TWI523984B - The stray line of the stitch prevents the method and the stitching of the stitching device - Google Patents

Description

Fringe preventing method of stitches and fray preventing device for stitches

The present invention relates to a method for preventing fraying of a fray that prevents a stitch occurring at a sewing end portion from being used in a stitch of a double-line lock stitch formed by a sewing machine such as a double-thread lock sewing machine or a flat sewing machine. And a fray prevention device for carrying out the method.

The double-line lock stitch sewing machine includes a plurality of needles that hold the needle thread to ascend and descend, and a looper that keeps the looper thread moving forward and backward in the direction in which the needles are arranged. A plurality of needles are lowered through the sewing material on the needle plate, and are pulled out from the sewing material to rise. The looper advances and retreats under the needle plate in conjunction with the ascending and descending of the needle, and catches the loop (needle loop) of the needle thread held by the plurality of needles that are rising during entry. A plurality of needles are lowered through the sewing material that feeds the movement, and the looper thread held by the looper in the retraction is captured.

The two-line lock stitch sewing machine forms stitches on the sewing material by repeating the above actions. By such an action, in the needle thread loop formed by the needle threads 6, 6 on the back side of the sewing material, the looper thread 7 is wound in a form of interconnection to form a double-line stitching stitch as shown in Fig. 22A. . In such a stitch, there is a problem that the final needle thread formed by the looper thread 7 from the needle thread 6 and 6 is pulled when the end portion of the looper thread 7 cut at the sewing end is pulled as shown by an arrow in the figure. The wire loops 6a, 6b are disengaged, and such a detachment gradually transitions toward the sewing start end side to cause fraying.

This problem also occurs in the stitches of the double-line lock stitch formed by three or more needle threads and looper threads, and also in all the sewing machines that form the double-line stitch stitches such as the flat seam sewing machine. occur.

A method for preventing such a fray from occurring and an apparatus for carrying out the method have been proposed in the past. One of them is the fray prevention method and apparatus proposed by the present applicant (refer to Japanese Patent No. 2879399). In the fray prevention method, a hook thread hook that is held by the looper thread of the needle thread loop at the entrance end of the looper due to the entry of the looper is provided, and at the end of the usual sewing, the looper thread is hooked at When the needle is raised and the looper enters, the looper thread is held, and in this state, the stitching operation is performed after one stitching operation, and the looper thread is cut.

According to this method, the looper thread 7 held by the hook thread hook is wound in the form of an interconnection in the final needle thread loops 6a, 6b formed by the needle threads 6, 6 to form a stitch of the form shown in Fig. 22B. The looper thread 7 wound in this manner does not come out of the final needle thread loops 6a, 6b even if the end portions thereof are pulled as indicated by the arrow, so that the fray of the stitches can be prevented from occurring.

The fray prevention method proposed in Japanese Patent No. 2879399, as described above, is an excellent method capable of effectively preventing occurrence of a characteristic fray in a stitch of a double-line lock stitch. However, in the stitch shown in Fig. 22, the end portion of the looper thread 7 may come out of the final needle thread loops 6a, 6b when the force in the direction indicated by the white arrow in the figure is applied. There is a problem in that the looper thread 7 which is released from the final needle thread loops 6a and 6b is sequentially taken out from the sewing start end side in the same manner as the stitch of the general double-thread lock stitch, and the fray line is developed to the line. Trace the whole.

For example, in the sewing of a thin sewing material or a soft sewing material, in the case where the tension applied to the needle threads 6, 6 and the looper thread 7 is reduced in order to obtain a good finished state, since the needle thread loops 6a, 6b are bent The above problem is caused by insufficient fastening of the needle thread 7.

An object of the present invention is to provide a novel fray prevention method which is effective in preventing a fray which is unique to a stitch in which double-line lock stitching is generated, and which is hardly affected by the tension applied to the needle thread, and a fray prevention method for performing the fray prevention Method of fray prevention device.

A method for preventing a fray of a stitch of the first invention for preventing a fray of a stitch of a double-line lock stitch, wherein the double-line lock stitch passes through a needle thread formed by holding a plurality of needles that move downward on the needle thread under the needle plate The ring is captured by a looper that enters in the direction in which the needles are arranged, and the needle thread is held by the looper to form the needle thread, and is formed on the seam on which the feed movement is performed on the needle plate. : at the end of the normal sewing, the looper is brought into an entry state, and at least one of the plurality of needle thread loops captured by the looper including the needle loop of the entry side of the looper is in the looper The rear side is held, and at least one stitching operation is performed while maintaining the state as described above, so that the needle that has descended to the held needle thread loop passes, and the needle thread loop is self-joined by the needle thread held by the needle.

According to a second aspect of the present invention, in the method of preventing the fray of the stitch, the sewing operation of the first invention is performed by stopping the feeding of the sewing material or by making the feeding distance of the sewing material smaller than that during normal sewing.

A fray preventing device for a stitch according to a third aspect of the present invention is provided in a sewing machine for preventing a fray of a stitch of a double-line lock stitch, the sewing machine comprising a plurality of needles for holding the needle thread to move downward, and a needle holding the hook thread at the needle a looper that advances and retreats in the direction of alignment, captures a needle thread loop formed by the plurality of needles under the needle plate by entering the looper, and interconnects the needle thread by the looper thread held by the looper, and the double thread The stitching stitch is formed on the sewing material for feeding movement on the needle board, and is characterized in that: a needle thread holding mechanism is provided on the rear side of the curved needle, and the approaching and leaving motion is performed with respect to the curved needle, and the approaching action is performed. And capturing at least one of the plurality of needle thread loops captured by the looper at least one of the needle loops located on the entry side of the looper; and controlling the movement of the needle and the looper And controlling the approaching and separating operation of the needle thread holding mechanism in association with the feeding operation of the sewing material, wherein the control unit causes the bending needle to be in the entering position and the needle to be in the rising position After the sewing is normally performed, the needle thread holding mechanism is moved to hold the needle thread loop, and the above-described state is maintained, and at least one drop of the needle is performed in accordance with the advancement and retreat operation of the looper and the feeding operation of the sewing material. And a sewing action that increases the amount of a needle.

In the fray line preventing device of the stitch according to the fourth aspect of the invention, the control unit performs the sewing operation of the one-a-point amount by the feeding distance of the feeding operation of the sewing material to zero or less than the normal sewing time.

In the fray preventing method of the stitch of the first invention and the fray preventing device of the stitch of the third invention, the looper loop caught by the looper is held at the rear side of the looper which is in the entering state at the end of sewing, In this state, at least one stitching operation is performed, and the held needle thread loop is self-joined by the needle thread held by the needle lowered to the position. Therefore, by pressing the looper thread with the self-joining portion of the needle thread, it is possible to prevent the looper thread from coming off, and it is possible to reliably prevent the flaw of the stitch from occurring in the stage of occurrence. The pressing of the looper by the self-joining portion of the needle thread can be favorably formed even when the tension applied to the needle thread is small, and the occurrence of the fray can be effectively prevented.

In the fray preventing method of the stitch of the second invention and the fray preventing device for the stitch of the fourth invention, the feeding of the sewing material is stopped or the feeding distance of the sewing material is small, and the sewing operation for fray prevention is performed. . Therefore, the self-joining portion formed by the needle thread is densified, and the pressing of the looper thread is strengthened, and the occurrence of the fray line starting from the escape of the looper thread can be reliably prevented.

A floss preventing device for a stitch according to a fifth aspect of the present invention, characterized in that the thread holding mechanism includes: a hook hook and a limit lever, disposed under the needle plate and swinging in a plane substantially parallel to the needle plate; a hook actuator for swinging the hook hook from a standby position away from the looper to a hook line position adjacent to the looper; and a limit actuator for causing the limit lever to move away from the swing region of the hook hook The retracted position is swung to a restricted position in contact with a portion of the hook line hook, and the control portion selectively controls the hook actuator and the limit actuator to be in contact with the limit rod at the hanging line position The holding position between the standby positions maintains the sewing thread loop caught by the hook hook at the hanging position, and the sewing operation of the one stitch is performed in the state as described above.

In the fray preventing device of the stitch of the fifth invention, the thread hook is held by the hook hook and the limit lever that swing in the plane parallel to the needle plate. Therefore, the needle thread can be held in a simple structure that can be disposed in a limited space under the needle plate, and the hook hook and the limit lever can be swung between the two positions, respectively, and the respective actuators and the same The structure of the control unit is also simplified, and the occurrence of the fray of the stitch can be prevented with a simple structure.

A floss preventing device for a stitch according to a sixth aspect of the present invention, characterized in that the thread holding mechanism includes: a hook hook disposed under the needle plate and swinging in a plane substantially parallel to the needle plate; The position rod is disposed at a position farther from the needle plate than the hook line, and swings in a plane substantially parallel to the needle plate; and connects the hook of the hook and the connecting rod of the swing rod; and the hanging rod is connected by the swing rod a hook hook swinging from a standby position away from the looper to a hook actuator near a hook position of the looper; and swinging the limit lever from a latching position engaged with a portion of the swing lever to leave the card a limit actuator for the retracted position of the position, wherein the control unit selectively controls the hook actuator and the limit actuator, and the engagement between the limit lever and the swing lever is at the hanging position The holding position between the standby positions maintains the sewing thread loop caught by the hook hook at the hanging position, and the sewing operation of the one stitch is performed in the state as described above.

In the fray preventing device for a stitch of the sixth invention, the thread is held by the associated action of the hook hook, the swing lever, and the limit lever that swing in the plane parallel to the needle plate. Therefore, the holding of the needle thread can be achieved with a simple structure that can be arranged in a limited space under the needle plate. Further, the swing lever and the limit lever are disposed at positions apart from the needle plate, and only the hook hook is disposed in the vicinity of the needle plate. Therefore, it can be applied to a sewing machine in which the lower space of the needle plate such as a sewing machine having a cylindrical base is more limited.

The objects and novel features of the invention will be apparent from the description and appended claims.

The invention is described in detail below based on the drawings showing preferred embodiments. 1 to 3 are plan views schematically showing the configuration of the strand fray preventing device of the first embodiment. The device shown in the drawings can be equipped with a sewing machine that forms a double-line lock stitch such as a double-thread lock sewing machine or a flat sewing machine. In the following description, "left, right" and "front and back" indicated by arrows in Fig. 1 are used.

The sewing machine has a looper 1 and two needles 2 and 2 (see Figs. 6 to 14). The needles 2, 2 are raised and lowered by the action of the needle bar drive mechanism. A and A in Figs. 1 to 3 indicate the lowered positions of the needles 2 and 2 (needle drop position). The needle drop positions A and A are set at substantially the center of the needle board P at intervals in the left-right direction.

The looper 1 moves forward and backward (leftward and rightward) in the direction in which the needles 2, 2 (needle drop positions A, A) are arranged by the action of the looper drive mechanism. In Fig. 1, the looper 1 in the leftward position is indicated by a solid line, and the looper 1 in a rightward retracted position is indicated by a broken line. The front end of the looper 1 in the leftward position extends beyond the needle drop positions A, A, and the front end of the looper 1 in the right retracted position is located away from the right side of the needle drop positions A, A.

The sewing machine sews the sewing material (not shown) on the needle board P by the raising and lowering movement of the needles 2, 2 and the leftward and rightward movements of the looper 1. The sewing material is pressed by the presser foot (not shown) on the needle board P, and the feed operation is performed to the rear (the direction indicated by the white arrow in Fig. 1) by the operation of the feeding mechanism provided inside the sewing machine seat. The feeding mechanism includes a feeding tooth that repeats an operation of projecting rearwardly on the needle plate P and hiding it under the needle plate P to return to the front. The sewing material is applied with a moving force only during the period in which the feeding teeth protrude on the needle board P, and the feeding movement is intermittently performed.

The needle bar drive mechanism, the looper drive mechanism, and the feed mechanism are well-known mechanisms that operate in synchronization with each other by the drive from the main shaft of the sewing machine. The needles 2 and 2 hold the needle wires 6 and 6 (see FIGS. 6 to 14 ), respectively, and the sewing material passes through the sewing material to reach the lower side of the needle plate P while the sewing material has almost stopped the feeding movement, and then is pulled up and pulled out above the sewing material. The looper 1 holds the looper thread 7 (see FIGS. 6 to 14), and is close to the start of the rise of the needles 2 and 2, and catches the loop of the needle threads 6 and 6 formed under the needle plate P. The sewing material moves while the needles 2, 2 are rising. The needles 2 and 2 are lowered by the sewing material after the feed movement, and the looper thread 7 held by the looper 1 in the right retraction is caught. The sewing machine repeats the above actions to form a stitch of a double-line lock stitch on the sewing material.

The sewing machine has a stitch fray preventing device as described above, and includes a hook hook 3 and a limit lever 4. The hook hook 3 is supported by the inside of the sewing machine seat on the rear side of the needle board P so as to be swingable about the support shaft 30 in the up-down direction. The limiter lever 4 is swingably supported around the support shaft 40 disposed in the vertical direction behind the support shaft 30.

The hook hook 3 has a circular arc-shaped curved shape, and is connected to the left front side at the end of the arm 3a extending rearward from the support shaft 30. The front end portion of the hook hook 3 faces the needle drop positions A and A from the left rear side, and the front end portion is provided with a hook portion 3b that protrudes outward, and the base portion of the hook hook 3 (connected portion with the arm 3a) The connecting rod 31 is coupled to the threading solenoid 32. The hanging wire solenoid 32 is a rotating solenoid configured to obtain a rotation output of a predetermined angle by turning on the exciting current. The threaded solenoid 32 is fixed at the right rear position of the hook hook 3 with the output end facing upward. A swing arm 33 is fixed to the output end of the hook solenoid 32. The connecting rod 31 is connected to the intermediate portion of the hook hook 3 and the front end portion of the swing arm 33.

1 shows the degaussing state of the hanging solenoid 32, and FIG. 2 shows the exciting state of the hanging solenoid 32. In the case where the hanging solenoid 32 is in the demagnetized state, the swing arm 33 is located at the swing position of FIG. When the hanging solenoid 32 is excited, the swing arm 33 swings clockwise as indicated by an arrow in Fig. 1 to become the swing position shown in Fig. 2 . The swinging of the swing arm 33 is transmitted to the hook hook 3 via the connecting rod 31. The hook hook 3 swings counterclockwise about the pivot shaft 30 as indicated by an arrow in Fig. 1, and the hook portion 3b of the front end of the hook hook 3 is as As shown in Fig. 2, it is located between the left and right needle drop positions A and A. In this manner, the hook hook 3 responds to the excitation of the hook solenoid 32, swinging from the standby position shown in Fig. 1 to the hook position shown in Fig. 2. The hook solenoid 32 is equivalent to a hook actuator.

The stopper rod 4 is supported by the support shaft 40 and has an arch shape in which the front portion is curved into a concave portion. The base of the stopper rod 4 extending to the right front is coupled to the limit solenoid 42 by a connecting rod 41. The limit solenoid 42 is the same rotary solenoid as the suspension solenoid 32, and the output end is fixed upward at a position away from the right side of the limit lever 4. At the output end of the limit solenoid 42, a swing arm 43 is fixed. The connecting rod 41 is coupled to the base of the stopper rod 4 and the front end portion of the swing arm 43.

FIG. 1 shows the degaussing state of the limit solenoid 42. In the case where the limit member solenoid 42 is in the demagnetized state, the swing arm 43 is located at the swing position of FIG. When the limiter solenoid 42 is excited, the swing arm 43 swings clockwise as indicated by the arrow in FIG. The swing of the swing arm 43 is transmitted to the limit lever 4 via the connecting rod 41, and the limit lever 4 swings clockwise around the support shaft 40 as indicated by an arrow in FIG.

When the limiter solenoid 42 is in the demagnetized state, the front end portion 4a extending to the left front side of the stopper rod 4 overlaps with a part of the hook hook 3 at the standby position as shown in FIG. The hook hook 3 has a step portion 3c that is provided on the front side and raised at a position rearward of the overlapping portion of the stopper rod 4. The front end portion 4a of the stopper rod 4 can overlap the lower position of the hook hook 3 at a position forward of the step 3c. Further, the stopper rod 4 has a step 4b between the support shaft 40 and the base. The step 4b is provided to be raised on the rear side, and as shown in Fig. 1, can be intersected with the connecting rod 31 at a lower position.

When the hook hook 3 is swung to the above-mentioned hanging position, the limit solenoid 42 is in the demagnetized state. The stopper rod 4 is pushed by the hook hook 3 to swing counterclockwise, so that the hook hook 3 can swing. The stopper rod 4 is at a position (restricted position) indicated by a solid line in Fig. 2 after the hook hook 3 is passed. It is also possible to cause the limit solenoid 42 to be excited together with the hanging solenoid 32 when the hook hook 3 is swung to the hanging position, so that the limit lever 4 is moved to the position shown by the chain double-dashed line in FIG. (Retraction position). In this case, the hook hook 3 can swing without any interference to the limit lever 4. The stopper rod 4 is in a restricted position by degaussing the limit solenoid 42 after the end of the hook hook 3 is swung. The front end portion 4a of the stopper rod 4 at the restricting position faces the rear side of the locking portion 3d that protrudes outward in the middle portion of the hook hook 3. The locking portion 3d of the hook hook 3 is provided on the rear side of the step 3c, and is at the same height as the front end portion 4a of the stopper rod 4.

In the state shown in Fig. 2, when the hanging solenoid 32 is demagnetized, the swing arm 33 swings counterclockwise as indicated by the arrow in Fig. 2, and the hook hook 3 swings counterclockwise. Such a swing is restricted by the locking portion 3d of the hook hook 3 being abutted against the front end portion 4a of the stopper rod 4, and the hook hook 3 is stopped at the holding position shown in FIG. At this time, the hook portion 3b at the front end of the hook hook 3 is moved from the hook position (between the left and right needle drop positions A and A) shown in FIG. 2 to the holding position shown in FIG. 3 (needle drop position A on the left side) The rear of the needle 2 of the needle 2 on the left side of the pull tab is held in the position shown in Fig. 3 as will be described later. The hook portion 3b of the hook hook 3 has a chamfered corner portion as shown in the drawing, and prevents damage of the needle thread 6, 6 and the looper thread 7 that are in contact during the movement as described above.

In the state shown in FIG. 3, when the limiter solenoid 42 is excited, as shown by the arrow in FIG. 3, the swing arm 43 swings counterclockwise, and the limit lever 4 swings clockwise. The front end portion 4a of the stopper rod 4 moves to a position indicated by a chain double-dashed line in Fig. 3, and is separated from the locking portion 3d of the hook hook 3. The hook hook 3 is restored to the standby position shown in FIG. 1 because the restriction is released. The limit lever 4 returns to the position shown in FIG. 1 by demagnetizing the limit solenoid 42. The above sewing by the sewing machine is performed in this state. The limit solenoid 42 is equivalent to a limit actuator.

The hook hook 3 is in the standby position, the hanging position, and the holding position by selectively exciting the hanging solenoid 32 and the limiting solenoid 42. In the apparatus of the first embodiment, the hooking hook 3 is operated at the end of the sewing, and the fray preventing method of the present invention is carried out as will be described later.

The sewing machine also includes a thread trimming mechanism 5. The thread trimming mechanism 5 includes a thread trimming hook 50 and a thread cutter 51. The thread trimming hook 50 is supported by the right side of the looper 1 in the right and left direction in the right and left direction. The thread cutter 51 is a flat member that elastically contacts the upper portion of the thread cutter hook 50, and has a blade at an end edge toward the left side.

As shown in FIG. 1, the thread trimming hook 50 is in an initial position in which a part of the tip end protrudes from the blade portion of the thread cutting blade 51. The thread trimming hook 50 includes a first hook portion 52 provided in the vicinity of the front end portion and a second hook portion 53 provided in the middle portion. The first and second hook portions 52 and 53 project rearward, and the protruding position of the second hook portion 53 is larger than the protruding position of the first hook portion 52. In FIG. 1, the first and second hook portions 52, 53 which overlap with the lower position of the thread cutter 51 are shown by broken lines.

The thread trimming hook 50 and the thread cutter 51 are mounted on a common base 54. The susceptor 54 is swingable about the support shaft 54a in the up-and-down direction of the right end portion. A swing lever 55 is coupled to a middle portion of the base 54. The thread trimming hook 50 and the thread cutter 51 are oscillated in response to the swing lever 55 in response to the base 54 and move between the trimming position shown in FIGS. 1 to 3 and the retracted position on the rear side of the trimming position. The front end portion of the thread cutting hook 50 at the thread cutting position is located at the upper right portion of the looper 1. The thread cutting hook 50 and the thread cutter 51 are moved to the retracted position during sewing so as not to hinder the forward and backward movement of the looper 1.

The thread trimming hook 50 has an extension extending to the right of the thread cutter 51, and the extension portion is coupled to one end portion of the thread trimmer 57 by a slider 56 that slides in the left-right direction with the base 54 as a guide. The thread trimming lever 57 is swingable about the support shaft 57a in the vertical direction, and is swung in the left-right direction by the operation of the thread trimmer 58 (see FIG. 4) connected to the other end. This swing occurs in a state where the thread trimming hook 50 and the thread trimming blade 51 are in the trimming position as shown in FIG. 1, and the thread trimming hook 50 performs a rightward backward motion after performing the leftward motion together with the slider 56.

Fig. 4 is a block diagram showing a control system of the sewing machine having the above-described stitch fray prevention device. The control unit 8 of the sewing machine is respectively input with the stepping signal 21a and the stepping signal 21b from the pedal switch 21, the needle position signal 22 which is emitted when the needles 2, 2 are near the top dead center, and the thread trimming as will be described later. Signal 23 and needle removal signal 24.

The output of the control unit 8 is respectively given to the above-mentioned hooking solenoid 32, the limiting solenoid 42 and the trimming actuator 58, and the hooking hook 3 and the limit lever 4 are respectively given to the threading snail by the control unit 8. The operation commands of the conduit 32 and the limit solenoid 42 operate as described above, and the thread cutter hook 50 advances and retracts as described above in accordance with the operation command given to the thread trimmer 58 by the control unit 8.

In addition, the output of the control unit 8 is also given to the sewing machine motor 26, which is a driving source of the sewing machine main shaft, the pressing cylinder 27 that raises and lowers the presser foot for pressing, and the needle thread 6 and 6 which are cut as will be described later. An air wiper 28 and a feed reduction mechanism 29 for adjusting the feed amount of the sewing material. The sewing machine motor 26 is driven or stopped in accordance with an operation command from the control unit 8, and the press cylinder 27, the air brush 28, and the feed reduction mechanism 29 operate in accordance with an operation command from the control unit 8.

The feed reduction mechanism 29 is a known mechanism for reducing the feed amount of the sewing material by changing the operation state of the feed teeth of the feed mechanism. The change of the operation state of the feed tooth is performed, for example, by inclining the operation path of the feed tooth with respect to the needle plate P and shortening the projection time to the needle plate P. Thereby, the time during which the feed tooth applies a moving force to the sewing material becomes short, and the feed amount of the sewing material becomes small.

FIG. 5 is a timing chart showing the operation contents of the control unit 8 for fray prevention. The control unit 8 is a computer having a CPU, a ROM, and a RAM, and is operated in accordance with a series of operations of the CPU of the control program stored in the ROM in accordance with the fray prevention operation of the timing chart of FIG. 6 to 14 are operational explanatory views of the apparatus of the present invention, showing an operation state of the hook hook 3 and the thread trimming hook 50 which are generated during the operation of the control unit 8 in accordance with the timing chart of Fig. 5 .

When the sewing machine using the sewing machine stops the stepping operation of the pedal for driving the sewing machine when the sewing of the sewing material is finished, and then performs the fraying prevention operation, the pedal is stepped back. The pedal switch 21 is attached to the above-described pedal, and outputs a depression signal 21a in the depression operation, and outputs a depression signal 21b when the depression operation is performed.

When the sewing of the sewing material is completed, the control unit 8 returns to the stepping signal 21a and the stepping signal 21b by the pedal switch 21 when the pedal for driving the sewing machine is returned to the neutral state from the stepping state at time S1 in Fig. 5 . In the state of any one of them, the sewing machine motor 26 on the output side is issued with a stop command by referring to the needle position signal 22 given to the input side, and the sewing machine is placed in the state where the needles 2, 2 are near the top dead center and the looper 1 is left. Temporarily stopped.

Then, the control unit 8 waits until the pedal is operated to perform the step-back operation, and performs the step-back operation at the time S2 of FIG. 5, and starts the fray prevention operation described below on the condition that the input side is given the step-back signal 21b. When the pedal switch 21 again inputs the depression signal 21a, the control unit 8 returns to the normal sewing operation. The sewing worker can continue the normal sewing by performing the stepping operation on the pedal again.

In FIG. 5, the neutral state is maintained from the time S1 to the time S2, but the maintenance of such a neutral state is not an essential operation. The operation of the pedal at the end of sewing can also be continuously transitioned from the stepping state to the stepping back state. In this case, when the neutral position is passed during the transition, there is no signal state in which neither the stepping signal 21a nor the stepping signal 21b is given, and the control unit 8 triggers such a no-signal state as described above. The fray prevention operation is started after the needle 2, 2 is raised to the vicinity of the top dead center and the looper 1 enters the left end.

In the timing chart of FIG. 5, the stepping operation of the pedal executed at time S2 is continued in the execution of the fray preventing operation shown below, but such a continuous stepping operation is not essential, and the control portion 8 is not necessary. The fray preventing action can be continuously performed even after the input of the stepping signal 21b is stopped.

Fig. 6 shows the states of the needles 2, 2 and the looper 1 at the start of the fray prevention action. The needles 2, 2 are in a state of being pulled out above the sewing material of the stitch M in which the double stitches are formed by the two needle threads 6, 6 and the looper thread 7. The looper 1 is leftward on the lower side of the above-mentioned sewing material, and is in a state in which two needle thread loops respectively formed by the needle threads 6 and 6 are caught. In this state, when the needle thread 6, 6 and the looper thread 7 are cut, the sewing end portion as shown in Fig. 22A is formed.

After the start of the fray prevention operation, the control unit 8 first gives an operation command to the wire-wound solenoid 32 on the output side, and causes the wire-wound solenoid 32 to be excited for a short time. The hook hook 3 is moved from the standby position shown in FIG. 1 to the hanging position by the excitation of the hook solenoid 32.

This movement is performed while the front end portion 4a of the stopper rod 4 is opened to the left as described above.

After the thread hook 3 is passed, the stopper rod 4 moves to the restriction position shown by the solid line in Fig. 2 due to the elastic force of the return spring (not shown). The hanging hook 3 is oscillated clockwise due to degaussing of the hanging solenoid 32. This swing is restricted by the locking portion 3d of the hook hook 3 reaching the front end portion 4a of the stopper rod 4 at the restriction position, and the hook hook 3 is stopped at the holding position shown in FIG.

In Fig. 7, the front end portion of the hook hook 3 that is moved to the hanging position is shown. The hook portion 3b of the front end of the hook hook 3 as described above passes from the left side of the looper 1 through the lower side of the looper thread 7 to the left and right needle drop positions A and A, and the rear side of the looper 1 is beyond the left side ( The position of the needle thread loop of the entry end side of the looper 1. In Fig. 8, the front end portion of the hook hook 3 that has moved to the holding position is shown. The hook portion 3b of the front end of the hook hook 3 is moved from the hanging position to the right rear, and the sewing thread loop on the left side is caught and held during the movement.

After the hook hook 3 is actuated as described above, the control unit 8 gives an operation command to the sewing machine motor 26 and the feed reduction mechanism 29 on the output side at time S3 in Fig. 5 . This operation command is referred to the needle position signal 22, and is raised after the needles 2 and 2 are lowered, and is applied until the vicinity of the top dead center. Thereby, the sewing material is sewn by one stitch, and this sewing is performed by the action of the feed reducing mechanism 29 at a smaller feeding amount than in the case of normal sewing.

During this period, the control unit 8 gives a short-time operation command to the limit solenoid 42 to excite the limit element solenoid 42 for a short time. By the excitation, the stopper rod 4 is moved from the restriction position shown by the solid line in FIG. 3 to the retracted position indicated by the two-dot chain line, and the restriction of the hook hook 3 is released. Thereby, the hook hook 3 is returned from the holding position to the standby position.

8 to 12 show the states realized during the operation in order. The feed movement of the sewing material ends before the descending needles 2, 2 pass. The hook hook 3 maintains the holding position until the feeding of the sewing material is completed, as shown in Fig. 8, in a state in which the needle thread loop on the left side is held. The needles 2, 2 are lowered through the sewing material in this state. At this time, as shown in FIG. 8, the needle 2 on the right side captures the looper thread 7 on the rear side of the looper 1, and the needle 2 on the left side captures the looper thread 7 on the rear side of the looper 1, and is held from the hook hook 3 The needle thread loop passes through and captures the needle thread loop.

When the needle 2 on the left side catches the needle thread loop, the hook hook 3 moves to the standby position by releasing the restriction of the limit lever 4, and as shown in FIG. 9, the needle loop is released. The looper 1 performs a right retreat operation together with the lowering of the needles 2, 2, and exits from the needle thread loop as shown in FIG. At this time, the needle 2 on the right side captures only the looper thread 7, and the needle 2 on the left side captures the state of the looper 7 and the loop of the needle thread 6.

In this state, the looper 1 is converted to the leftward, and the needles 2, 2 are converted to the rise. As shown in Fig. 11, the left-handed looper 1 captures the loops of the needles 6, 6 held by the needles 2, 2, respectively, and the raised needles 2, 2 are pulled out from above the sewing material. Thereby, the needle thread 6 on the right side captured by the looper 1 is in a state in which only the looper thread 7 is interlooped, and the needle thread 6 on the left side is in a state in which the looper thread 7 is interconnected and the loop of the previously formed needle thread 6 is self-connected. The state of (intralooping).

As shown in Fig. 12, the sewing operation of one stitch is completed with the needles 2, 2 rising to the vicinity of the top dead center and the looping needle 1 reaching the left end. Thereafter, the control unit 8 stands by until the trimming signal 23 is given, and when the trimming signal 23 is given at time S4 in Fig. 5, the operation command is given to the trimming actuator 58 on the output side, and the trimming actuator is activated. 58 performs the prescribed action. Thereby, the thread trimming hook 50 performs a rightward retreating operation after the leftward movement.

The left-hand trimming hook 50 reaches the entry end shown in Fig. 13 along the upper portion of the looper 1. At this time, the first hook portion 52 at the tip end of the thread trimming hook 50 faces the looper thread 7 extending from the front end of the looper 1 from the right side, and the second hook portion 53 provided at the middle portion of the thread trimmer hook 50 is held from the looper 1 The thread loops of the needle threads 6 and 6 pass through, and are in a state of being opposed to the loop of the needle thread 6 on the right side and the right side.

The thread trimming hook 50 performs a right retreating action after reaching the entry end. At this time, the first hook portion 52 captures the looper thread 7, and the second hook portion 53 catches the two needle threads 6 and 6. The looper thread 7 and the needle thread 6, 6 thus caught are pulled to the exit end of the thread cutter hook 50. At this time, the needle threads 6 and 6 caught by the second hook portion 53 are sheared by being slidably contacted with the blade portion of the tip end of the thread cutter 51, and the looper thread 7 captured by the first hook portion 52 is also passed through with the thread cutter. The blade portion of the front end of the 51 is slidably cut and cut, and is held at a position closer to the looper 1 than the shear position. The thread trimming mechanism 5 having the thread trimming hook 50 and the thread cutter 51 cuts the needle thread 6, 6 and the looper thread 7 by the above operation.

As shown in Figs. 13 and 14, the thread hook 90 is pressed against the sliding portion of the thread cutter 51 by the elastic force of the leaf spring 59 which is in elastic contact with the front side of the lower surface, and the needle thread 6 is performed by the thread cutter 51. The shearing of the hooks 6, 6 and the looper thread 7 becomes accurate under the pressing of the leaf spring 59 described above. The looper thread 7 captured by the first hook portion 52 provided at the front end of the thread trimming hook 50 is held as shown in Fig. 14 after being cut between the lower surface of the thread trimming hook 50 and the leaf spring 59. . The needle threads 6 and 6 captured by the second hook portion 53 are separated into the ends of the stitches M of the two-line lock stitches and the needles 2 and 2 sides after the cutting.

After the cutting operation is completed as described above, the control unit 8 stands by until the needle thread removal signal 24 is given, and when the needle thread removal signal 24 is given at time S5 of Fig. 5, an operation command is issued to the air brush 28 on the output side to make the air Brush 28 moves. The air brush 28 blows air to jump the shear ends of the needles 6, 6 which are continuous on the needles 2, 2 side. Then, at the time S6 of FIG. 5, the control unit 8 issues an operation command to the pressing cylinder 27 on the output side, and the pressing cylinder 27 is operated to raise the pressing foot for pressing, and the series of operations for preventing the fray is ended. .

Thereby, the operator can remove the sewing material that has finished sewing from the needle board P, and install a new sewing material to start the next sewing. At this time, the looper thread 7 is held under the needle plate P by the thread cutter hook 50 and the thread cutter 51, and the needle thread 6, 6 jumps onto the needle board P, as shown in Fig. 14, which are suspended from the needles 2, 2, respectively. status. Therefore, the operator does not need to perform any processing on the needle thread 6, 6 and the looper thread 7 to start the next sewing.

The shearing of the needle threads 6 and 6 and the hook thread 7 by the thread trimming mechanism 5, the jump of the needle threads 6 and 6 by the operation of the air brush 28, and the rise of the foot based on the operation of the pressing cylinder 27 are not the present invention. The necessary action in . Further, in the embodiment, these operations are performed while waiting for the trimming signal 23 and the needle thread removing signal 24 given from the outside, but it may be implemented as a series of operations after the sewing of one stitch for fray prevention is completed.

FIG. 15 is a plan view schematically showing a configuration of a main part of the thread fray preventing device of the second embodiment, and FIG. 16 is a view schematically showing a configuration of a main part of the wire fray preventing device of the second embodiment. FIG. 17 and FIG. 18 are explanatory views of the operation of the thread fray preventing device of the second embodiment. In the following description, "left, right" and "front and back" indicated by arrows are used in Figs. 15 and 16 .

The stitch fray preventing device of Embodiment 2 includes a hook hook 3 and a limit lever 4, and further includes a swing lever 9. As shown in Fig. 15, the hook hook 3 is supported by the upper surface of the needle board table 10 on which the needle plate P is attached so as to be swingable about the support shaft 34 in the up-and-down direction. The fulcrum 34 is located in the vicinity of the needle plate P on the right rear side of the needle plate P.

The hanging hook 3 has a circular arc-shaped curved shape, and is connected to the front end portion of the support arm 3e extending leftward from the support shaft 34 to the front. On the lower side of the needle plate P, the front end portion of the hook hook 3 is adjacent to the needle drop positions A, A from the left rear side, and a hook portion 3b that protrudes outward is provided at the front end portion. The support arm 3e also extends forward from the support shaft 34, and one end portion of the connecting rod 35 is coupled to the extended end.

The swing lever 9 is supported by the upper surface of the needle plate stage 10 so as to be swingable about the support shaft 90 in the up-and-down direction. The support shaft 90 is located away from the support shaft 34 of the hook hook 3 to the right. The swing lever 9 extends forward from the support shaft 90, and the other end portion of the connecting rod 35 is connected to the front end portion of the swing lever 9.

The swing lever 9 includes a pressure plate 91 integrally formed by bending a right side near the front end portion downward. As shown in FIG. 16, on the lower surface of the needle plate stage 10, a thread-hanging cylinder 92 is fixed to the left side of the swing lever 9. The hanging line cylinder 92 is an air cylinder having an output rod 93 that protrudes to the right. The front end of the output rod 93 is opposed to the pressure plate 91. The output rod 93 enters and exits due to the action of the working air supplied to the hanging cylinder 92 through the air tube 94, and presses the pressure plate 91 to the right.

The needle plate stage 10 has a spring fixing rod 95 projecting forwardly on the left side of the hanging cylinder 92, and a return spring 96 is disposed between the spring fixing rod 95 and the pressure plate 91. The return spring 96 is a coil spring that biases the pressure plate 91 to the left and is disposed between the connecting rod 35 and the hanging cylinder 92. In FIGS. 15 , 17 , and 18 , a part of the return spring 96 is shown in the middle of the connecting rod 35 .

In the case where the hanging cylinder 92 is in the non-operating state, the swing lever 9 is pulled to the left by the elastic force of the return spring 96, and is in the swing position shown in FIG. The hook hook 3 is coupled to the swing lever 9 via the connecting rod 35. As shown in Fig. 15, the hook portion 3b at the distal end is in a standby position away from the left rear of the needle drop positions A, A (bend needle 1).

When the hanging cylinder 92 is operated, the output rod 93 enters and presses the pressing plate 91 to the right. By this pressing, the swing lever 9 swings counterclockwise against the elastic force of the return spring 96 as indicated by an arrow in FIG. The support arm 3e of the hook hook 3 swings counterclockwise about the support shaft 34, and the hook hook 3 enters to the right front as shown by the arrow in Fig. 17, and the hook portion 3b at the front end of the hook hook 3 is as shown in Fig.17. The position of the hook line reaching the vicinity of the needle drop positions A and A is the position of the needle thread loop which is located on the rear side of the looper 1 beyond the left side (the entry end side of the looper 1) as in the first embodiment.

As shown in FIG. 16, the stopper rod 4 is supported by the lower surface of the needle plate stage 10 so as to be swingable about the support shaft 44 in the up-down direction. The support shaft 44 is located in the vicinity of the support shaft 90 of the swing lever 9. The limit lever 4 extends from the support shaft 44 to the right. The stopper rod 4 has a pressure plate 45 integrally formed by bending a rear side near the front end portion downward, and has an engagement concave portion 46 that forms a notch in the middle portion of the front edge.

On the lower surface of the needle board table 10, a limit cylinder 47 is fixed in the vicinity of the rear end portion. The limit cylinder 47 is an air cylinder having an output rod 48 that projects rearward. The front end of the output rod 48 is opposed to the pressure plate 45. The output rod 48 enters by the action of the working gas supplied to the limit cylinder 47 via the air tube 49, and presses the pressure plate 45 rearward.

On the upper surface of the needle plate stage 10, a spring fixing rod 97 protrudes rightward from the upper side of the limiting cylinder 47, and a return spring 98 is interposed between the spring fixing rod 97 and the front end portion of the limiting rod 4. The return spring 98 is a coil spring that biases the front end portion of the stopper rod 4 rearward. In Figs. 15, 17, and 18, a part of the needle plate 10 is cut away to show a connecting portion between the return spring 98 and the stopper rod 4.

When the limit cylinder 47 is in the non-operating state, the limit lever 4 is pulled forward by the elastic force of the return spring 98, as shown in Fig. 16, at a position where the leading edge abuts against the pressure plate 91 of the swing lever 9. In this state, in the case where the hanging cylinder 92 is operated, the pressure plate 91 is moved to the right along the leading edge of the stopper rod 4. The stopper rod 4 is pulled by the elastic force of the return spring 98 at the timing when the moving pressure plate 91 matches the engagement recess 46 provided at the leading edge, and swings counterclockwise in FIG. 16, as shown in FIG. The bottom surface of the recess 46 abuts against the state of the pressure plate 91 of the swing lever 9.

In this state, in the case where the hanging cylinder 92 is in the non-operating state, the swing lever 9 is pulled to the left by the elastic force of the return spring 96, and is swung clockwise as indicated by an arrow in FIG. The pressure plate 91 slides in the engagement recess 46 of the stopper rod 4, and the swing is restricted at a position where the pressure plate 91 is engaged with the left edge of the engagement recess 46. At this time, the support arm 3e of the hook hook 3 swings clockwise around the support shaft 34, and the hook hook 3 moves backward toward the left rear as indicated by an arrow in FIG. As shown in Fig. 18, the hook portion 3b at the front end of the hook hook 3 is moved to the holding position in the vicinity of the above-mentioned hanging line position, and the needle thread loop on the left side is caught and held in the same manner as in the first embodiment.

In this state, in the case where the limit cylinder 47 is operated, the output rod 48 enters, and the pressure plate 45 of the limit lever 4 is pressed backward. By this pressing, the stopper rod 4 swings against the elastic force of the return spring 98. The engagement recess 46 provided in the limit lever 4 is moved to the rear, and the engagement with the pressure plate 91 is released. Thereby, the swing lever 9 swings clockwise by the elastic force of the return spring 96, and the hook hook 3 moves from the holding position to the left rearward, and returns to the standby position shown in FIG. The stopper rod 4 swings under the elastic force of the return spring 98 due to the inoperative state of the limit cylinder 47, and returns to the swing position shown in FIG.

In the thread fray preventing device of the second embodiment, the hook hook 3 is selectively moved between the hanging cylinder 92 and the limiting cylinder 47 to move between the standby position, the hanging position, and the holding position, thereby enabling The same fray prevention method of the first embodiment. The hanging cylinder 92 corresponds to a hook actuator, and the limiting cylinder 47 corresponds to a limit actuator.

The above-described action of the stitch fray preventing device of the second embodiment is such that the hanging cylinder 92 and the limiting cylinder 47 are controlled objects, and more specifically, the working air is supplied to the hanging cylinder 92 and the limiting cylinder 47. The discharge valve is a control object, and can be realized by the control unit 8 configured as shown in FIG. 4 performing the same control operation as the timing chart shown in FIG. 5.

Fig. 19 is a view showing a stitch of the sewing terminal portion obtained by the present invention as seen from the back side of the sewing material, and Figs. 20 and 21 are explanatory views of the effect of preventing the strand fray shown in Fig. 19. Since these figures are the figure seen from the back side of the sewing material, they are opposite to the left-right relationship of FIGS. 6-14, However, in the following description, the left and the right in FIGS. 6-14 are used. In Figs. 19 to 21, the feed moving direction of the sewing material is a direction indicated by a white arrow, and in Figs. 19 to 21, the upper side is the rear and the lower side is the front.

As shown in Fig. 19, the looper thread 7 is formed from the needle thread loop 6a on the right side (the left side in Fig. 19) of the back surface of the sewing material at the end of the stitch M of the double stitch stitching (hereinafter, it becomes the right final loop 6a). The inner passage is folded back from the front side of the needle thread 6 which is pulled out from the back surface of the sewing material at the time of sewing for one stitch of the fray prevention, and is cut at the position passing through the right final looper 6a again.

On the other hand, the needle thread 6 on the left side (the right side in Fig. 19) which is pulled out from the back surface of the sewing material at the time of sewing at the time of sewing is as described above, and is formed on the left side of the back side of the sewing material at the time of usual sewing. The needle thread loop 6b (hereinafter referred to as the left final loop 6b) (in the right side in Fig. 19) passes through, and the left final loop 6b is self-joined to form a stitch of a single loop slit. Therefore, the looper thread 7 is in a state of being pressed between the needle thread 6 on the left side and the left final thread loop 6b as shown.

In FIGS. 19 to 21, the left final wire loop 6b is shown in a slack state for the purpose of clearly winding the needle thread 6, and the actual left final loop 6b is tightened after the needle thread 6 passes, becoming the right final loop. 6a the same state. Therefore, the looper thread 7 is firmly pressed by the needle thread 6 and the left final thread loop 6b, as shown, being restricted in a state of being pulled between the left final loop 6b and the left stitch loop 6c formed by the previous one. This restriction can be maintained for any direction applied to the looper thread 7, and therefore, the occurrence of the fray characteristic of the stitch M of the double-line lock stitch can be reliably prevented from occurring.

As described above, the feed distance of the sewing material at the time of sewing of one stitch is smaller than the feed pitch at the time of usual sewing. Therefore, as shown in Fig. 19, the interval L between the pull-out position of the needle thread 6 and the left final loop 6b at the time of sewing of one stitch is higher than that of the left stitch loop 6b formed by the left final loop 6b and the previous one. The interval L0 is small. Thereby, the pressing of the looper thread 7 between the needle thread 6 on the left side and the left final loop 6b is reinforced, and the occurrence of the fray caused by the escape of the looper thread 7 can be more reliably prevented.

From the viewpoint of strengthening the pressing of the looper thread 7, the above-described interval L is preferably as small as possible. On the other hand, in the case where the interval L is small, for example, in the thin sewing material, the strength between the extraction position of the needle thread 6 and the left final thread loop 6b is insufficient, which may cause damage to the sewing material. Therefore, the above-described interval L, that is, the feed distance of the sewing material at the time of sewing of one stitch is required to be appropriately set depending on the type of the sewing material.

Fig. 20 shows a state in which the sheared end portion of the looper thread 7 is pulled in the direction indicated by the arrow in the figure. In the case of such pulling, as described above, the loop of the looper thread 7 passing before the needle thread 6 on the same side is narrowed and pulled into the right final loop 6a. As a result, the needle thread 6 is sandwiched between the looper thread 7 and the right final loop 6a to be in the state shown in Fig. 20, and the needle thread 6 and the looper thread 7 are used to form a "knot" as shown. This "knot" exerts a resistance to the looper thread 7 and acts to prevent the looper thread 7 from coming out. When the state shown in Fig. 20 is reached, the line of the double-line lock stitch is passed through the left self-joining portion and The multiplication of the "knot" on the right side can be prevented more reliably.

The pulling of the looper thread 7 as described above naturally occurs when the looper thread 7 is cut or when the stitching material is removed from the needle board P, and the state of the sewing end portion shown in Fig. 20 is prevented in the fray line of the present invention. No additional operations can be implemented during the implementation of the method.

On the other hand, when the sheared end portion of the looper thread 7 is pulled in a direction opposite to the arrow in FIG. 20, it is released from the right final loop 6a, and the state shown in FIG. 21 is obtained. In this case, the self-connection formed by the left final wire loop 6b and the needle thread 6 is maintained, and the escape of the looper thread 7 is prevented at the self-joining portion. Therefore, the fray to the start end of the sewing thread is stopped at the position of the self-joining portion on the left side, and the occurrence of the fray characteristic peculiar to the stitch M of the double-line stitching can be prevented.

In the above embodiment, the stitches of the two-line lock stitch formed by the two needle threads 6, 6 and the looper thread 7 are explained, and the fray line preventing device of the stitch of the present invention and the stitching performed by the device are disclosed. The wire prevention method is also applicable to the stitch of the double-line lock stitch using three or more needle threads, and the occurrence of the fray can be effectively prevented.

In the above embodiment, the case where one of the needle thread loops formed by the two needle threads 6 and 6 is located on the entry end side of the looper 1 and the sewing operation of one stitch is performed in this state is described, but the capture is performed. The sewing thread loop may be a plurality of loops including one of the entry end sides of the looper 1, and the sewing operation performed in such a holding state may be two or more stitches.

As apparent from the above description, in the present invention, the looper is in the entering state at the end of the sewing, and the loop of the needle thread caught by the looper is held on the rear side, and in this state, the sewing operation of at least one stitch is performed. Since the needle thread loop held by the needle thread is self-joined by the needle which is lowered by the needle, the looper thread is reliably pressed at the self-joining portion of the needle thread, and the yarn strand can be effectively prevented from occurring at the stage of occurrence. The pressing of the looper line formed by the self-joining portion is hardly affected by the tension of the needle thread, and the occurrence of the fray can be prevented more reliably.

The above-described embodiments are intended to at least clarify the technical content of the present invention, and the present invention should not be construed as being limited to the embodiments, and can be carried out without departing from the scope of the invention and the scope of the claims. Implemented with various changes.

1. . . Curved needle

3. . . Hanging hook

3a. . . arm

3b. . . Hook

3c. . . Step

3d. . . Clamping part

4. . . Limit rod

4a. . . Front end

4b. . . Step

5. . . Wire cutting mechanism

8. . . Control department

twenty one. . . Foot switch

21a. . . Step into the signal

21b. . . Step back signal

twenty two. . . Needle position signal

twenty three. . . Trimming signal

twenty four. . . Needle removal signal

26. . . Sewing machine motor

27. . . Pressing cylinder

28. . . Air brush

29. . . Feed reduction mechanism

30. . . Support shaft

31. . . Link rod

32. . . Hanging wire solenoid

33. . . Swing arm

40. . . Support shaft

41. . . Link rod

42. . . Limit solenoid

43. . . Swing arm

50. . . Thread hook

51. . . Wire cutter

52. . . First hook

53. . . Second hook

54. . . Pedestal

54a. . . Support shaft

55. . . Swing rod

56. . . Slider

57. . . Wire cutter

57a. . . Support shaft

58. . . Trimming actuator

Fig. 1 is a plan view schematically showing a configuration of a main part of a thread fray preventing device of a first embodiment.

Fig. 2 is a plan view schematically showing a configuration of main parts of a thread fray preventing device of the first embodiment.

FIG. 3 is a plan view schematically showing a configuration of a main part of the strand fray preventing device of the first embodiment.

Fig. 4 is a block diagram showing a control system of the sewing machine having the stitch fray preventing device of the first embodiment.

FIG. 5 is a flowchart showing the operation of the control unit.

Fig. 6 is an operation explanatory view of the stitch line preventing device.

Fig. 7 is an explanatory view of the dynamic lock of the thread fray preventing device.

Fig. 8 is an operation explanatory diagram of the stitch fray preventing device.

Fig. 9 is an operation explanatory diagram of the stitch fray preventing device.

Fig. 10 is an operation explanatory diagram of the stitch fray preventing device.

Fig. 11 is an operation explanatory diagram of the stitch line preventing device.

Fig. 12 is an operation explanatory diagram of the stitch fray preventing device.

Fig. 13 is an operation explanatory view of the stitch line preventing device.

Fig. 14 is an operation explanatory diagram of the stitch line preventing device.

FIG. 15 is a plan view schematically showing a configuration of a main part of a thread fray preventing device according to a second embodiment.

FIG. 16 is a bottom view schematically showing a configuration of a main part of a thread fray preventing device according to a second embodiment.

Fig. 17 is an operation explanatory view of the stitch line preventing device of the second embodiment.

Fig. 18 is an operation explanatory view of the stitch line preventing device of the second embodiment.

Fig. 19 is a view of a stitch of a sewing end portion obtained by the present invention as seen from the back side of the sewing material.

Fig. 20 is an explanatory view showing the effect of preventing the line fray prevention by the present invention.

Fig. 21 is an explanatory view showing a stray fray prevention effect obtained by the present invention.

22A and 22B are views showing a general stitch of the sewing end portion and a stitch of the sewing end portion obtained by the conventional fray preventing device from the back side of the sewing material.

1. . . Curved needle

3. . . Hanging hook

3a. . . arm

3b. . . Hook

3c. . . Step

3d. . . Clamping part

4a. . . Front end

4b. . . Step

5. . . Wire cutting mechanism

30. . . Support shaft

31. . . Link rod

32. . . Hanging wire solenoid

33. . . Swing arm

40. . . Support shaft

41. . . Link rod

42. . . Limit solenoid

43. . . Swing arm

50. . . Thread hook

51. . . Wire cutter

52. . . First hook

53. . . Second hook

54. . . Pedestal

55. . . Swing rod

56. . . Slider

57. . . Wire cutter

P. . . Needle plate

Claims (6)

A method for preventing a fray of a stitch for preventing a fray of a stitch of a double-line lock stitch, wherein the double-line lock stitch is passed through a needle thread loop formed by holding a plurality of needles moving downward on the needle thread under the needle plate The curved needle entering in the direction in which the needles are arranged is caught by the looper thread held by the looper, and the needle thread is interconnected to form a sewing material for feeding movement on the needle plate. The above method is characterized in that At the end of the sewing, the looper is placed in an entry state, and at least one of the plurality of needle loops captured by the looper including the needle loop on the entry side of the looper is on the rear side of the looper While maintaining the above-described state, the sewing operation is performed for at least one stitch, and the needle that has descended to the held needle thread loop passes, and the needle thread loop is self-joined by the needle thread held by the needle. The fray line preventing method according to the first aspect of the invention, wherein the sewing operation is stopped by stopping the feeding of the sewing material or by making the feeding distance of the sewing material smaller than that during normal sewing. A fray preventing device for a stitch is provided in a sewing machine for preventing a fray of a stitch of a double-line stitching, the sewing machine comprising a plurality of needles for holding the needle thread to move downward, and a holding looper thread for arranging the needles a looper that advances and retreats, captures a needle thread loop formed by the plurality of needles under the needle plate through the entry of the looper, and interconnects the needle thread by a looper thread held by the looper, and stitches the double stitch The stitch is formed on the sewing material for feeding movement on the needle plate, and is characterized by comprising: a needle thread holding mechanism that performs an approaching and leaving motion with respect to the curved needle on the rear side of the curved needle, and captures the above when approaching the movement And at least one of the plurality of needle thread loops captured by the looper includes at least one stitch thread loop on the entry side of the looper; and the control portion, the movement of the needle and the looper, and the seam The feeding operation of the material controls the approaching and leaving operation of the needle thread holding mechanism in association with the control unit, and the control unit ends the passage when the looper is in the entering position and the needle is in the rising position. After the sewing, the needle thread holding mechanism is moved to hold the needle thread loop, and the above-described state is maintained, and at least one lowering and raising of the needle is performed in accordance with the advancement and retreat operation of the looper and the feeding operation of the sewing material. One stitching sewing action. The fray line preventing device according to the third aspect of the invention, wherein the control unit performs the feed amount of the feed operation of the sewing material to be zero or the amount of the needle is smaller than a normal sewing time. Sewing action. The floss preventing device for a stitch according to claim 3, wherein the needle thread holding mechanism includes: a hook hook and a limit rod, and is disposed under the needle plate, substantially in comparison with the needle plate Parallel in-plane oscillation; a hook actuator that swings the hook hook from a standby position away from the looper to a hook line position adjacent to the looper; and a limit actuator that causes the limit lever to exit from the hook The retracted position of the swinging region of the wire hook is swung to a restricted position in contact with a portion of the hook hook, and the control portion selectively controls the hook actuator and the limit actuator to be in contact with the limit lever The needle thread loop caught by the hook hook at the hook position is held at a holding position between the hook position and the standby position, and the sewing operation of the one stitch is performed in the above state. The floss preventing device for a stitch according to claim 3, wherein the needle thread holding mechanism includes: a hook hook disposed under the needle plate in a plane substantially parallel to the needle plate Swinging; the swinging rod and the limiting rod are disposed at a position farther from the needle plate than the hook line, swinging in a plane substantially parallel to the needle plate; connecting the hook of the hook and the connecting rod of the swinging rod; The swing lever swings the hook hook from a standby position away from the looper to a hook actuator near a hook position of the looper; and engages the limit lever from a portion of the swing lever a position limit actuator that swings to a retracted position away from the engagement position, the control unit selectively controls the hook actuator and the limit actuator, and the engagement of the limit lever with the swing lever is The needle thread loop caught by the hook hook at the hook position is held at a holding position between the hook position and the standby position, and the sewing operation of the one stitch is performed in the above state.