JP2008253448A - Skip stitch device for double chainstitch machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a skip stitch device for a double chainstitch machine, which allows an operator to skip stitches as intended and non-restricting the design of a sewing machine. <P>SOLUTION: This skip stitch device 40 for the double chainstitch machine 10 includes a plurality of loopers 15 each catching a loop of a sewing thread T from a sewing needle 12 vertically moving by a swinging operation at its hook point and making the looper thread L insert therein, and a plurality of claws 31 of a spreader 30 each catching the looper thread L from the hook point of each looper 15 and forming a loop; and execute the sewing with at least two or more sewing needles; wherein at least tip end of each claw 31 retreats to a position for non-catching the looper thread L by turning operation by the skip stitch device 40. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a stitcher for a chain stitch sewing machine.

As shown in FIG. 7, the chain stitch sewing machine has a needle bar (not shown) that moves up and down while holding the sewing needle 101 and a loop of the sewing thread T by swinging the sword tip 102 along the cloth feed direction. A looper 103 for inserting the looper thread L and a spreader 104 for forming a loop for capturing the looper thread L and inserting the sewing needle 101 are provided.
With this configuration, the advancing looper 103 captures the sewing thread T from the sewing needle 101 that has descended through the fabric at the sword tip 102, and the spreader 104 captures the loop thread L from the looper 103 inserted through the loop of the sewing thread T. A loop is formed, and the sewing needle 101 lowered again enters the loop of the looper thread L. By repeating these, the sewing thread T and the looper thread L are intertwined on the lower side of the fabric so that a seam is formed. It has become.

By the way, the chain stitch sewing machine may be used for sewing the waist belt W of the jeans J shown in FIG. This waist belt W is a belt-like fabric sewn around the upper end portion of the jeans J. As shown in FIG. 8 (B), the waist belt W is formed by using at least two sewing needles. The hands are moved in parallel with each other.
When the sewing of one waist belt W is completed, the sewing of the waist belt W is continuously performed by forming an empty ring as it is and shifting to the sewing of the next waist belt W. Therefore, a trial sewing section A corresponding to a predetermined number of stitches is provided at the sewing start end portion of the waist belt W in order to stabilize the seam at the time of transition from the formation of the empty ring to the sewing of the fabric. The trial sewing section A is excised and discarded after sewing.
Furthermore, since both ends of the waist belt W are sewn in a state of being folded inwardly, the waist belt W is subjected to a folding section B on the sewing start end side adjacent to the section A and a normal chain stitch. A folding section D formed on the sewing end end side through the section C is set. In addition, the section E shown in the figure indicates an empty ring section that is continuously performed from the end of the cloth.
Here, with respect to the sewing section D, if the end of the fabric is folded inward in advance and sewing is performed from above, the folded state is completed, but the folding section B is adjacent to the test sewing section A. Therefore, the end cannot be folded before the section A is excised. For this reason, after cutting out the section A, the section B is folded inward and then sewn in a separate step. At this time, in the case of the section B, as in the case of the section C, it is necessary to once unwind the seam in order to fold the end portion inward when normal chain stitching is performed. However, since this work is very complicated, a method called “skip” is generally used for the section B.
This “fly skipping” is the artificial thread insertion of one of the sewing thread and looper thread to the chain stitch that forms the seam by alternately inserting the loop of the sewing thread and the loop of the looper thread for each stitch. It means that the seam is not formed by blocking.

As a skipping device that performs skipping in the prior art, a spreader including a claw that performs reciprocating motion in a direction (left-right direction) orthogonal to the reciprocating motion direction of the looper to hook the looper yarn is set in one direction of reciprocating motion. There is one in which the spreader is retracted to a position where the spreader does not catch the looper thread by fixing after being moved (Patent Document 1).
JP-A 61-279282

However, in the conventional stitching device for a chain stitch sewing machine, as shown in FIG. 9A, in a chain stitch sewing machine having a plurality of needles and a looper, the direction in which the plurality of loopers are arranged, the direction in which the nails are arranged, and the reciprocating movement of the nails If the spreader moved in one direction of the reciprocating movement does not secure enough space to retract the spreader moved in one direction of the reciprocating movement because the direction matches the direction of the spreader There is a problem that a part of the looper thread is hooked and a chain stitch unintended by the operator is performed. Further, even if the above-mentioned problem is when the retracting direction of the spreader is the other of the left and right reciprocating movements, as shown in FIG. 9 (b), the spreader is stopped in order to finish the skipping and resume the chain stitching. This could occur when moving to a position where it can be skipped.
In order to avoid this problem in the prior art, a very large space is required in the direction in which the loopers are arranged in order to prevent a spreader whose left-right motion position has been changed from catching a nearby looper thread. As a result, there is a problem that it is difficult to arrange more loopers side by side.

  SUMMARY OF THE INVENTION In view of the above-described problems, the present application has an object of providing a chain stitch sewing machine skipping device that can skip a stitch as intended by an operator and does not limit the design of the sewing machine.

  According to the first aspect of the present invention, there are provided a plurality of loopers for inserting a looper thread by supplementing a loop of a sewing thread from a sewing needle that moves up and down with a sword by a swinging operation, and the looper thread from the sword tip of each looper. And a plurality of protrusions for forming a loop, and a stitch skipping device for a chain stitch sewing machine that performs sewing with at least two sewing needles, wherein at least a tip portion of each protrusion is provided on each looper. A retracting means for retracting in the forward direction is provided, wherein the retracting means rotates each of the protrusions.

According to the first aspect of the present invention, since the tip portion of each projection is retracted in the forward direction of the looper, the adjacent looper yarn is not caught by the retraction of each projection, and the operator can reliably perform any timing. Can be skipped.
In addition, in a chain stitch sewing machine equipped with a plurality of needles and loopers, it is possible to skip the stitches correctly regardless of the spacing between the loopers, so there is no need to consider retracting the skipping device for the spacing between the loopers. The degree of freedom is greatly improved.
Further, since the skipping can be executed only by rotating the tip portions of the plurality of claws, a space for retracting the spreader is not required as in the prior art, and a space for retracting the spreader is secured. In addition, the sewing machine does not increase in size, and space can be saved.
Furthermore, even if the number of loopers is increased, there is no effect on securing the evacuation space, so it is possible to mount more loopers.

(Overall configuration of the embodiment of the invention)
A chain stitch sewing machine 10 according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a perspective view of a chain stitch sewing machine 10.
Hereinafter, the direction parallel to the upper surface of the needle plate 11 described later and parallel to the cloth feeding direction is the X-axis direction, the direction parallel to the upper surface of the needle plate 11 and perpendicular to the X-axis direction is the Y-axis direction, and the needle plate 11, each part of the sewing machine will be described with the direction perpendicular to the upper surface of the machine 11 as the Z-axis direction.

  The chain stitch sewing machine 10 includes a needle bar 14 having a needle holding portion 13 that can hold a plurality of sewing needles 12, a vertical movement mechanism (not shown) that moves the needle bar 14 up and down, and a cloth feed direction (X-axis direction). ) And a plurality of loopers 15 for individually inserting the looper thread L into the loop of the sewing thread T of each sewing needle 12, and a looper for holding the return amount of each looper 15 so as to be individually adjustable. A holding mechanism 20, a swing mechanism (not shown) that swings each looper 15 via the looper holding mechanism 20, and the looper thread L is captured by moving in the direction intersecting the trajectory of the sword tip 15 a with respect to each looper 15. In addition, the spreader 30 provided with the claw 31 as a sharp projection for forming a loop, a reciprocating mechanism (not shown) for reciprocating the spreader 30 along the Y-axis direction, and skipping during sewing are executed. And eye skip device 40, and a main body frame 50 for holding the respective configuration.

(Body frame)
The main body frame 50 is formed in a substantially U shape as a whole, and is located at the bottom of the frame.
A bed portion 51 extending along the axial direction, a standing body portion 52 standing from one end portion of the bed portion 51, and extending from the upper end portion of the standing body portion 52 in the same direction as the bed portion 51. Arm portion 53.
A sewing machine motor (not shown) that is mainly used as a driving source for the vertical movement of the needle bar 14 is built in the upper end of the standing body 52, and the arm 53 is driven to rotate by the sewing machine motor. The shaft is built in a state along the Y-axis direction. The bed portion 51 incorporates a lower shaft (not shown) that is rotationally driven from the upper shaft via a timing belt in a state along the Y-axis direction.

(Needle bar and vertical movement mechanism)
The vertical movement mechanism includes a rotary weight fixedly provided at one end of the upper shaft, and a crank rod that connects between the rotary weight and the needle bar 14, and converts the rotary motion of the rotary weight into a vertical motion so that the needle Transmit to bar 14.
The needle bar 14 is supported at the surface side end of the arm portion 53 so as to be movable up and down.
A needle holder 13 is provided at the lower end of the needle bar 14. The needle holding portion 13 can hold up to four sewing needles 12 side by side in the Y-axis direction and can hold two sewing needles 12 in proximity to each other.

(Looper, looper holding mechanism and swing mechanism)
The looper 15, the looper holding mechanism 20, and the swinging mechanism are built in the bed portion 51 below the needle plate 11.
FIG. 2 is a perspective view showing the looper 15 and the looper holding mechanism 20, and FIG. 3 is a side view seen from the surface side of the sewing machine. As shown in the figure, each looper 15 is formed in a bowl shape with a sharpened sword tip 15a so that the extending direction and the reciprocating direction of each sword tip 15a are along the X-axis direction (cloth feeding direction). It is held by the looper holding mechanism 20. Further, the tip of the sword tip 15a is directed in the direction opposite to the cloth feeding direction. Each looper 15 is formed with a guide groove 15b that guides the looper yarn L to the vicinity of the sword tip 15a along the extending direction on one side surface thereof. An insertion hole 15c for the looper thread L is formed in the penetrating state from the end of the guide groove 15b to the upper surface of the looper in the vicinity of the sword tip 15a. That is, the looper yarn L is guided from the rear of the looper 15 to the vicinity of the sword tip 15a along the guide groove 15b, folded back through the insertion hole 15c, and hung back along the upper surface of the looper 15. Yes.
With this structure, the looper 15 has its sword tip 15a inserted into the loop of the sewing thread T inserted through the lowered sewing needle 12 when moving forward by swinging. A triangular loop is formed.
Reference numeral 16 denotes a needle receiver formed by bending from a round bar, and is a member for adjusting the sewing thread T to a position where the sewing thread T is easily caught by the looper 15 by slidingly contacting the descending sewing needle 12.

  The swing mechanism is a swing that holds an eccentric cam provided on a lower shaft that performs full rotation, a crank rod having one end connected to the eccentric cam, and a swing arm connected to the other end of the crank rod. And a shaft 17. The swing shaft 17 is arranged in parallel with the lower shaft and is adjusted to swing within the swing angle range of the looper 15.

  The looper holding mechanism 20 includes a holding body 21 that is fixedly attached to one end portion of the swing shaft 17 and an arm portion 21 a of the holding body 21 that extends in the radial direction around the swing shaft 17. An adjustment shaft 22 as a support shaft provided, a plurality of holding arms 23 for individually holding the loopers 15 at the tip end portions, and a fastening screw 24 for fastening the holding arms 23 to the adjustment shaft 22 are provided.

The holding body 21 includes an arm portion 21a extending in a direction perpendicular to the swing shaft 17, and the arm portion 21a holds the adjustment shaft 22 in a state along the Y-axis direction at the extending end portion. ing.
The adjusting shaft 22 is held by the arm portion 21a at an intermediate portion in the longitudinal direction, and two holding arms 23 can be provided at both ends thereof. The adjustment shaft 22 is configured such that four loopers 15 are arranged along the Y-axis direction via the holding arms 23, and the orbits of the respective sword tips 15a are held by the needle holding portion 13. Each holding arm 23 is held so as to pass through the vertical movement path in close proximity.

Each holding arm 23 is configured such that its base end portion holds and fixes the adjustment shaft 22 with a fastening bolt 24, and its swing end portion extends in a direction perpendicular to the adjustment shaft 22. The looper 15 is fixedly held.
Since each holding arm 23 holds the adjustment shaft 22 with the fastening bolt 24, the angle can be adjusted around the adjustment shaft 22 by loosening the fastening bolt 24. As shown in FIG. By adjusting the swing angle as appropriate and retightening the fastening bolt 24, the burr amount K can be adjusted for each looper 15.
Each holding arm 23 holds the looper 15 with a set screw 23a, and the looper 15 can be removed by loosening the set screw 23a. That is, only the loopers 15 corresponding to the number and arrangement of the sewing needles 12 attached to the needle holding portion 13 described above can be attached.

Here, the burr amount K means the distance from the tip of the sword tip 15a of the looper 15 at the last retracted position to the vertical movement path of the sewing needle 12, as shown in FIG.
By adjusting the burr amount, the timing at which the sword tip 15a captures the sewing thread T can be adjusted with respect to the sewing needle 12 rising from the bottom dead center position.
For example, when resistance to the sewing thread T is likely to occur when the sewing needle 12 penetrates due to the thickness of the sewing thread, slippage, cloth thickness, hardness, fineness, material, etc., or when the sewing thread T tends to stretch, Since the sewing thread T stretched when the sewing needle 12 is inserted is contracted when the sewing needle 12 is raised, the loop is formed small. On the other hand, when resistance to the sewing thread T hardly occurs when the sewing needle 12 penetrates or when the sewing thread T does not expand, the sewing thread T does not contract when the sewing needle 12 is raised, so that a large loop is formed.

When the loop of the sewing thread T is formed large, as shown in FIG. 4, so-called “falling” of the loop in which the direction of the loop changes around the sewing needle 12 is likely to occur. Accordingly, in such a case, the loop amount K of the looper 15 is adjusted to be small so that the sword tip 15a reaches the vertical movement path of the sewing needle 12 at an early stage, and the loop of the sewing thread T before the fall occurs. Can be dealt with by capturing
In addition, when the loop of the sewing thread T is formed small, the loop amount K of the looper 15 is adjusted to be large so that the sword tip 15a can reach the vertical movement path of the sewing needle 12 slowly, and the loop is sufficiently formed. This can be dealt with by capturing the loop of the sewing thread T after the break.

  In the looper holding mechanism 20, the burr amount K can be adjusted individually for each looper 15. For this reason, for example, when the sewing product is sewn to the upper part and the lower part as in the waist belt W (see FIG. 8B), the lower part has a folding back W1 and is higher than the upper part. When the fabric thickness increases, the looper 15 that sews the lower part can be dealt with by setting and adjusting the burr amount larger than that of the looper 15 that sews the upper part. Quality can be improved.

(Spreader and reciprocating mechanism)
FIG. 5 is a perspective view of the main configuration around the looper during normal sewing as seen from above. In addition, normal sewing shall mean the state which is sewing, without performing the skipping by the skipping apparatus 40 mentioned later.
The spreader 30 includes a rod-shaped portion 32 oriented in the Y-axis direction and four claws 31 provided in a predetermined arrangement in the longitudinal direction of the rod-shaped portion 32. Each claw 31 is supported by a rod-shaped portion 32 by a rotation shaft 31 a facing the Z-axis direction, and a rear end portion 31 b of each claw 31 is connected to a support member 43 of the skipping device 40. The rear end portion 31b of each claw 31 and the support member 43 are rotatably connected by a connecting shaft facing the Z-axis direction.
Note that a mechanism for performing skipping by the skipping device 40 will be described later.

The spreader 30 is held by a skipping device 40, and the skipping device 40 is held by a reciprocating mechanism (not shown).
The spreader 30 is held by the reciprocating mechanism via the skipping device 40 as described above, and is switched between the standby position and the operating position by the reciprocating mechanism. In FIG. 5, the standby position of the spreader 30 is indicated by a two-dot chain line, and the operating position is indicated by a solid line.
Each of the claws 31 of the spreader 30 extends in the cloth feeding direction in a state along the X-axis direction, and at the standby position, the four claws 31 exit from the insertion holes 15c of the four loopers 15, respectively. It is arranged on the rod-shaped portion 32 so as to be on the left side in FIG. Further, at the operating position, the claw 31 moves from the standby position to the right in FIG.

  That is, the spreader 30 is in a standby position until each looper 15 moves forward, and moves to the operating position after each looper 15 moves forward so that the tip of each claw 31 moves rearward from the insertion hole 15c of each looper 15. The folded looper yarn L is hooked and moved to the right side. As a result, each looper thread L forms a triangular loop that passes through the insertion hole 15c and the tip of the claw 31, and the needle drop by the sewing needle 12 is performed in the inner area of the loop, so that the loop of the looper thread L It is possible to insert the loop of the sewing thread T into the thread.

The reciprocating mechanism has a function of converting the rotational driving amount of the lower shaft into a reciprocating moving force along the Y-axis direction and transmitting it to the spreader 30. The reciprocating mechanism is adjusted such that the most advanced position and the most retracted position of the reciprocating operation transmitted from the lower shaft position the spreader 30 described above at the standby position and the operating position.
Further, the reciprocating mechanism synchronizes the reciprocating motion of the spreader 30 with the vertical movement of the sewing needle 12 by obtaining power from the lower shaft.

(Blinding device)
FIG. 6 is a perspective view showing the main configuration around the looper during skipping and the entire skipping device.
The skipping device 40 includes a cylinder part 41 that is an air chamber of an air cylinder mechanism, a plunger part 42 that moves forward and backward along the Y-axis direction by the cylinder part 41, and a support member that is connected to the tip of the plunger part 42. 43. Further, the side portion of the cylinder portion 41 is fixed to the fixing portion 30 a of the spreader 30 and holds the spreader 30.
Further, as described above, each claw 31 of the spreader 30 is supported by the rod-like portion 32 by the rotating shaft 31a facing in the Z-axis direction, and the rear end portion 31b of each claw 31 is the support member 43 of the skipping device 40. It is connected to. The rear end portion 31b of each claw 31 and the support member 43 are rotatably connected by a connecting shaft facing the Z-axis direction.

The cylinder part 41 is connected to an air supply source via an electromagnetic valve, and the electromagnetic valve is controlled by a sewing machine control device (not shown). When performing skipping, as shown in FIG. As the portion 41 operates, the plunger portion 42 expands, the support member 43 is moved along the Y-axis direction, and the claws 31 are rotated. Further, in normal sewing, the cylinder unit 41 is operated by the control device of the sewing machine, and the plunger unit 42 is moved so as to contract, so that each claw 31 is hooked on the looper thread L via the support member 43. And positioned.
That is, when performing skipping, each claw 31 is rotated to move the tip of each claw 31 away from each looper 15 and retract to a position where the looper thread L is not caught. Therefore, the cylinder portion 41, the plunger portion 42, and the support member 43 of the skipping device 40 that retracts the claws 31 so as to retract to the position where the looper yarn L is not hooked function as “retracting means”.
In FIG. 6, each claw 31 rotates clockwise when skipping, but the tip of each claw 31 is moved away from each looper 15 to a position where each claw 31 does not hook the looper thread L. For example, it may be counterclockwise.
The cylinder part 41 and the plunger part 42 of the air cylinder mechanism are for holding the support member 43 so as to be movable along the Y-axis direction, and may be anything as long as they function similarly to the air cylinder mechanism. For example, a device provided with a solenoid or a mechanism that replaces the rotational movement of the motor with movement along the Y-axis direction may be used.

(Description of the operation of the chain stitch machine)
A case will be described as an example where sewing is performed with the four sewing needles 12 using the above-described waist belt W (see FIG. 8) as an article to be sewn using the chain stitch sewing machine 10 having the above-described configuration.
The following sewing operations are performed in accordance with control of a sewing machine control device (not shown).
First, when sewing the section A of the waist belt W, the sewing needles 12, the loopers 15, and the spreader 30 operate in synchronization by driving the sewing machine motor. That is, the looper 15 moves forward with respect to the lowered sewing needle 12, and the looper thread L is inserted through the loop of the sewing thread T. Thereafter, the spreader 30 moves from the standby position to the operating position, whereby the tip of each claw 31 captures each looper yarn L and executes loop formation. Then, the sewing needle 12 that descends again performs needle dropping into the loop of the looper thread L, and the sewing thread T is inserted into the loop of the looper thread L. By repeating this operation, double chain stitching for the waist belt W is executed.
The operation of the sewing machine motor is controlled so that the sewing in the section A is performed with a preset number of stitches. When the set number of stitches is counted, the sewing machine motor is automatically stopped.

Next, when the section B is reached, the cylinder portion 41 is operated, and operation control for positioning each claw 31 at the retracted position is performed (state shown in FIG. 6).
As a result, each looper 15 inserts the looper thread L through the loop of the sewing thread T of the lowered sewing needle 12, but each pawl 31 is retracted to a position where the looper thread L cannot be hooked, and the insertion hole 15c by each looper thread L is retracted. And a triangular loop passing through the tip of the claw 31 is not formed, and the sewing needle 12 falls outside the loop of the loop thread L. As a result, the loop of the looper thread L is inserted into the loop of the sewing thread T, but the loop of the sewing thread T is not inserted into the loop of the looper thread L. No seam is formed on the, and the sewn fabrics can be easily separated from each other.
The operation control of the sewing machine motor is performed so that the sewing in the section B is performed with a preset number of stitches. When the set number of stitches is counted, the sewing machine motor is automatically stopped, the cylinder portion 41 contracts, and each claw 31 is positioned again at a position where the tip of each claw 31 is hooked with the looper thread L. Operation control is performed.

Next, in section C, normal sewing is performed, and the best cloth for jeans is sewn on the waist belt W.
At this time, since the spreader 30 is located at the forward movement position, normal sewing is performed. Then, the sewing machine motor stops at the set number of stitches.

Next, in the section D, the cloth end portion is folded inward, and sewing is resumed by, for example, stepping on a sewing pedal (not shown), and sewing is performed from the folded state. Further, after passing through the end of the waist belt W, the sewing is continued as it is to form an empty ring of the section E.
Thereafter, the empty ring in the section E is cut by an empty ring cutting means (not shown) to separate the waist belt W, and the section A is further cut off. Then, the section B is opened and folded inward, sewing is performed from above, and the sewing is completed.
In addition, sewing is continued similarly about the next waist belt W as it is from the empty ring of the section E.

(Effect of embodiment)
According to the above-described embodiment, the tip portion of each claw 31 is retracted in the forward direction of the looper 15, so that the looper yarn L in the vicinity is not caught and the operator can surely skip the eye at an arbitrary timing. it can.
Further, in a chain stitch sewing machine having a plurality of sewing needles 12 and a looper 15, it is possible to skip the stitches correctly regardless of the spacing between the loopers 15. Therefore, it is necessary to consider retracting the skipping device 40 with respect to the spacing between the loopers 15. The freedom in designing the sewing machine is greatly improved.
Furthermore, since the skipping can be performed only by rotating the tip of each claw 31, no space for retracting the spreader is required as in the prior art, and a space for retracting the spreader is secured. In addition, the sewing machine does not increase in size, and space can be saved.
Furthermore, even if the number of loopers 15 is increased, there is no effect on securing the evacuation space, so that more loopers 15 can be mounted.
Further, since the tip of each claw 31 is retracted by the rotation of each claw 31 collectively by the operation of the cylinder part 41, the cylinder part 41 is operated with power for retracting the tip of each claw 31. In addition to being easy to design, the cost can be reduced.

(Other)
Note that the number of the sewing needle 12, the looper 15, and the claw 31 of the spreader 30, and the spacing and arrangement in the Y-axis direction are not limited to the above embodiment.

  Further, the reciprocating operation of the spreader 30 in the Y-axis direction (reciprocating between the standby position and the operating position) is not limited to the configuration that receives power from the lower shaft, and a dedicated driving device may be provided.

Further, the spreader 30 is reciprocated in the Y-axis direction via the skipping device 40. In such a configuration, the spreader reciprocates in the Y-axis direction even when each claw 31 is retracted. . Therefore, a transmission mechanism that can cut the power from the lower shaft when each of the claws 31 is retracted may be provided.
Alternatively, reciprocation in the lower axis direction of the spreader 30 is performed by a dedicated drive source, and control is performed to stop the Y-axis reciprocation drive source when each claw 31 is retracted, and reciprocation is not performed when each claw 31 is retracted. It is good also as a structure.

  Further, a rotation driving source may be provided for each nail, and an arbitrary nail may be selected and retreated by setting.

The perspective view of the chain stitch sewing machine which is embodiment of invention is shown. It is a perspective view which shows the looper and looper holding mechanism which were disclosed by FIG. FIG. 2 is a side view of the looper and looper holding mechanism disclosed in FIG. 1 as viewed from the surface side of the sewing machine. It is a state explanatory view showing the occurrence of the loop fall of the sewing thread. It is the perspective view which looked at the main composition around the looper at the time of normal sewing from the upper part. It is a perspective view which shows the main structure around the looper during execution of skipping, and the entire skipping device. It is a front view of the main structures around the looper of the conventional chain stitch sewing machine. FIG. 8A is an explanatory view of a waist belt in jeans, and FIG. 8B is an explanatory view of a sewing section of the waist belt. It is a perspective view which shows the main structures around a looper provided with the conventional skipping apparatus.

Explanation of symbols

10 Sewing machine 12 Sewing needle 15 Looper 15a Blade tip 30 Spreader 31 Claw (protrusion)
40 Skipping device 41 Cylinder portion 42 Plunger portion 43 Support member L Looper thread T Sewing thread

Claims (1)

A plurality of loopers that allow a loop of a sewing thread from a sewing needle that moves up and down by a swinging movement to supplement the looper thread with a sword tip, and a plurality of loopers that supplement the looper thread from the sword tip of each looper and form a loop. A projection device for a chain stitch sewing machine that performs sewing with at least two sewing needles,
At least the tip of each projection includes a retracting means for retracting in the forward direction of each looper,
The skipping device for a chain stitch sewing machine, wherein the retracting means retracts by rotating the protrusions.

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