of the sewing fabric when sewing for one stitch is the final needle thread loop 20a2 formed on the back surface of the sewing fabric at the end of normal sewing. The final needle thread loop 20a2 is looped through its own thread. As a result, due to the synergistic effect of the left thread looping part on the left side and the other thread looping on the right knot, no matter which direction the looper thread 10 is applied to, it is specific to the stitch M of the double chain stitch. The occurrence of fraying can be prevented.

  JP 2011-206527 A   JP 2013-6009 A

  As described above, according to the double chain stitch sewing machine according to the prior art by the present applicant, the sewing operation for one stitch for preventing fraying as described above is performed continuously after normal sewing is completed. Therefore, it is possible to effectively prevent the occurrence of fraying peculiar to the double ring stitch. Therefore, it is not necessary to perform a separate process work dedicated to fraying prevention such as tacking after the end of sewing, and it is possible to improve the sewing work efficiency when a large amount of sewn products are continuously produced. However, in the double chain stitch sewing machine according to the prior art by the present applicant, the needle thread portion and the looper yarn portion protruding on the back side of the sewing fabric after the fraying preventing operation by the own yarn looping are used depending on the manner of the cutting process. There remains a problem that the fraying prevention effect due to the thread looping is lowered and the appearance of the sewing product is deteriorated. Hereinafter, this point will be described in detail.

  In the prior art double chain stitch sewing machine by the present applicant, as a thread trimming device 5 for cutting the needle thread portion and the looper thread portion protruding on the back side of the sewing fabric, FIG. 28 (A), As shown in (B), the movable knife 50, the fixed knife 51, and the end of the looper thread 10 that is disposed and cut below the movable knife 50 are elastically sandwiched between the movable knife 50. A looper thread pinching member 52 made of a leaf spring to be held, and a thread pinching auxiliary spring 53 for adjusting the pinching holding force of the looper thread pinching member 52, are sewn on the side edge of the tip of the movable knife 50. A hook-like looper yarn catching portion 50a for hooking and catching the looper yarn portion 10a protruding on the back side of the fabric W is formed, and closer to the proximal end of the movable knife 50 than the looper yarn catching portion 50a. On the side edge, on the back side of the sewing fabric W Put out and left and right needle thread portion thread cutting apparatus in which the hook-shaped needle thread catching portion 50b is formed sequentially captured hooked the 20A1,20b1 5 has been used.

The thread trimming device 5 can be reciprocally driven and moved between a leftward advance position P1 close to the needle plate 12 and the looper 1 and a retreat position P2 right rearward of the advance position P1. Then, after the predetermined (normal) sewing operation is completed, that is, after being driven and moved from the retracted position P2 to the advanced position P1 at the end of sewing, the movable knife 50 is moved to the advanced position P1. Only the reciprocating drive movement is reciprocatingly moved between the position (advance position) closer to one side (right side) of the needle drop positions A and A and the external position closer to the other side (left side) of needle drop positions A and A. The mechanism 70 is linked and linked.
The reciprocating drive moving mechanism 70 linked to the thread trimming device 5 has the same configuration as the reciprocating drive moving mechanism described in detail in the embodiment of the present invention to be described later. The same reference numerals as those of the reciprocating drive moving mechanism in the embodiment are given and described.

Next, the thread trimming operation by the thread trimming device 5 after performing the fraying prevention operation as described above by the above-described prior art double chain stitch sewing machine by the applicant will be described with reference to FIG.
First, as shown in FIG. 29A, after the thread trimming device 5 is moved to the advance position P1, which is an external position closer to one side of the needle drop position, at the end of sewing, as shown in FIG. In addition, only the movable knife 50 is moved forward in the direction of the arrow x from the advance position P1 toward the external position closer to the other side of the needle drop position. By this forward drive movement, as shown in FIG. 29 (c), the looper thread catching portion 50 a on the distal end side of the movable knife 50 is stretched between the vicinity of the distal end of the looper 1 and the back surface side of the sewing fabric W. Immediately after passing the looper thread 10, the moving direction of the movable knife 50 is reversed, and the looper thread part 10a protruding to the back side of the sewing fabric W is hooked and captured by the looper thread capturing part 50a. Subsequently, as shown in FIG. 29 (d), the movable knife 50 is moved backward in the direction of the arrow y from the external position near the other side of the needle drop position toward the advanced position P1, and this backward drive movement. The left and right needle thread portions 20a1 and 20b1 protruding from the back side of the sewing fabric W are sometimes hooked and captured by the needle thread capturing portion 50b. Then, when the movable knife 50 is further driven backward in the direction of the arrow y, as shown in FIG. 29 (e), the needle thread portions 20a1 and 20b1 and the looper thread trapped by the needle thread trapping portion 50b. The looper yarn portion 10 a captured by the portion 50 b is cut by sliding contact between the capturing portions 50 a and 50 b and the fixed knife 51. Thereafter, as shown in FIG. 29 (f), the needles 2 a and 2 b move above the needle plate 12, and the end of the looper thread 10 held by the looper 1 is moved between the movable knife 50 and the looper thread pinching member 52. And is held elastically in between to prepare for the next sewing.

  In the prior art double chain stitch sewing thread trimming device according to the present application that performs the thread trimming operation as described above, the needle thread portions 20a1 and 20b1 and the looper thread projecting to the back side of the sewing fabric W at the end of sewing. By automatically cutting the portion 10a by sliding contact between the movable knife 50 and the fixed knife 51, it is possible to cut to an approximately average length so that there is no variation in the remaining length of each thread. .

  However, in the case of the prior art thread trimming device 5, the cutting positions of the needle thread portions 20a1 and 20b1 and the looper thread portion 10a are separated from the needle drop position so as not to enter the double up and down movement path of the needles 2a and 2b. Since the position is further to the right external position than the right needle 2b, as shown in FIG. 27, the left and right needle thread portions 20a1, 20b1 and the looper thread portion 10a on the back side of the sewing fabric W after cutting are arranged. The remaining thread length from the sewing end remains long.

Further, in the above-described prior art thread trimming device, the cutting position by sliding contact between the movable knife 50 and the fixed knife 51 is brought as close as possible to the needle drop position, and the needle thread portions 20a1, 20b1 and the looper thread portion 10a are cut. Although it is conceivable to shorten the remaining thread length after this, even in this case, the needle thread portions 20a1 and 20b1 are hooked and caught by the needle thread catching portion 50b and then to the cutting position where the fixed knife 51 is located. Since it is moved and cut, there is a limit to shortening the remaining thread length of the needle thread portions 20a1 and 20b1. In particular, the remaining thread length of the left needle thread portion 20a1 is longer than the remaining thread length of the right needle thread portion 20b1 by the pitch of the left and right needles 2a and 2b. Therefore, in the prior art thread trimming device, the cutting position is not as close to the needle drop position as possible, but as shown in FIG. 12 (B), the leading edge edge 51e of the fixed knife 51 and the upper and lower edges of the right needle 2b. By setting a position separated by a sufficient distance d1 from the movement path as a cutting position, each thread has a thread remaining length suitable for cutting by hand-grip described later. is there.

If it does in this way, needle thread part 20a1, 20b1 and looper thread part 10a will remain for a long time on the back side of sewing cloth W at the end of sewing, and it will look out, for example it will protrude from a sewing product, and product value will fall. Invite. Therefore, in order to improve the appearance and increase the value of the product, after the end of sewing, for example, manually cut each thread part on the back side of the sewn fabric W so that the remaining thread length is shortened by using hand kneading. The means to do was taken. However, in this case, it is necessary to perform troublesome manual work for thread cutting at the end of sewing of one sewn product, and as a result, the effects associated with the fraying-preventing operation by the own thread looping, that is, fraying such as tacking Not only is the effect of improving the efficiency of sewing work (improving productivity) unnecessary for separate process work dedicated to fastening, but also easily damaging the sewing fabric W due to hand staking, etc. Variation in yarn remaining length is also likely to occur. In particular, when the thread remaining length is cut to be shorter than necessary, the fraying prevention effect of the folding corner is impaired, and the thread is likely to fray from the stitches after fraying prevention (problem). was there.

The present invention has been made in view of the above-described circumstances, and does not require a separate process such as tacking after sewing, or manual work such as manual knitting , and can significantly increase the efficiency of sewing work. Double chain stitching that can cut the remaining length of each thread protruding on the back side of the fabric to an appropriate length that does not cause the fraying prevention effect of the own thread looping to deteriorate and the appearance of the stitched product to deteriorate. It is an object to provide a method and a double chain stitch sewing machine.

In order to achieve the above object, the double chain stitch method according to the first aspect of the present invention includes a needle thread loop formed by one or a plurality of needles that move up and down while holding the needle thread. Sewing that is detected by the advancement of a looper that can advance and retract in a direction substantially perpendicular to the vertical movement path of the needle, loops the needle thread loop with the looper thread held by the looper, and is fed and moved on the needle plate A double chain stitch method for forming a double chain stitch on a fabric, wherein after the normal sewing is finished with the looper in the advanced state, the needle thread loop captured by the looper is moved from the lowered position of the needle. After the position of the looper thread is held and the looper thread is positioned in front of the lowering position of the needle, the looper thread is prevented from being fed to the looper. Through the needle thread loop captured by the looper Maintaining the position until the needle thread loop is released, and then releasing the position holding of the needle thread loop and causing the needle to perform a sewing operation for at least one stitch including lowering the needle thread loop through the needle thread loop. Looping the needle thread loop with the needle thread held by the needle thread to prevent fraying of the stitches of the double chain stitch, and then the external position closer to one side of the needle drop position on the needle plate and the needle drop position Of the reciprocating drive movement between the two positions of the movable knife which can be reciprocated between the other side position, the movable knife moves from one side position of the needle drop position to the other side position. needle thread when or when the movable knife is forward stroke driven movement is moved backward line drive toward the one side nearer position from the other side toward the outside position, which protrudes on the back side of the sewing fabric towards The needle entry position or needle entry Push cutter cutting or sawing cut by the blade portion formed in the movable knife in the vicinity of the position, followed by the movable knife toward the one side toward the outside position from the other side near the position of the needle drop position go-around The needle drop portion within a range where the looper yarn portion protruding to the back side of the sewing fabric is hooked by the looper yarn catching portion formed on the movable knife when the drive knife is moved and does not enter the vertical movement path of the needle. The looper yarn is transferred to the blade edge portion of the fixed knife arranged close to the blade and cuts the looper yarn portion by sliding contact between the looper yarn catching portion and the blade edge portion of the fixed knife, and the cut looper yarn This end is elastically pinched and held between the movable knife and a looper thread pinching member disposed at the lower part of the movable knife, and waits for the next sewing.

The double chain stitch sewing machine according to the second aspect of the present invention includes one or a plurality of needles that move up and down while holding the needle thread, and a direction that holds the looper thread and is substantially orthogonal to the vertical movement path of the needle. A looper that captures a needle thread loop formed under the needle plate by the needle during the advancement operation, an external position closer to one side of the needle drop position on the needle plate, and a position closer to the other side of the needle drop position. A sewing fabric that is capable of reciprocating driving between the loops of the sewing machine and that is fed and moved on the needle plate by looping the other thread with the looper thread held by the looper. A double chain stitch sewing machine for forming a double chain stitch seam, which is capable of cutting a needle thread portion and a looper thread portion protruding to the back side of the sewing fabric after the double chain stitch stitch is formed. Scalpel and fixed knife and end of looper thread after cutting In a double chain stitch sewing machine having a thread trimming device comprising a looper thread pinching member elastically held between the movable knife and the movable knife, the looper can be moved toward and away from the looper, and the looper can be operated during the approaching operation. The needle thread holding mechanism that holds the needle thread loop captured by the looper at the advancing end side of the looper with respect to the lowering position of the needle, and can be moved toward and away from the looper. A looper thread holding body for holding the extending looper thread at a position in front of the lowering position of the needle, a looper thread restraining mechanism for restraining the feeding of the looper thread to the looper, and the needle thread retaining mechanism and the looper thread retaining body. A control unit that controls the contact and separation operation in association with the operation of the needle and the looper and the feed movement operation of the sewing fabric, and the control unit sets the looper to the advanced position and moves the needle upward. Usually after finishing sewing as the position, the needle thread holding mechanism is brought closer operate than lowered position of the needle the needle thread loop is positioned retained the advanced end of the looper and the looper thread holder The looper thread is moved closer to the looper so that the looper thread is positioned in front of the lowering position of the needle, and then the looper thread restraining mechanism is started to suppress feeding of the looper thread to the looper. The needle is maintained until it is lowered through the needle thread loop captured by the looper, and then the position holding of the needle thread loop is released, the needle is lowered and raised, the looper is advanced and retracted, and The needle thread is held by the needle thread held by the needle by performing a sewing operation for at least one stitch including a lowering of the needle through the needle thread loop together with the feeding operation of the sewing fabric. The loop is looped with its own thread to prevent fraying of the stitches of double chain stitches. The movable knife in the thread trimmer device has the movable knife attached to the needle drop after the fraying prevention operation. Of the reciprocating drive movement between the position closer to the other side of the position and the outer position closer to the one side, the movable knife moves forward from the position closer to one side of the needle drop position toward the outer position closer to the other side. when time or the movable knife is moved backward line drive toward the one side nearer position from the other side toward the outside position is, the needle thread portion projecting on the back side of the sewing cloth the needle location or with blade portion for pushing-away cutting or sawing cut near the needle drop position is formed, the movable knife is moved backward line drive toward the one side toward the outside position from the other side near the position of the needle drop position Before A looper thread catching part for hooking and catching a looper thread part protruding on the back side of the sewing fabric is formed, and the fixed knife and the looper thread pinching member in the thread trimming device have their tips at the ends of the needle. It is arranged at a position approaching the needle drop part within a range that does not enter the vertical movement path, and the movable knife is moved backward from the other side position of the needle drop position toward the one side outer position. The looper yarn portion that is captured by the looper yarn catching portion and transferred to the tip of the fixed knife when cut is cut by sliding contact between the looper yarn catching portion and the fixed knife, and the looper that has been cut An end portion of the thread is elastically sandwiched and held between the movable knife and the looper thread pinching member to wait for the next sewing.

  According to the double chain stitching method according to the first aspect of the present invention and the double chain stitch sewing machine according to the second aspect of the present invention having the above-described characteristic configuration, after the normal sewing is finished with the looper in the advanced state, the looper catches it. The needle thread loop is held at the advancing end side of the looper from the lowering position of the needle, and this state is maintained until the needle is lowered through the needle thread loop captured by the looper, By releasing the position holding of the needle thread loop and performing a sewing operation for at least one stitch including the needle descending through the needle thread loop, the needle thread held by the descending needle is moved forward. Loop the needle thread loop and press the looper thread at this looping section to prevent the looper thread from coming off regardless of the applied tension of the needle thread and looper thread. Perform separate process work Even without, it is possible to prevent the fraying of the seam.

  In addition, after a predetermined sewing operation (after the end of sewing) including a fraying prevention operation by self-thread looping, the movable knife is placed and fixed in a position closer to the other side than the one side outside the needle entry position. The needle thread portion that projects the blade portion of the movable knife toward the back side of the sewing fabric is moved from the external position closer to the other side toward the outer position closer to the other side by moving the blade portion of the movable knife to the needle drop position. Alternatively, it is possible to automatically cut the vicinity of the needle drop position so that the remaining length of the needle thread portion is shortened and aligned to a constant length without variation. On the other hand, the looper thread that protrudes to the back side of the sewing fabric is hooked to the looper thread catch when the movable knife moves backward from the external position near the other side of the needle drop position toward the external position near the one side. After being captured, the tip portion (tip edge of the blade portion) is located closest to the needle drop position in a range where the tip portion (tip edge of the blade portion) does not enter the double up-and-down movement path at a position closer to the other side than the external position near one side. The remaining length of the looper thread is as short as possible by the sliding contact between the fixed knife and the looper thread catching section arranged in such a way that it can be trimmed to a constant length without variation. .

Therefore, at the end of sewing, for example, it is not necessary to perform troublesome manual work such as cutting each thread portion on the back side of the sewing fabric so as to shorten the remaining thread length by using, for example, hand kneading. In combination with fraying prevention by looping, separate work such as tacking is no longer necessary, which significantly improves the sewing work efficiency (productivity) when a large amount of sewing products are continuously produced. In addition to being able to plan, the sewing fabric is damaged by hand-gripping, etc. , and the yarn remaining length is cut shorter than necessary due to variations in the cutting position. As a result, the fraying prevention effect due to the own yarn looping is impaired. As a result, the yarn does not fray from the stitches after fraying prevention, and the finish and appearance of the sewn product can be improved as a whole.

  In particular, in the first and second inventions, the sewing operation for at least one stitch for preventing fraying by self-looping is stopped, or the feed movement of the sewing fabric is stopped or the feed movement amount is smaller than that during normal sewing. By carrying out the movement, the looping portion of the own yarn can be made dense and the looper yarn presser by the looping portion of the own yarn can be strengthened, and the looper yarn can be pulled out at the end of the sewing and can be prevented from fraying. The effect can be further ensured.

In the first and second aspects of the present invention, the blade portion of the movable knife is sewn when the movable knife is moved forward from the position near one side of the needle drop position toward the external position near the other side. The needle thread part formed so as to push and cut the needle thread part protruding to the back side of the needle thread part when the movable knife is moved backward from the outer position near the other side of the needle drop position toward the one side position When the movable knife moves forward from one side closer to the other side toward the other outer position, the needle thread portion is cut and cut from the side surface. Of these, the needle thread portion is pushed all the way down, especially when the movable knife moves forward from one side of the needle drop position toward the other side. What was formed so that it might cut | disconnect is preferable.
In this case, there is no need to make any special shape in order to allow the knife part of the movable knife to pass through the needle thread loop without hindrance. The manufacturing process of the part is simple, and the needle thread part can be cut reliably and sharply.

In the first and second aspects of the present invention, it is preferable to suppress feeding of the looper yarn to the looper after the looper yarn is positioned in front of the lowering position of the needle.
In this case, it is possible to apply a predetermined tension to the looper thread extending from the tip of the looper to the sewing fabric, tightening the looper thread and preventing the looper thread from coming off. The length of the looper thread is short, the appearance of the seam is improved, and the seam quality can be improved.

Further, in the double chain stitch sewing machine according to the second aspect of the invention, apart from the needle thread holding mechanism, the looper thread that is capable of approaching and separating from the looper and extending from the looper to the sewing fabric during the approaching operation is provided. It is preferable that a looper thread holding body for holding the front side or the rear side of the lowering position of the needle is further provided.
In this case, similar to the needle thread holding mechanism, the looper thread extending from the looper to the sewing fabric is lowered by the looper thread holding body that moves close to the looper after the normal sewing is finished with the looper in the advanced state. In addition to the needle thread, the looper thread can be reliably positioned by being held at the front or rear position. Therefore, the own yarn looping can be more reliably performed, and the fraying prevention effect of the seam can be further ensured.

  The double chain stitch sewing machine according to the second aspect of the invention is suitable for the case of a horizontal cylindrical double chain stitch sewing machine. A bed type double chain stitch sewing machine may be the target sewing machine.

1 is an overall external perspective view of a horizontal cylindrical double chain stitch sewing machine according to a first embodiment of the present invention. It is a perspective view which shows the structure of the principal part of the fraying prevention apparatus of the seam in a horizontal cylindrical double chain stitch sewing machine same as the above. It is a perspective view which shows the state which removed a part of structure of the principal part of the fraying prevention apparatus same as the above. It is a top view which shows the structure of the principal part of the fraying prevention apparatus of a seam same as the above. It is a bottom view of the principal part explaining the structure and 1st operation | movement of a stopper mechanism of the fraying prevention apparatus of a seam same as the above. It is a bottom view of the principal part explaining a structure and 2nd operation | movement of a stopper mechanism same as the above. It is a bottom view of the principal part explaining a structure and 3rd operation | movement of a stopper mechanism same as the above. It is a bottom view of the principal part explaining a structure and 4th operation | movement of a stopper mechanism same as the above. It is a disassembled perspective view explaining the structure of the reciprocating drive movement mechanism of the thread trimming device in a horizontal cylindrical double chain stitch sewing machine. The state where the thread trimming device is retracted to the retracted position by the reciprocating drive moving mechanism is shown, (A) is a plan view of the main part, and (B) is a longitudinal sectional view along the line AA in FIG. It is. The state where the thread trimming device is advanced to the advance position by the reciprocating drive moving mechanism is shown, (A) is a plan view of the main part, and (B) is a longitudinal sectional view along the line AA in FIG. 10 (A). It is. In the case of the first embodiment of the present invention and the prior art, the main part for explaining details of the positional relationship between the tip of the fixed knife and the thread pinching member and the vertical reciprocation path of the right needle in the thread trimming device. It is a comparison figure, (A) is the case of 1st embodiment of this invention, (B) is a case of a prior art. It is an enlarged plan view of the movable knife in the thread trimming device of the first embodiment. It is a block diagram which shows the structure of the control system of the horizontal cylinder type double chain stitch sewing machine which concerns on 1st embodiment including the fray prevention device of a seam. It is a time chart which shows the operation content of the control part for fraying prevention of a seam same as the above in time series. It is explanatory drawing of the 1st fraying prevention operation | movement by the fraying prevention apparatus of a seam same as the above. It is explanatory drawing of the 2nd fraying prevention operation | movement by the fraying prevention apparatus of a seam same as the above. It is explanatory drawing of the 3rd fraying prevention operation | movement by the fraying prevention apparatus of a seam same as the above. It is explanatory drawing of the 4th fraying prevention operation | movement by the fraying prevention apparatus of a seam same as the above. It is explanatory drawing of the 5th fraying prevention operation | movement by the fraying prevention apparatus of a seam same as the above. (A)-(f) is a perspective view of the principal part explaining the thread trimming operation | movement of a thread trimming device in order. It is the figure which looked at the structure of the seam of the double ring stitch by the horizontal cylindrical double chain stitch sewing machine which concerns on 1st embodiment from the back surface of the sewing fabric. It is an enlarged plan view of the movable knife of the thread trimming device in the horizontal cylindrical double chain stitch sewing machine according to the second embodiment of the present invention. It is a bottom view which shows schematically the composition of the stitch of the end part of general double chain stitch. It is a top view which shows schematically the structure of the principal part of the fraying prevention apparatus of the stitch in the prior art by this applicant. It is a top view explaining the operation | movement state of the principal part of the fraying prevention apparatus of the stitch in the prior art by this applicant same as the above. It is the figure which looked at the structure of the seam of the double ring stitch obtained by the fray prevention device in the prior art by this applicant same as the above from the back surface of the sewing fabric. The thread cutting device in the prior art by the present applicant is advanced to the advanced position by the reciprocating drive movement mechanism, (A) is a plan view of the main part, and (B) is a CC view of FIG. 28 (A). It is a longitudinal cross-sectional view along a line. (A)-(f) is a perspective view of the principal part explaining in order the thread trimming operation | movement of the thread trimming apparatus in the prior art by this applicant.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an overall external perspective view of a horizontal cylindrical double chain stitch sewing machine according to a first embodiment of the present invention, and FIGS. 2 and 3 are horizontal cylindrical double chain stitch sewing machines according to the first embodiment. FIG. 4 is a plan view showing the configuration of the main part of the fraying prevention device of the seam, and FIGS. 5 to 8 are fraying prevention devices. It is a bottom view of the principal part explaining the structure and first to fourth operations of the stopper mechanism.

FIG. 9 is an exploded perspective view for explaining the configuration of the reciprocating drive moving mechanism in the thread trimming device of the horizontal cylindrical double chain stitch sewing machine, and FIG. 10 is a diagram showing the thread trimming device retracted to the retracted position by the same reciprocating drive moving mechanism. The state is shown, (A) is a plan view of the main part, (B) is a longitudinal sectional view taken along the line AA in FIG. 10 (A), and FIG. The movable knife is moved to the leftmost position, (A) is a plan view of the main part, and (B) is a longitudinal section along the line BB in FIG. 11 (A). FIG.
In the following description, the expressions “left, right” and “front, rear” indicated by arrows in FIGS. 2 to 4 and 9 to 11 will be used. Here, “front” is the side closer to the sewing manufacturer, “rear” is the side away from the sewing manufacturer, and “left, right” is “left, right” when viewed from the front closer to the sewing manufacturer. It is.

  As shown in FIG. 1, in the horizontal cylindrical double chain stitch sewing machine according to the first embodiment, the sewing machine arm portion C and the sewing bed portion B are substantially parallel to each other from the vertical position of the sewing machine main body D toward the left. It is extended in the shape. Inside the sewing machine arm portion C, there are a transmission rotation shaft, a needle drive mechanism for reciprocating the left and right needles 2a, 2b up and down, a presser drive mechanism for reciprocating the cloth presser 25 up and down, and power transmission to these drive mechanisms. Although a mechanism and the like are incorporated, the drive mechanism and the power transmission mechanism are well known, and thus description thereof is omitted.

  Further, as shown in FIG. 4, the horizontal cylindrical double chain stitch sewing machine includes a looper 1, left and right needles 2a and 2b (see FIGS. 16 to 21), and needles attached to the upper surface of the sewing machine bed portion B. A plate base 11, a fraying preventing device H for stitches provided on the needle plate base 11, and a needle plate 12 attached on the needle plate base 11 are provided.

  In the sewing machine bed portion B below the needle plate 12, a looper 1 that holds a looper thread 10 and moves back and forth in the left-right direction substantially perpendicular to the vertical movement path of the needles 2a and 2b, and a thread trimmer 5 The blade edge 51e of the fixed knife 51 of the thread trimmer 5 is a position close to the needle plate 12 and the looper 1 as shown in FIGS. 10A and 10B, which will be described later. Between a left forward advance position P1 where a contact member 34, which will be described later, comes into contact with the stopper member 33, and a retreat position P2 to the right rear of the advance position P1 as shown in FIGS. 11A and 11B. In the state where the thread trimming device 5 is moved to the advance position P1, only the movable knife 50, which will be described later, is moved closer to one side (right side) and the other side (left side) of the needle drop position. Directly in the xy direction between external positions Reciprocating movement mechanism 70 or the like reciprocally drives the movement is incorporated in manner.

  The left and right needles 2a, 2b are attached to the lower end of a needle bar (not shown) that rises and falls in conjunction with the rotation of a transmission rotation shaft (not shown) in the sewing machine arm C. A and A in FIGS. 2 and 4 indicate the needle drop positions (lower positions) of the needles 2a and 2b. The needle drop positions A and A are set at a substantially central portion of the needle plate 12 with a gap in the left-right direction.

  The looper 1 is disposed in the sewing machine bed portion B, and advances and retreats in the direction in which the needles 2a and 2b are arranged substantially perpendicularly to the vertical reciprocating path of the needles 2a and 2b through the operation of a looper driving mechanism (not shown). Left and right) The solid line in FIG. 4 shows a state where the looper 1 is moved to the leftward position, and the broken line in FIG. 4 shows a state where the looper 1 is moved to the rightward position. As shown by the solid line in FIG. 4, the tip of the looper 1 in the leftward position extends leftward beyond the needle drop positions A and A, and is in the rightward position as shown by the broken line in FIG. The tip of the looper 1 is located to the right of the needle drop positions A and A.

  The horizontal cylindrical double chain stitch sewing machine sews a sewing fabric (not shown) set on the needle plate 12 by the upward and downward movements of the needles 2a and 2b and the leftward and rightward movements of the looper 1. The sewing fabric is pressed onto the needle plate 12 by the presser foot 25 and is fed and moved in the direction of arrow Y in FIG. 4 by the operation of the feed mechanism provided inside the sewing machine bed B. The feed mechanism is provided with a feed dog that protrudes on the needle plate 12 and moves backward, and repeats an operation of immersing under the needle plate 12 and returning to the front direction. Is moved in the direction of arrow Y.

  The needle bar, the looper drive mechanism, and the feed mechanism described above are known mechanisms that operate in synchronization with each other by transmission from a transmission rotation shaft (not shown). The needles 2a and 2b hold the needle threads 20a and 20b (see FIGS. 16 to 21), and pass through the sewing cloth and reach the bottom of the needle plate 12 while the sewing cloth stops moving. Then, it rises and comes out above the sewing fabric. The looper 1 holds the looper thread 10 (see FIGS. 16 to 21), moves to the left as the needles 2a and 2b start to rise, and loops 20a2 of needle threads 20a and 20b formed below the needle plate 12. Capture 20b2. The sewing fabric is fed and moved when the needles 2a and 2b are raised. The needles 2a and 2b descend through the sewing fabric that has been fed and catch the looper thread 10 held by the looper 1 that is retracting to the right. The double chain stitch sewing machine repeats the above operation to form double chain stitch stitches on the sewing fabric.

  First, the fraying prevention device H of the seam provided in the above-described horizontal cylindrical double chain stitch sewing machine will be described in detail. The fray prevention device H is a connecting member that interlocks and connects a needle thread holding mechanism, a stopper mechanism, a thread hook 3 (described later) of the needle thread holding mechanism, and a stopper member 4 (described later) of the stopper mechanism. Connecting rod 35 and a control unit 8 (described later).

  The needle thread holding mechanism has a vertical hook 30 that extends between a thread hook 3 and a standby position where the thread hook 3 is separated from the looper 1 and a thread hook position close to the looper 1. And a reciprocating type thread manipulating cylinder 32 that is driven and oscillated as a center. A support shaft 30 serving as a swing center of the thread hook 3 is disposed in the vicinity of the right rear corner of the needle plate 12 and supported on the needle plate base 11.

  The thread hook 3 has an arcuate curved shape, and is continuously connected to the front end portion of the support arm 3e extending leftward from the support shaft 30 so as to be folded forward. The front end portion of the thread hook 3 faces the needle drop positions A and A from the rear left side on the lower side of the needle plate 12, and a hook portion 3b protruding outward is formed at the front end portion. Yes. The support arm 3e has an extending portion 3c that extends forward from the support shaft 30, and one end portion of the connecting rod 35 is connected to the distal end portion of the extending portion 3c.

  As shown in FIG. 4, a looper yarn holder 6 having an arcuate curved shape is fastened to the base portion of the yarn hook 3 through two fixing screws 60, 60. The tip of the looper thread holder 6 extends forward substantially along the left side of the yarn hook 3 and faces the needle drop positions A and A at the front position of the tip of the yarn hook 3. A looper yarn receiving portion 6 a that is bifurcated is formed at the tip of the looper yarn holding body 6. The position of the looper thread holding body 6 relative to the thread hook 3 can be adjusted by loosening the fixing screws 60, 60, and this position adjustment ensures that the looper thread 10 is held by the looper thread receiving portion 6a at the tip. It is configured as follows.

  As shown in FIGS. 5 to 8, the stopper mechanism is fixed to the distal end portion (left end portion) of the output rod 31 of the yarn operation cylinder 32 via a set screw 36 and supplied via an air tube 33. A stopper member 14 that is linearly driven to reciprocate in the left-right direction when the yarn operation cylinder 32 is expanded and contracted by the operating air, and a swing lever 9 that can be engaged with and released from a part of the stopper member 14. The spring 96 that engages the swing lever 9 with a part of the stopper member 14 and biases the thread hook 3 in the direction in which the thread hook 3 is located at the standby position, and the swing biasing force of the spring 96 On the other hand, the swing lever 9 is configured by a one-motion type (extrusion drive type in the left direction) stopper cylinder 42 that forcibly releases the engagement from a part of the stopper member 14.

  The output rod 41 of the stopper cylinder 42 causes the swing lever 9 to swing the bias force of the spring 96 as the stopper cylinder 42 is pushed out and driven by the operating air supplied through the air tube 43. It is configured to swing counterclockwise against this.

  The swing lever 9 is supported on the upper surface of the swing lever mounting base 92 so as to be swingable about a vertical support shaft 90. The swing lever 9 has an engaging claw 9a that can be engaged with a part of the stopper member 14 at the tip, and as shown in FIG. 5, the extension operation of the thread operation cylinder 32 (see FIG. 3). When the stopper member 14 is driven to move to the left by the above, that is, when the yarn hook 3 is moved to the standby position, the biasing force of the spring 96 contacts the side of the stopper member 14 and the yarn When the stopper member 14 is moved to the right by the contraction operation of the operation cylinder 32, as shown in FIG. The engaging claw 9a can be engaged with a part of the stopper member 14.

  Further, as shown in FIG. 7, when the contracted thread operation cylinder 32 (see FIG. 3) is again extended by a small amount, the engaging claw 9a at the tip of the swing lever 9 is engaged with a part of the stopper member 14. Accordingly, the leftward movement of the stopper member 14 is temporarily stopped. In this state where the stopper member 14 is temporarily stopped, the thread hook 3 is moved to the holding position between the standby position and the thread hook position via the connecting rod 35 and stopped. At this time, the hook portion 3b at the tip of the thread hook 3 moves leftward and rearward from the thread hook position (needle drop positions A and A) shown in FIG. 4 and hooks the needle threads 20a and 20b to hold the holding position. Hold on.

  Further, as shown in FIG. 8, the output rod 41 is pushed out to the left as the stopper cylinder 42 is extended, so that the swing lever 9 is counterclockwise against the swing biasing force of the spring 96. The engaging claw 9a at the tip of the swing lever 9 is disengaged from a part of the stopper member 14, and the temporary stop of the stopper member 14 is released. As a result, the thread operating cylinder 32 is extended to the maximum, and the thread hook 3 is returned to the standby position via the connecting rod 35.

  As described above, in the first embodiment, the thread hook 3 of the needle thread holding mechanism is moved between the standby position, the thread hook position, and the holding position by the expansion and contraction operations of the thread operation cylinder 32 and the stopper cylinder 42. Swing over

  Further, in the horizontal cylindrical double chain stitch sewing machine according to the first embodiment, the needle plate base 11 attached to the upper surface of the sewing machine bed portion B has a left needle plate base portion as shown in FIGS. 11L and the right throat plate base part 11R are divided into two parts. The needle plate 12 is detachably attached to the upper surface of the left needle plate base 11L via a set screw 100, and a support shaft 30 serving as a swing center of the thread hook 3 of the needle thread holding mechanism is provided. I support it.

  The needle plate near the front end (left end) near the left end of the left needle plate base 11L divided into two parts, specifically, near the front end (left end) of the sewing machine arm portion C indicated by the phantom line in FIG. A screw hole 101 is formed at a location apart from the attachment location of 12, and the left throat plate base portion 11 </ b> L is fastened to the upper surface of the sewing machine bed portion B via a set screw member 102 screwed into the screw hole 101. It is attached so that it can be fixed and released (removable).

  Further, as shown in FIG. 3, the upper surface of the sewing machine bed portion B and the left throat plate base portion 11L are provided with knock pins 103 and the knock pins 103 at locations apart from the two fastening fixing locations by the set screw member 102. A pin hole 104 to be fitted is formed, and the left needle plate base portion 11L is positioned at a predetermined position and posture with respect to the sewing machine bed portion B by inserting and fitting the pin hole 104 into the knock pin 103 from above. In this state, the left needle plate base 11L can be fastened and fixed to the upper surface of the sewing machine bed B by screwing the set screw member 102 into the screw hole 101.

  In the first embodiment, the knock pin 103 is protruded upward from the upper surface of the sewing machine bed portion B, and the pin hole 104 is formed and formed in the left throat plate base portion 11L. The knock pin 103 may protrude downward from the lower surface of the left needle plate base 11L, and the pin hole 104 may be formed on the upper surface of the sewing machine bed portion B.

  On the other hand, the right needle plate base portion 11R divided into two forms a cylinder mounting base portion that supports the thread operating cylinder 32 and the stopper cylinder 42 (hereinafter, the right needle plate base portion 11R is referred to as a cylinder mounting base portion). The above-described stopper mechanism is disposed below the cylinder mount 11R. Specifically, as shown in FIGS. 5 to 8, the thread operating cylinder 32 is fixedly supported on the lower surface of the cylinder mounting base portion 11 </ b> R via the mounting screw 105, and at the lower part of the thread operating cylinder 32. The stopper cylinders 42 are arranged in a two-tiered manner, and the stopper cylinders 42 are fixedly supported on the cylinder mounting base portion 11R via mounting screws 106.

  The cylinder mount 11R is assembled to the rear surface of the sewing machine bed B in a fixed state via a set screw member 107. Here, the fixed state means that the anti-fraying device H is fixed to a predetermined position by tightening the set screw member 107 when the anti-fraying device H is assembled to the sewing machine bed portion B. Refers to the state fixed in position.

  One end (right end) portion of the connecting rod 35 is rotatably connected to a stopper member 14 in a stopper mechanism by a pin screw 108. A stopper member that linearly reciprocates in the left-right direction along with the expansion and contraction of the thread operating cylinder 32 is provided on the cylinder mounting base 11R at a position corresponding to the connecting portion of the one end of the connecting rod 35 and the stopper member 14 by the pin screw 108. A long slot 109 is formed along the left-right direction so as to allow 14 linear reciprocations.

  Further, a connecting end portion 35a connected to the extending portion 3c connected to the yarn hook 3 at the other end of the connecting rod 35 is bent downward by substantially the thickness of the extending portion 3c. A pin 110 protrudes upward from the connecting end portion 35a of the connecting rod 35 bent downward, and can be inserted into the extended portion 3c from above the pin 110. Further, a connecting hole 111 that can be extracted upward is formed.

  As a result, when the left needle plate base 11L is released from the sewing machine bed B after being unfixed from the sewing machine bed B, the connecting rod 35 and the extending part 3c are fixedly connected, for example, a set screw or the like is loosened. Then, it is not necessary to perform the operation of releasing the interlocking state of both, and by simply lifting the left throat plate base 11L upward, the connection hole 111 of the extending portion 3c is extracted upward from the pin 110 and connected to the connection rod 35. It is possible to release the interlocking state with the extending portion 3c (thread hook 3). Further, when attaching the left needle plate base 11L to the sewing machine bed portion B, the connecting hole 111 is inserted into the pin 110 from above only by moving the left needle plate base 11L from above toward the sewing bed portion B. It is possible to return the connecting rod 35 and the extending portion 3c (thread hook 3) to the interlocking state. The connecting end portion 35a of the connecting rod 35 does not necessarily have to be bent downward. That is, the connecting rod 35 may have a flat plate shape over its entire length.

  Further, a swing lever mounting base 92 that supports the swing lever 9 in the stopper mechanism so as to be swingable about a vertical support shaft 90 is fixed to the cylinder mounting base portion 11R with a long slot 93 in the left-right direction. It is attached to the left and right via a screw 94 so that the position can be adjusted. This is because the swing lever mounting base 92 is adjusted to the left and right with respect to the cylinder mounting base portion 11R even after the cylinder mounting base portion 11R is fixed to the sewing machine bed portion B via the set screw member 107. As a result, it is possible to arbitrarily adjust the timing at which the looper 1 comes out of the needle thread loops 20a2 and 20b2 held by the thread hook 3, so that self-looping for preventing fraying of the seams can be ensured. It is comprised so that it can be made to carry out.

  As described above, in the horizontal cylindrical double chain stitch sewing machine according to the first embodiment, the needle plate base 11 is divided into the left needle plate base portion 11L and the right needle plate base portion 11R. Accordingly, when the fraying prevention device H of the seam is assembled to the sewing machine bed portion B, the left needle plate base portion 11L and the right cylinder mounting base portion 11R of the needle plate base 11 divided into right and left are divided. Can be individually attached to the sewing machine bed portion B. Therefore, as compared with the case where the left and right side needle plate bases 11L and 11R are integrated to handle one long and large needle plate base, the attachment (assembly) work to the sewing machine bed B of the entire fray prevention device H is performed. It can be done easily with little effort.

  Further, after the needle plate base 11 (the left needle plate base portion 11L and the right cylinder mounting base portion 11R) is once assembled to the sewing machine bed portion B, the needle plate base 11 such as the looper 1 or its operating member is used. When it is necessary to adjust the sewing tone by correcting the position and movement locus of the members constituting the sewing housed inside the sewing machine bed B at the lower part, or at the lower part of the needle plate base 11 When maintenance such as repair or replacement of various parts housed in the bed part B becomes necessary, the thread operating cylinder 32 and the stopper cylinder 43 to which the air tubes 33 and 43 are connected are set at predetermined positions. It is not necessary to remove the cylinder mounting base portion 11R which is firmly fixed to the sewing machine bed B, and only the left needle plate base 11L is released from the sewing machine bed B by being unfixed. It is possible to easily perform the adjustment and maintenance of sewing tone to ensure a sufficiently large work space only.

  Next, the thread trimming mechanism 5 provided in the horizontal cylindrical double chain stitch sewing machine according to the first embodiment will be described. As shown in FIGS. 9 to 11, the thread trimming mechanism 5 includes the advance position P1 and the advance position where the thread trimming device 5 is close to the needle plate 12 and the looper 1 via the reciprocating drive moving mechanism 70. A reciprocating drive movement is possible between the retreat position P2 on the right rear side of the position P1. Then, the thread trimming device 5 is used for cutting a thread that cuts the left and right needle thread portions 20a1, 20b1 and the looper thread portion 10a that protrude to the back side of the sewing fabric W at the end of a predetermined sewing operation, that is, at the end of sewing. The fixed knife 51e is arranged at a position closest to the needle drop position within the movable knife 50 and the left and right needles 2a, 2b that do not fall within the vertical movement path of the right needle 2b at the advance position P1. A knife 51, a looper thread clamping member 52 made of a leaf spring that elastically clamps and holds the end of the looper thread 10 disposed and cut below the movable knife 50, and the movable knife 50; A loop clamp auxiliary spring 53 for adjusting the clamp holding force of the looper thread clamp member 52.

Here, the position of the fixed knife 51 and looper thread pinching member 52 at the advanced position P1 in the case of the first embodiment, and the fixed knife 51 and looper thread at the advanced position P1 in the case of the prior art by the present applicant. The relationship with the position of the pinching member 52 will be specifically described with reference to the comparison diagrams of FIGS.
FIG. 12A shows the positions of the fixed knife 51 and the looper thread pinching member 52 in the case of the first embodiment, and FIG. 12B shows those positions in the case of the prior art. In the case of the first embodiment, as shown in FIG. 12A, between the tip of the blade edge 51e of the fixed knife 51 and the tip 52e of the looper thread pinching member 52 and the vertical movement path of the right needle 2b. The distance d of the right hand 2b is as close to zero as possible and smaller than the distance d1 of the prior art (d <d1), that is, it is positioned as close as possible to the vertical movement path of the right needle 2b. Thus, the fixed knife 52 and the looper thread pinching member 52 are formed to extend longer toward the left as compared with the prior art shown in FIG.

  As shown in FIG. 13, the movable knife 50 is composed of a strip-shaped plate material that is long in the left-right direction, and the movable knife 50 is located at the advancing position P1 at a position near the tip of the movable knife 50 made of this long strip-shaped plate material. The right and left needles projecting to the back side of the sewing fabric W on the throat plate 12 when moving forward from one side (right side) near the needle drop position toward the other side (left side). The blade portion 50e has a blade portion 50e that sequentially pushes and cuts the yarn portions 20b1 and 20a1 in the vicinity of the needle drop position A, A or the vicinity of the needle drop position A, A. It is formed to be located on the side.

  In addition, at the tip of the movable knife 50 made of the long belt-like plate material, the movable knife 50 is driven backward from the external position closer to the other side (left side) of the needle drop position toward the outer position closer to one side (right side). When moved, a looper thread catching portion 50a for catching and catching the looper thread portion 10a protruding on the back side of the sewing fabric W on the needle plate 12 is formed, and is captured by the looper thread catching portion 50a. The looper yarn portion 10a is moved to the position closer to the other side (right side) than the external position closer to one side (right side) of the needle drop position, and the looper yarn catching portion 50a and the blade edge portion 51e of the fixed blade 51, It is comprised so that it may cut | disconnect by sliding contact.

The thread trimming device 5 is reciprocated between the advance position P1 and the retracted position P2, and only the movable knife 50 is needled in a state where the thread trimming device 5 is moved to the advance position P1. A reciprocating drive moving mechanism 70 for linearly reciprocatingly moving in the xy direction between an external position closer to one side (right side) and an outer position closer to the other side (left side) is shown in FIGS. (A), (B) and FIG. 11 (A), (B) is comprised.
In other words, the movable knife 50 has its right end lower surface fixed to the movable knife table 124 via the screw 123. A U-shaped notch 125 is formed at a substantially central portion in the longitudinal direction (left-right direction) of the movable knife base 124, and the longitudinal direction of the movable knife base 124 is located at the left and right positions sandwiching the notch 125. A pair of long left and right slits 126a and 126b are formed along the line.

  The fixed knife 51 is disposed on the upper surface of the movable knife 50, and the knife table guide 127 and the right end portion of the looper thread pinching member 52 are arranged on the lower surface of the right end portion of the fixed knife 51. The fixed knife 51, the knife table guide 127, and the looper thread pinching member 52 are fixed to the left end portion of the fixed knife table 129 via screws 128. The movable knife table 124 includes a headed bolt 148 inserted into the back surface (lower surface) of the fixed knife table 129 and a columnar nut 131a with a flange inserted into one end of a pair of left and right links 140a and 140b from the upper surface side. 131b, the flanged columnar nuts 131a, 131b allow rotation of one end of the pair of left and right links 140a, 140b, and the pair of left and right slits 126a, 126b in the movable knife base 124. It is clamped in a state in which it can slide and move within the length range.

The other ends of the pair of left and right links 140a and 140b are inserted from the upper surface side thereof, and the flanged sleeves 141a and 141b that allow rotation in the other end of the pair of left and right links 140a and 140b are countersunk screws 142a, It is screwed to the device mounting base 130 via 142b. As a result, the movable knife base 124 and the fixed knife base 129 are supported by the device mounting base 130 so as to be able to reciprocate in the left-right direction as the pair of left and right links 140a, 140b swing.
Of the flanged sleeves 141a and 141b, the right flanged sleeve 141b changes the pitch of the holes on both ends of the right link 140b, thereby using the flanged sleeve 141a of the left link 140a as a fulcrum. In order to enable fine adjustment of the needle drop position of the movable knife 50 at the advance position P1 and the position of the advance movement start point in the cloth feed direction with respect to the looper 1, the shape is formed in an eccentric cam shape.

  The fixed knife base 129 is formed with a contact member 134 that comes into contact with a stopper member 133 screwed to the device mounting base 130 at a position below the left link 140a of the pair of left and right links 140a and 140b.

  In addition, an engagement protrusion 136 that contacts and separates from a protrusion 135 that protrudes rearward from a position slightly to the right of the left end of the movable knife base 124 is formed at the rear part of the center portion in the longitudinal direction of the fixed knife base 129. . When the engagement protrusion 136 abuts on the protrusion 135, the movable knife base 124 is configured so that it cannot move further to the right by itself. Further, the movable knife base 124 is elastically fixed so as to always move to the left via a spring 137 that is screwed to the device mounting base 130 and has one end elastically contacted with the right end surface of the contact member 134. Is energized.

  The device mounting base 130 is formed with a groove 146 into which the fixed knife base 129 is slidably inserted in the left-right direction, and is fixed to the sewing machine bed portion B via a plurality of screws 147 disposed around the device mounting base 130. ing. Further, the device mounting base 130 is pivotally connected to the tip of the piston 148 of the thread trimming air cylinder 48 via a stepped screw 143, and is connected to the device mounting base 130 in the direction of arrows ab about the shaft 144. A drive lever 145 capable of driving and swinging is attached. A tapered circular portion 145 a at the tip of the drive lever 145 is engaged with a U-shaped cutout portion 125 formed at a substantially central portion of the movable knife base 124.

  According to the reciprocating drive moving mechanism 70 configured as described above, the drive lever 145 is driven in the direction b by the extension of the piston 148 of the thread trimming air cylinder 48, as shown in FIGS. When swinging, the thread trimmer 5 moves to the right against the elastic biasing force of the spring 137 so that the engaging projection 136 and the projection 135 are in contact with each other, and the pair of left and right links 140a. , 140b of the cylindrical nuts 131a, 131b move to the leftmost side of the pair of left and right slits 126a, 126b, and the left end surface of the contact member 134 of the fixed knife base 129 is separated from the stopper member 133. In this state, the thread trimming device 5 is at the retracted position P2, and is waiting in an inclined posture that does not hinder the movement of the looper 1.

  Then, as shown in FIGS. 11A and 11B, when the drive lever 145 is driven and swung in the direction a by the contraction of the piston 148, the contact member 134 of the fixed knife base 129 is made elastic by the spring 137. Move to the left by force. Accordingly, the thread trimming device 5 reduces the inclination angle of the inclined posture by the swing of the pair of left and right links 140a and 140b while the engagement protrusion 136 and the protrusion 135 are in contact with each other. The contact member 134 moves to the left until the left end surface of the contact member 134 contacts the stopper member 133. As a result, the thread trimming device 5 moves to the advance position P1 and assumes a posture substantially orthogonal to the sewing progressing direction.

  When the piston 148 is further contracted from this state and the drive lever 145 is driven and swung in the direction a, the movable knife base 124 drops the needle drop on the needle plate P while the fixed knife base 129 remains at the advanced position P1. Move to the left (x direction) through the position. That is, only the movable knife 50 fixed to the movable knife table 124 moves leftward (forward movement) between the needle plate 12 and the looper 1. At this time, the movable knife table 124 and the fixed knife table 129 are supported by the device mounting table 130 in a state in which the movable knife table 124 and the pair of left and right links 140a and 140b can reciprocate in the left and right directions. The knife 50 is controlled to move linearly by a pair of left and right links 140a and 140b.

  Next, when the piston 148 is extended, the drive lever 145 is driven to swing in the direction b. Along with this, the movable knife 50 moves in the right direction (y direction) from the position to the left most, and moves backward (reverse movement) to the lower part of the stationary knife 51 waiting at the advance position P1. When the piston 148 further contracts from this state, the thread trimming device 5 is moved backward to the retracted position P2 shown in FIGS. 10 (A) and 10 (B).

In addition to the configuration and apparatus described above, the double chain stitch sewing machine of the first embodiment includes a needle thread presser device 55 and a thread loosening device.
As shown in FIG. 1, the needle thread presser device 55 is attached to a sewing machine arm portion C above the needle plate 12 via a bracket 56. Although not shown, the needle thread presser device 55 is configured to abut and separate a pair of front and rear needle thread presser plates through an air cylinder and a spring, and the thread trimmer device 5 can be moved at the end of sewing. When the knife 50 pushes and cuts the needle thread portions 20a1 and 20b1, the needle threads 20a and 20b are pressed and held in the upper part of the needle plate 12 by the contact of the pair of needle thread presser plates. Thus, the needle thread portions 20a1 and 20b1 are cut and cut by the blade portion 50e of the movable knife 50 with certainty.

  The thread loosening device floats the thread tension plates 57 and 58 (see FIG. 1) simultaneously with the start of the forward drive movement of the movable knife 50 (relaxes the thread tightening), and the needle threads 20a and 20b and the looper. The yarn 10 is fed out instantaneously. By the loosening of the looper yarn 10 by the yarn loosening device, the looper yarn 10 hooked and caught by the looper yarn catching portion 50a of the movable knife 50 is caused by sliding contact between the blade edge 51e of the fixed knife 51 and the looper yarn catching portion 50a. The movement of the movable knife 50 when moved to the cutting position can be stabilized. Further, when the sewing cloth W is taken out from the needle plate 12 after cutting each thread by the movable knife 50, the needle threads 20a and 20b are slightly pulled out due to the resistance of the needle threads 20a and 20b to come off from the sewing cloth W, and the next sewing is performed. Eye formation can be stabilized.

FIG. 14 is a block diagram showing the configuration of the control system of the horizontal cylindrical double chain stitch sewing machine according to the first embodiment including the seam fray prevention device H and the thread trimming device 5 as described above.
The control unit 8 of the double chain stitch sewing machine includes a depression signal 21a and a return signal 21b by the pedal switch 21, a needle position signal 22 transmitted when the needles 2a and 2b are in the vicinity of the top dead center, and a thread trimming. A signal 23 and a needle thread wiping signal 24 are input.

  On the other hand, the control unit 8 outputs an operation control signal to each of the yarn operation cylinder 32, the stopper cylinder 42, and the yarn cutting air cylinder 48. The yarn hook 3 and the looper yarn holder 6 operate as described above in accordance with the operation control signals output from the control unit 8 to the yarn operation cylinder 32 and the stopper cylinder 42, and the yarn cutting air cylinder 48 is supplied from the control unit 8. Each expansion / contraction operation is performed according to the output thread trimming signal 23.

  Further, the control unit 8 includes a sewing machine motor 80 that is a drive source of the transmission rotating shaft, a presser cylinder 81 that raises and lowers the presser foot, an air wiper 82 that jumps up the needle threads 20a and 20b that are cut as will be described later, and a sewing fabric. Operation control signals are also output to the feed reduction mechanism 83 that adjusts the feed amount of the looper and the looper yarn suppression mechanism 84 that suppresses the feed of the looper yarn 10 to the looper 1.

  The feed reduction mechanism 83 changes the operation mode of the feed dog in the feed mechanism, for example, by tilting the operation path of the feed dog with respect to the needle plate 12 and shortening the protrusion time on the needle plate P, The feed time of the sewing fabric is reduced by shortening the time during which the feed dog acts on the sewing fabric 12 or by changing the length of the lever that circulates the feed dog to reduce the unit feed pitch by the feed dog. Since the feed reduction mechanism 83 is known in the art, detailed illustration and description thereof will be omitted.

The looper yarn suppressing mechanism 84 includes a yarn tension plate that clamps a midway portion of the looper yarn 10 that is fed into the looper 1, and an actuator that operates to increase or decrease the looper yarn clamping strength of the yarn tension plate. By increasing the looper yarn clamping strength by the tension plate and increasing the resistance applied to the looper yarn 10, the feeding of the looper yarn 10 is suppressed, and such a looper yarn suppressing mechanism 84 is also known. Detailed illustration and description are omitted.

  The control unit 8 associates the thread hook 3 with the sewing machine motor 80, the presser foot cylinder 81, the air wiper 82, the feed reduction mechanism 83, and the looper thread suppression mechanism 84 after the end of forming the double chain stitch. The fraying prevention operation and the thread trimming operation of the stitches of the double chain stitch are executed.

  FIG. 15 is a time chart showing the operation contents of the control unit 8 for preventing fraying in time series. The control unit 8 is a computer including a CPU, a ROM, and a RAM, and the fraying prevention operation and the thread trimming operation according to the time chart of FIG. 15 are executed by a series of operations of the CPU based on a control program stored in the ROM. .

  16-20 is explanatory drawing of the fraying prevention operation | movement by the fraying prevention apparatus H in the horizontal cylindrical double chain stitch sewing machine which concerns on 1st embodiment, and arises by operation | movement of the control part 8 according to the time chart of FIG. The operating state of the thread hook 3 and the looper thread holder 6 is shown.

  When a sewing manufacturer using a sewing machine finishes normal sewing, he / she stops stepping on the pedal for driving the sewing machine and then performs fraying prevention operation. In this case, depress the pedal. Manipulate. The pedal switch 21 is attached to the pedal, and outputs a depression signal 21a during a depression operation, and outputs a depression signal 21b when a depression operation is performed.

  When the normal sewing is finished and the pedal for driving the sewing machine is returned from the depressed state to the neutral state, that is, the control unit 8 performs the depression signal 21a and the depression from the pedal switch 21. When none of the signals 21b is output, a stop command is output to the sewing machine motor 80 with reference to the needle position signal 22 given to the input side. As a result, the sewing machine temporarily stops in a state where the hands 2a and 2b are in the vicinity of the top dead center and the looper 1 is moved leftward.

  Thereafter, the control unit 8 stands by until the pedal is turned back. When the stepping-back operation is performed at the time point S2 in FIG. 15 and the stepping-back signal 21b is input to the input side, the control unit 8 first gives an operation start command to the feed reduction mechanism 83 at the time point S3 to feed the feed dog. The feed amount of the sewing fabric is made smaller (reduced) than the feed amount at the time of normal sewing, for example, by reducing the unit feed pitch by, and then the fraying prevention operation described below is started. In the feed reduction mechanism 83, the feed start timing (S3) of a small feed amount of the sewing fabric by the feed dog is set so that the thread thread hook 3 causes the needle thread loops 20a2 and 20b2 to move from the lower position of the needles 2a and 2b. It is set one stitch before being positioned on the advancing end side.

  The control unit 8 returns to the normal sewing operation when the depression signal 21a is input again from the pedal switch 21, so that the sewing manufacturer continues the normal sewing by depressing the pedal again. be able to. Further, in FIG. 15, the neutral state is to be maintained from the time point S1 to the time point S2, but this neutral state is not necessarily maintained, and the pedal at the end of normal sewing is not necessarily required. This operation may be continuously shifted from the depressed state to the depressed state. In this case, when passing through the neutral position during the transition process, neither the depression signal 21a nor the return signal 21b is output, and the control unit 8 uses the no-signal state as a trigger as described above. After the needles 2a and 2b are raised to the vicinity of the top dead center and the looper 1 is moved leftward, the fraying prevention operation is started.

  Further, in the time chart of FIG. 15, the pedal return operation at the time of S2 is to be continued during the execution of the fraying prevention operation described below. It is not necessary to continue until the operation is completed, and the fraying prevention operation is continuously performed by the operation of the control unit 8 even after the input of the stepping signal 21b is stopped.

  FIG. 16 shows the state of the needles 2a and 2b, the looper 1, the thread hook 3 and the looper thread holder 6 at the start of the fraying prevention operation. The needles 2a and 2b are in a state where the needles 2a and 2b are pulled out above the sewing fabric in which the stitches M of the double ring stitch are formed by the two needle threads 20a and 20b and the looper thread 10. The looper 1 moves to the left under the sewing fabric and is in a state where the needle thread loops 20a2 and 20b2 formed by the needles 2a and 2b are captured. When the needle threads 20a, 20b and the looper thread 10 are cut in this state, a general sewing end portion that is likely to fray is formed as shown in FIG.

  After the fraying stop operation is started, the control unit 8 first gives an operation command to the output-side yarn operation cylinder 32 at the time of S4 in FIG. As a result, the thread operating cylinder 32 moves from the extended state shown in FIG. 5 to the contracted state shown in FIG. 6 so that the stopper member 14 is driven and moved to the right. It swings about the support shaft 30 via the connecting rod 35 and moves from the standby position to the thread hooking position. At this time, the hook portion 3 b at the tip of the thread hook 3 hooks one needle thread loop 20 a 1, and the swing lever 9 in the stopper mechanism swings clockwise around the support shaft 90 by the biasing force of the spring 96. Then, the engaging claw 9a at the tip is in a state that can be engaged with a part of the stopper member 14.

  Immediately thereafter, the control unit 8 gives an operation command to the yarn operation cylinder 32, and the yarn operation cylinder 32 is slightly extended from the state shown in FIG. 6 to the state shown in FIG. Driven to the left. When the yarn operating cylinder 32 is extended by a small amount, the engaging claw 9 a at the tip of the swing lever 9 is engaged with a part of the stopper member 14. As a result, the leftward driving movement of the stopper member 14 is temporarily stopped. In the state where the leftward movement of the stopper member 14 is temporarily stopped as described above, as shown in FIG. 17, the thread hook 3 is connected to the standby position and the thread hook position via the connecting rod 35. The hook portion 3b at the tip holds the needle thread loop 20a2 at the holding position, and the looper yarn holder 6 advances to the front side of the looper 1 and moves to the tip looper. The yarn receiver 6a holds the looper yarn 10 in front of the needle drop position A on the left side.

  After stopping the movement of the yarn hook 3 and the looper yarn holder 6 at the respective positions as described above, the control unit 8 issues an operation command to the sewing machine motor 80 and the looper yarn suppressing mechanism 84 at the time of S5 in FIG. give. This operation command is given with reference to the needle position signal 22 until the needles 2a and 2b descend and then rise to the position near the top dead center again. As a result, a sewing operation for one stitch is performed on the sewing fabric. The sewing for one stitch is executed under a feed amount smaller than that during normal sewing by the operation of the feed reduction mechanism 83. Further, the sewing for one stitch is executed in a state where the feeding of the looper thread 10 to the looper 1 is suppressed by the operation of the looper thread suppression mechanism 84. As a result, tightening of the looper thread 10 at the end of sewing is improved, and the fraying prevention effect described later can be enhanced.

  As shown in FIG. 17, the thread hook 3 and the looper thread holder 6 hold the needle threads 20a and 20b and the looper thread 10, and the sewing material feed movement is completed, so that the needles 2a and 2b are threaded. The needle thread loop 20a2 is held, and the process continues until the needle thread loop 20a2 is captured. At this time, the looper yarn 10 held by the looper yarn holder 6 is positioned so as to cross the front side of the left needle 2a as shown in FIG. Accordingly, the left needle 2a does not catch the looper yarn 10, and the looper yarn 10 is only caught on the rear side of the looper 1 by the right needle 2b.

  The control unit 8 gives an operation command to the stopper cylinder 42 of the stopper mechanism at the timing when the left needle 2a catches the needle thread loop 20a2, that is, immediately after S6 in FIG. Accordingly, the output rod 41 is driven to be pushed leftward. As a result, as shown in FIG. 8, the swing lever 9 is swung counterclockwise against the swing biasing force of the spring 96, and the engaging claw 9a at the tip of the swing lever 9 is moved. The engagement is released from a part of the stopper member 14, and the temporary stop of the stopper member 14 is released. By releasing the stop with respect to the stopper member 14 as described above, the yarn operation cylinder 32 is extended to the maximum extent at the time of S6. As a result, as shown in FIG. 18, the thread hook 3 and the looper thread holder 6 swing around the support shaft 30 via the stopper member 14 and the connecting rod 35, and return from the holding position to the standby position. Then, the holding of the needle thread loop 20a2 and the looper thread 10 is released.

  Then, the looper 1 moves backward as the needles 2a and 2b descend, and comes out of the captured needle thread loop 20a2. As shown in FIG. 19, when the looper 1 is pulled out, the right needle 2b is in a state of capturing the looper thread 10 in the same manner as in normal sewing, while the left needle 2a is in the left needle thread loop 20a2. It will be in the state where was captured.

  In this state, the looper 1 turns to the left and the hands 2a and 2b turn upward. As shown in FIG. 20, the looper 1 moving leftward catches the needle thread loops 20a2 and 20b2, and the ascending needles 2a and 2b come out above the sewing fabric. As a result, the needle thread 20a captured by the looper 1 is looped by the so-called own thread looping, in which the needle thread loop 20a2 captured earlier is looped by the needle thread 20a.

  After the sewing operation for one stitch, the needles 2a and 2b are raised to the vicinity of the top dead center, and the looper 1 is finished in the vicinity of the leftward end. Thereafter, the control unit 8 stops the operation of the feed reduction mechanism 83 at the time of S7 in FIG. 15, and waits for this state until the thread trimming signal 23 is given. Then, when the thread trimming signal 23 is given at the time of S8 in FIG. 15, an operation command is given to the thread trimming air cylinder 48 of the thread trimming device 5 to cause the thread trimming air cylinder 48 to perform a predetermined operation. As a result, the thread trimmer 5 is moved to the advance position P1, which is an external position closer to one side of the needle drop positions A and A, as shown in FIG. Thereafter, this thread trimming operation, in which the thread trimming operation is performed, will be described in detail below based on FIG.

  First, as shown in FIG. 21A, after the thread trimming device 5 is moved to the advance position P1, which is an external position closer to one side of the needle drop position, at the end of sewing, as shown in FIG. 21B. In addition, only the movable knife 50 is moved forward (in the left direction) in the direction of the arrow x from the advance position P1 toward the external position closer to the other side of the needle drop position. During the forward drive movement, the blade portion 50e of the movable knife 50 is sequentially pressed against the right needle thread portion 20b1 and the left needle thread portion 20a1 projecting to the back side of the sewing fabric W, and these right and left Each needle thread portion 20b1, 20a1 is cut and cut at the needle drop position or near the needle drop position. By this cutting, the right and left needle thread portions 20b1 and 20a1 each have a short thread remaining length from the back surface of the sewing fabric W to the passing position of the blade portion 50e of the movable knife 50.

  Then, as shown in FIG. 21 (c), the looper yarn portion 10 in which the looper yarn catching portion 50 a on the distal end side of the movable knife 50 is stretched between the vicinity of the distal end of the looper 1 and the back surface side of the sewing fabric W. Immediately after the movement, the moving direction of the movable knife 50 is reversed. Subsequently, as shown in FIG. 21 (d), the movable knife 50 is moved backward (in the right direction) in the direction of the arrow y from the external position near the other side of the needle drop position toward the advance position P1. During this backward drive movement, the looper thread portion 10a protruding to the back side of the sewing fabric W is hooked and captured by the looper thread capturing portion 50a. As the movable knife 50 is further driven backward in the direction of the arrow y, as shown in FIG. 21 (e), the looper yarn portion 10a captured by the looper yarn capturing portion 50a is moved to the capturing portion. It is cut by sliding contact between 50a and the blade edge 51e of the fixed knife 51. At the time of this cutting, the blade edge 51e of the fixed knife 51 is positioned closest to the vertical movement path of the right needle 2b as shown in FIG. The length of the looper thread portion 10a remaining on the back surface of the sewing fabric W after cutting is also shortened.

  Thereafter, as shown in FIG. 21 (f), the needles 2 a and 2 b move above the needle plate 12, and the end of the looper thread 10 held by the looper 1 is moved between the movable knife 50 and the looper thread pinching member 52. And elastically sandwiched between the two.

  The looper yarn suppressing mechanism 84 continues to operate until the above-described thread trimming operation is completed, and applies a predetermined tension to the looper yarn 10 extending from the tip of the looper 1 to the sewing fabric. Thereby, the looper thread | yarn capture | acquisition part 50a of the front-end | tip of the movable knife 50 can capture | acquire and cut | disconnect the looper thread | yarn 10 without a looseness reliably.

  After the above-described yarn cutting operation is completed, the yarn cutting device 5 is moved to the retracted position P2 as shown in FIGS. 10A and 10B via the reciprocating drive moving mechanism 70 to prevent the looper 1 from moving. The sewing machine waits for the next sewing in such an inclined posture. On the other hand, the control unit 8 waits until the needle thread wiping signal 24 is input. When the needle thread wiping signal 24 is input at the time of S9 in FIG. 10, an operation command is output to the air wiper 82 to output the air wiper 82. To work. The air wiper 82 blows out air and jumps up the cut ends of the needle threads 20a and 20b continuous with the needles 2a and 2b. Thereafter, the control unit 8 outputs an operation command to the presser foot cylinder 81 at the time of S10 in FIG. 15 to operate the presser foot cylinder 81, and raises the presser foot to end a series of fraying prevention operations.

In the sewing operation for one stitch for preventing fraying as described above, as shown in FIG.
The looper thread 10 passes through the right needle thread loop 20b2 formed on the back surface of the sewing fabric W at the end of the stitch M, and is pulled out to the back surface of the sewing fabric W during the sewing operation for one stitch for preventing fraying. Is turned back in front of the needle thread 20b, drawn again through the last needle thread loop 20b2 on the right side, and cut.

  On the other hand, the left needle thread portion 20a1 that slips out to the back surface of the sewing fabric W during the sewing operation for one stitch to prevent fraying is the last formed on the back surface of the sewing fabric W following the end of normal sewing. The needle thread loop 20a2 is passed through, and the final needle thread loop 20a2 is looped by itself to form a stitch M of a single ring stitch. Accordingly, the looper thread 10 is firmly held by the needle thread 20a and the final needle thread loop 20b2, and as shown in FIG. 22, the needle thread loop formed once before the left final needle thread loop 20b2. It is restrained to the state spanned between 20c. This constraint is maintained regardless of the direction of the force applied to the looper thread portion 10a, so that fraying peculiar to the stitch M of the double chain stitch is prevented.

  Further, in the sewing operation for one stitch for preventing fraying, since the feed amount of the sewing fabric by the feed dog in the feed reduction mechanism 83 is smaller than the feed amount at the time of normal sewing, as shown in FIG. The stitch pitch P by the other yarn looping before the own yarn looping is smaller than the stitch pitch P0 by the previous yarn looping. As a result, the presser of the looper thread portion 10a between the left needle thread 20a and the left final needle thread loop 20a2 is strengthened, and the retaining resistance is increased. Accordingly, when the state shown in FIG. 22 is reached, fraying of the stitches M of the double chain stitch is accompanied by a decrease in the pitch P of the stitches by the own yarn looping portion and the other yarn looping before the own yarn looping. This can be reliably prevented by a synergistic effect with the increase in the retaining resistance of the looper yarn 10.

  As for the feed with a small feed amount by the feed reduction mechanism 83, the stage before the sewing operation for one stitch for fraying prevention, specifically, the needle thread loop 20a2 by the thread hook 3 is connected to the needle 2a. It may be started from one and a half stitches before the position where the looper 1 is advanced from the lowering position (at the time of S3 in FIG. 15). In this case, the stitch pitch due to the other yarn looping before the own yarn looping is also smaller than the stitch pitch P due to the other yarn looping before that, so that the resistance of the looper yarn 10a to be retained is further increased. Thus, fraying prevention of the seam M can be further ensured.

  Further, in the series of yarn cutting operations described in FIG. 21, as shown in FIG. 21B, only the movable knife 50 moves forward (moves left) in the direction of the arrow x to move the blade of the movable knife 50. When the right and left needle thread sections 20b1 and 20a1 are sequentially pushed and cut by the section 50e, the needle thread presser device 55 is operated to press the needle threads 20b and 20a, so that a constant tension is applied to the needle thread sections 20b1 and 20a1 at the time of cutting. Thus, the needle thread portions 20b1 and 20a1 can be cut and cut reliably and sharply at or near the needle drop positions A and A.

  As described above, according to the thread trimming device 5 of the double chain stitch sewing machine according to the first embodiment, after the predetermined sewing operation (after the end of sewing), the movable knife 50 is externally located closer to one side of the needle drop position. The needle 5e of the movable knife 50 is pressed against the right and left needle thread portions 20b1 and 20a1 projecting toward the back side of the sewing fabric W by moving in an outward drive from the position toward the outer side closer to the other side. Since the thread portions 20b1 and 20a1 are cut and cut at the needle drop position A, A or near the needle drop position, the fraying prevention effect by the self-looping of the needle thread portions 20b1 and 20a1 on the back surface of the sewing fabric W is not impaired. It is possible to automatically cut the length to a short remaining length that does not protrude greatly from the seam M of the sewing fabric W. As a result, the yarn does not fray from the stitches after fraying prevention, and the finish and appearance of the sewn product can be improved as a whole.

  Further, when the movable knife 50 is retrogradely driven from the external position near the other side of the needle drop positions A and A toward the external position near the one side, the looper thread catching portion 50a formed on the movable knife 50 is sewn into the sewing fabric. After hooking and catching the looper yarn portion 10a protruding to the back side of W, the looper yarn portion 10a is brought into the needle drop position within a range in which the blade edge portion 51e at the tip does not enter the double up and down movement path of the right needle 2b. Since the fixed knife 51 and the looper thread catching section 50a that are positioned closest to each other are cut by sliding contact, the remaining length of the looper thread section 10a on the back surface of the sewing fabric W also protrudes greatly from the stitches M. Automatic cutting can be performed so that the remaining length is as short as possible.

Therefore, at the end of sewing, for example, by using hand-kneading or the like, the thread portions 20b1, 20a1, 10a on the back side of the sewn fabric W are cut so that the remaining thread length is shortened, and variation is caused. The manual work that tends to occur is completely unnecessary. Therefore, a combination of the fact that manual work for cutting the yarn is not necessary and the fact that the above-mentioned fraying prevention by the own yarn looping eliminates the need for a separate process such as tacking or the like makes it possible to produce a large number of sewn products one after another. In the case of continuous production, the sewing work efficiency (productivity) can be significantly improved. In addition, the sewing fabric may be damaged by hand-kneading, etc., or it may be cut so that the remaining thread length becomes shorter than necessary due to variations in the cutting position. It is also possible to prevent the thread from fraying from the stitches, and it is possible to realize improvement in the finish and appearance of the sewn product as a whole.

Next, a horizontal cylindrical double chain stitch sewing machine according to a second embodiment of the present invention will be described.
As shown in FIG. 23, the horizontal cylindrical double chain stitch sewing machine according to the second embodiment is configured so that the blade portion 50e of the movable knife 50 in the thread trimmer 5 is substantially reversely inclined as in the case of the first embodiment. In the point which formed in 1st Embodiment, it differs from 1st embodiment, and a structure other than that is completely the same as 1st embodiment. Therefore, descriptions and specific illustrations are omitted for configurations other than the above-described configuration (the shape of the blade portion 50e of the movable knife 50) that is different from the first embodiment.

  In the horizontal cylindrical double chain stitch sewing machine of the second embodiment, the movable knife 50 in the thread trimming device 5 is shifted from the external position closer to the other side (left side) of the needle drop positions A and A to the position closer to one side (right side). When the backward drive is moved (when moving from the state corresponding to FIG. 21C to the state corresponding to FIG. 21D), the blade portion 50e protrudes toward the back side of the sewing fabric W. The needle thread portions 20a1 and 20b1 are sequentially brought into contact with the left and right needle thread portions 20a1 and 20b1, and the needle thread portions 20a1 and 20b1 are cut and cut at or near the needle drop positions A and A.

In the case of the second embodiment, as in the case of the first embodiment, the needle thread portions 20a1 and 20b1 and the looper yarn portion 10a that protrude from the back surface of the sewing fabric W are prevented from fraying by the own yarn looping. It is possible to automatically cut the remaining length so as not to be damaged and to a length that does not protrude significantly from the stitches M. As a result, like the first embodiment, it is possible to achieve a significant improvement in the sewing work efficiency (productivity) in the case of continuous production after another large amounts of sewn products, damage the sewing cloth such as by viewing Te鋏 In addition, it is possible to improve the finish and appearance of the sewn product as a whole without causing the yarn remaining length to impair the fraying prevention effect of the own yarn looping due to variations in the cutting position.

  In each of the above embodiments, the blade part 50e of the movable knife 50 is described as having a shape that cuts or cuts the needle thread parts 20a1 and 20b1 protruding from the back surface of the sewing fabric W. However, when the movable knife 50 moves forward or moves backward, the blade portion 50e moves in contact with the side surfaces of the needle thread portions 20a1 and 20b1, thereby moving the needle thread portions 20a1 and 20b1 from the side surfaces. You may form in the shape which cuts and cuts.

  In each of the above-described embodiments, the looper thread holding body 6 is configured to be capable of moving toward and away from the looper 1 integrally with the thread hook 3 in the needle thread holding mechanism. The looper thread holding body 6 may be configured to be capable of moving toward and away from the looper 1 separately from the thread hook 3 in the needle thread holding mechanism. Furthermore, the installation of the looper yarn holder 6 is not essential.

  In the first embodiment, the looper yarn holder 6 is advanced to the front side of the looper 1, and the looper yarn receiving portion 6a at the tip holds the looper yarn 10 in front of the needle drop positions A and A. However, the looper yarn receiving portion 6a at the front end may hold the looper yarn 10 at the rear portion of the needle drop positions A and A.

  Further, the needle thread presser device 55 described in the first embodiment is effective for ensuring the cutting of the needle thread portions 20a1 and 20b1, but the blade portion 50e of the movable knife 50 is sharp. The installation may be omitted.

  Furthermore, in each of the above embodiments, the needle plate base 11 to which the anti-fraying device H is attached adopts a structure that is divided into a left needle plate base part 11L and a right needle plate base part 11R, thereby Although the description has been made of the fraying prevention device H that can improve the assembly workability and the ease of maintenance with respect to the sewing machine bed portion B, as the needle plate base 11 in the fraying prevention device H, FIG. As shown in FIG. 26, it may be configured as a single body that is long on the left and right.

  Furthermore, in each of the above embodiments, a two-needle horizontal cylindrical double chain stitch sewing machine is applied, but a single needle horizontal cylindrical double chain stitch sewing machine or a flat bed type double chain stitch sewing machine is used. You may apply to a sewing machine.

DESCRIPTION OF SYMBOLS 1 Looper 2a, 2b Needle 3 Thread hook 4 Stopper member 6 Looper thread holding body 8 Control part 10 Looper thread 12 Needle plate 20a, 20b Needle thread 20a1, 20b1 Needle thread part 20a2, 20b2 Needle thread loop 50 Movable knife 50a Looper thread Trapping part 50e Blade part 51 Fixed knife 51e Blade edge part 52 Looper thread pinching member 55 Needle thread presser 83 Feed reduction mechanism 84 Looper thread suppression mechanism A Needle drop position B Sewing bed part M Double chain stitch seam H Fray stopper Equipment W Sewing fabric

Claims (5)

A needle thread loop formed by one or more needles that move up and down while holding the needle thread is formed by the advancement of a looper that can move forward and backward in a direction substantially perpendicular to the vertical movement path of the needle, A double chain stitch method for looping the needle thread loop with a looper thread held by the looper to form a double chain stitch on a sewing fabric that is fed and moved on the needle plate,
After finishing the normal sewing with the looper in the advanced state, the needle thread loop captured by the looper is held at the advanced end side of the looper from the lowered position of the needle, and the looper thread is lowered by the needle. After being positioned in front of the position, the feeding of the looper thread to the looper is suppressed, and this state is maintained until the needle descends through the needle thread loop captured by the looper. The needle thread loop is held by the needle thread held by the needle by causing the sewing operation to be performed for at least one stitch including releasing the position holding of the thread loop and lowering the needle through the needle thread loop. Loop the self thread to prevent fraying of the stitches of the double chain stitch,
After that, the reciprocating drive movement between the both positions of the movable knife capable of reciprocating movement between the external position near one side of the needle drop position on the needle plate and the position near the other side of the needle drop position is performed. Of these, when the movable knife is moved forward from the position near one side of the needle drop position toward the external position near the other side, or the movable knife moves from the external position near the other side toward the one side position. Te when being moved inbound drive, the cutting press-cutting the blade portion formed in the movable knife needle thread portion protruding on the back surface side in the vicinity of the stitch point or needle drop position of the sewing cloth or sawing cut And
Subsequently, when the movable knife moves backward from the other side position of the needle drop position toward the outer side position, the sewing cloth is formed by the looper thread catching portion formed on the movable knife. The looper yarn portion protruding to the back side of the needle is hooked and transferred to the blade edge portion of a fixed knife arranged close to the needle drop portion without entering the vertical movement path of the needle to catch the looper yarn. Cutting the looper thread portion by sliding contact between the portion and the edge of the fixed knife,
And the end of the cut looper thread is elastically pinched and held between the movable knife and a looper thread pinching member disposed at the lower part of the movable knife, and waits for the next sewing. Double chain stitching method to do. The sewing operation for the at least one stitch for the self-looping is performed in a state in which the feed movement of the sewing fabric is stopped or a feed movement with a feed movement amount smaller than the feed movement amount of the sewing fabric during normal sewing. The double chain stitch method according to claim 1 , which is carried out in ( 1 ). One or a plurality of needles that move up and down while holding the needle thread, and can move forward and backward in a direction substantially perpendicular to the vertical movement path of the needle while holding the looper thread. A looper that captures the needle thread loop formed on the needle plate, and a reciprocating drive movement between an external position closer to one side of the needle drop position on the needle plate and a position closer to the other side of the needle drop position. A double chain stitch sewing machine that forms a stitch of double chain stitch on a sewing fabric that is fed and moved on the needle plate by looping the other thread with the looper thread held by the looper. Because
The movable knife and the fixed knife which cut the needle thread part and the looper thread part protruding to the back side of the sewing fabric after the formation of the seam of the double chain stitch, and the end of the looper thread after cutting are connected to the movable knife. In a double chain stitch sewing machine having a thread trimming device composed of a looper thread pinching member that is elastically pinched and held between them,
A needle thread holding mechanism capable of moving toward and away from the looper, and holding the needle thread loop captured by the looper during the approaching operation on the advance end side of the looper from the lowered position of the needle;
A looper thread holding body capable of moving toward and away from the looper, and holding a looper thread extending from the looper to the sewing fabric during the approaching operation at a position on the front side of the lowering position of the needle;
A looper yarn suppressing mechanism that suppresses sending of the looper yarn to the looper;
A control unit that controls the contact and separation operations of the needle thread holding mechanism and the looper thread holding body in association with the operations of the needle and the looper, and the feed movement operation of the sewing fabric,
The control unit sets the looper to the advanced position, sets the needle to the raised position, and after completing normal sewing, moves the needle thread holding mechanism closer to the needle thread loop than the lower position of the needle. The position of the looper thread holding body is moved closer to the looper to move the looper thread to the front side of the lowering position of the needle, and then the operation of the looper thread restraining mechanism is started. The looper thread is prevented from being fed to the looper, and this state is maintained until the needle descends through the needle thread loop captured by the looper, and then the position holding of the needle thread loop is released. And performing a sewing operation for at least one stitch including the lowering and raising of the needle, the advance / retreat operation of the looper, and the feeding operation of the sewing fabric, and the needle descending through the needle thread loop. The Rukoto has the needle is configured to perform fray stop operation of the stitch by the needle thread by Jiito looping the needle thread loop double chain stitch holding,
The movable knife in the thread cutting device, the movable knife of the reciprocating movement the movable knife after the fray stop action spans between the other side nearer position to the one side toward the outside position of the needle drop position When the forward movement is moved from the position closer to one side of the needle drop position toward the outer position closer to the other side, or the movable knife moves backward from the outer position closer to the other side toward the position closer to the one side. when it is, together with the blade portion of the needle thread portion for press-away cutting or sawing cut in the vicinity of the needle drop position or needle position projecting to the back side of the sewing cloth is formed, the movable knife is the A looper yarn catching portion is formed that hooks and catches a looper yarn portion that protrudes on the back side of the sewing fabric when moved backward from the other side of the needle drop position toward the outer side of the one side. And The fixed knife and looper thread scissors member in the thread cutting device is arranged at a position close to the needle portion to the extent that their tip from entering the up-down movement path of the needle,
When the movable knife is moved backward from the other side position of the needle drop position toward the outer side position, the movable knife is captured by the looper thread trapping section and transferred to the tip of the fixed knife. The looper yarn portion is cut by sliding contact between the looper yarn catching portion and a fixed knife, and the end portion of the cut looper yarn is elastically sandwiched between the movable knife and the looper yarn clamping member. A double chain stitch sewing machine characterized by being held and waiting for the next sewing. The control unit is configured to perform a sewing operation for at least one stitch for the looping of the own thread in a state in which the feeding movement of the sewing fabric is stopped, or a feeding movement amount smaller than a feeding movement amount of the sewing fabric during normal sewing. The double chain stitch sewing machine according to claim 3 , wherein the sewing machine is configured to be implemented under a feed movement. The double chain stitch sewing according to claim 3 , further comprising a needle thread presser device that presses and holds the needle thread at an upper part of the needle plate when the needle thread part is cut and cut by the blade part of the movable knife. sewing machine.

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