JP2007029153A - Stitch skipping device of chain-stitch sewing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely skip stitches even when there are a plurality of sewing needles even in the case of performing two or more lines of sewing. <P>SOLUTION: The stitch skipping device 40 of a chain-stitch sewing machine 10 for performing sewing with the plurality of sewing needles, which is provided with a plurality of loopers 15 for catching the loop of a sewing thread T from the sewing needle 12 and inserting a looper thread L and a spreader 30 provided with a plurality of sharp projections 31 for catching the looper thread from the hook of each looper and forming a loop, comprises a shielding member 41 provided so as to switch a position to a shielding position for shielding the distal ends of the respective projections of the spreader to the respective loopers and a withdrawn position for not shielding them and an operation means 42 for switching the shielding member to the shielding position and the withdrawn position. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

As shown in FIG. 9A, the chain stitch sewing machine has a needle bar (not shown) that moves up and down while holding the sewing needle 101, and a sewing thread T by swinging the sword tip 102 along the cloth feed direction. A looper 103 for inserting the looper thread L through the loop and a spreader 104 for forming a loop for capturing the looper thread L and inserting the sewing needle 101 (see, for example, Patent Document 1).
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 that has been 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 waist of the upper end of jeans J. As shown in FIG. 10 (B), the waist belt W has an upper portion and a lower portion 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 shown in FIG. 9A, the stitch skipping device 110 blows air from the looper 103 side to the sewing needle 101, and a loop of the sewing thread T formed on the left side of the sewing needle 101 by the air. Can be moved away from the looper 103 to prevent the blade 102 from being inserted.
That is, at the time of sewing in the folding section B of the waist belt W, the stitch skipping device 100 is operated to prevent the formation of the seam, and it is possible to easily perform the cloth end folding operation performed later.
US Pat. No. 3,065,717

By the way, the air type skipping device 110 has the following problems when, for example, two seams are formed close to the upper or lower portion of the waist belt W.
That is, when forming two stitches arranged side by side, as shown in FIG. 9B, the two needles 101, 101 arranged in close proximity and the two loopers 103, 103 arranged in accordance with the needles 101, 103 are arranged. And are used. In such an environment, when the conventional skipping device 110 for performing the skipping is used, the sewing thread T1 of the sewing needle 101 adjacent to the skipping device 110 is positioned to avoid the sword tip 102 of the looper 103 as in the conventional case. The sewing thread T2 of the sewing needle 101 that is far from the skipping device 110 can be moved to a position that sufficiently avoids the sword tip 102 of the looper 103 because the front sewing needle 101 blocks air. There was a case that could not be made.
For this reason, in the conventional skipping device 110, when the stitches are arranged close to each other, there is a disadvantage that the skipping of one stitch may not be performed satisfactorily.

  An object of the present invention is to perform skipping satisfactorily even when a plurality of stitches are performed side by side.

  According to the first aspect of the present invention, a plurality of loopers for capturing a loop of a sewing thread from a sewing needle that moves up and down with a sword and inserting the looper thread from a sewing needle that moves up and down, and capturing the looper thread from the sword tip of each looper. A stitching device for a chain stitch sewing machine that performs sewing with at least two sewing needles, and includes a shielding position that shields the tip of each projection from each looper and each of the loopers. A configuration is adopted in which a shielding member provided so as to be switchable to a retracted position where the protrusion is not shielded and an operating means for switching the shielding member between the shielded position and the retracted position are provided.

  The “shielding” by the shielding member does not mean visually shielding, but means that the tip portions of the plurality of protrusions prevent the looper thread passed through the looper from being captured.

  The invention described in claim 2 has the same configuration as that of the invention described in claim 1, and maintains the looper yarn of the looper advanced toward each sewing needle in a state along the forward movement direction of the looper. It has a structure with a guide.

  The invention according to claim 3 has the same configuration as that of the invention according to claim 1 or 2, and the shielding member has a plurality of shielding parts, and a part of the shielding parts has a position between the projections. It is configured to be a retreat position.

  “The position between the projections as the retracted position” means that the shielding portion is arranged to shield the position between the projections when viewed from the looper side (for example, in FIG. 5). Shield arrangement).

The invention described in claim 1 will be described. In chain stitching, the sewing machine has at least two sewing needles lowered, and a plurality of looper sword tips corresponding to each sewing needle are individually inserted into the loop of the sewing thread, and each protrusion is individually looped from each sword tip. And form a loop. Then, the respective sewing needles lowered again are inserted into the loops of the looper threads, and two or more stitches are formed by alternately inserting the loops of the sewing thread and the loops of the looper thread.
The skipping device makes the shielding member stand by at the retracted position during normal sewing, and does not prevent each protrusion from capturing each looper thread. Then, when performing the skipping, the operating means switches the position of the shielding member from the retracted position to the shielding position, and shields the tip of each protrusion from the looper. As a result, the shielding member is interposed between the looper and the tip of each protrusion, thereby preventing the looper yarn from being captured. As a result, the loop of the looper thread is inserted in the loop of the sewing thread, but the loop of the sewing thread is not inserted in the loop of the looper thread. The sewn products that are not formed and sewn together can be easily separated from each other.

In this way, in the invention described in claim 1, since a plurality of projections are shielded to skip the eye, even if a plurality of sewing needles are arranged close to each other as in the prior art, it is possible to cope with it. If all the projections are shielded, it is possible to carry out the skipping more reliably.
In addition, when air is used as in the prior art, the closer the sewing needles are, the worse the contact of the air is and causes skipping defects. However, in the configuration of the present invention, the sewing needles are densely arranged. When the loopers are densely arranged and the loopers are densely arranged, the projections are densely arranged, so that the projections can be shielded more easily and reliably, and the stitches closer to the sewing needle are more suitable. It can be said that it is a skip device.

  The invention according to claim 2 is provided with a looper yarn guide for maintaining each looper yarn in a state along the forward movement direction of the looper. Therefore, after the looper advances, the looper yarn is caught by each protrusion and pulled in a direction crossing the forward direction. This can be prevented more effectively, and the skipping can be performed more stably.

  In the invention according to claim 3, the distance between the shielding portion and the projection when the shielding portion is in the retracted position can be made close by setting each shielding portion between the projection and the projection, and switching to the shielding position is possible. In this case, the moving distance can be reduced. As a result, it is possible to reduce the burden on the drive source of the operating means and speed up the switching.

(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 erected from a bed portion 51 located at the lower portion of the frame and extending along the Y-axis direction, and one end portion of the bed portion 51. A standing torso part 52 and an arm part 53 extending from the upper end part of the standing torso part 52 in the same direction as the bed part 51 are provided.
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. Therefore, in such a case, by adjusting the loop amount K of the looper 15 to be small, the sword tip 15a can reach 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. 10B), 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 amount of burr 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.
The spreader 30 is held by a reciprocating mechanism and is switched between a standby position and an 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 pawls 31 of the spreader 30 extends in the cloth feeding direction along the X-axis direction, and the four pawls 31 at the standby position are respectively outlets of the insertion holes 15c of the four loopers 15. It is arranged on the rod-shaped portion 32 so as to be on the left side in FIG. Further, in the operating position, the claw 31 moves from the standby position to the right in FIG. 5, and each claw 31 moves to at least the right side of the needle drop position of each sewing needle 12.

  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 of the main configuration around the looper during the skipping operation as viewed from above, FIG. 7 is a side view of the main configuration around the looper during the skipping operation, and FIG. 8 is the entire skipping device. FIG.
As shown in FIGS. 5 to 8, the skipping device 40 is supported by the looper 15 so as to be switchable between a shielding position that shields the tip of each claw 31 and a retracting position that does not shield. 41 and an operating means 42 for switching the shielding member 41 between a shielding position and a retracted position.

  The shielding member 41 has a U-shaped cross-section by integrally connecting three flat plates respectively facing the upper surface, lower surface, and rear surface (the surface opposite to the surface on which the claw 31 is provided) of the rod-shaped portion 32 of the spreader 30. In this state, the rod-shaped portion 32 is supported so as to be movable along the longitudinal direction (Y-axis direction) of the rod-shaped portion 32 with the rod-shaped portion 32 held inside.

Further, on the flat plate portion facing the lower surface of the rod-shaped portion 32 of the shielding member 41, shielding plates 41a as shielding portions extending in the same direction as the protruding directions of the respective claws 31 are formed in two places. ing.
As shown in FIGS. 6 and 7, each shielding plate 41 a is extended to a length that shields each claw 31 to the tip as viewed from at least each looper 15 side.
Each shielding plate 41a is set to a width that can simultaneously shield at least two claws 31 that are close to each other in the Y-axis direction, as shown in FIG. As described above, the spreader 30 moves from the standby position to the operating position in the Y-axis direction. However, the spreader 30 is set to a width that can be shielded regardless of whether the two claws 31 are in the standby position or the operating position. Yes.
Further, as shown in FIGS. 5 and 6, in the spreader 30, the second claw 31 and the third claw 31 from the left among the four claws 31 are arranged apart from each other. Each shielding plate 41a has a width in the Y-axis direction that is smaller than the distance between the second claw 31 (shown by a solid line) in the operating position and the third claw 31 in the standby position. Is set to
By setting the width in the Y-axis direction of each shielding plate 41a within the above range, when skipping is not performed (when in the retracted position), one shielding plate 41b is placed in close proximity to the two shielding plates 41b. It can arrange | position in the area | region between the nail | claw 31 and the remaining two nail | claws 31 (state of FIG. 5). That is, switching from the retracted position to the shield position is possible by moving to the two adjacent claws 31, so that switching can be performed with a small movement distance.

Further, the looper thread L of the looper 15 that has advanced toward the sewing needles 12 corresponding to the two loopers 15 individually corresponds to the forward end movement direction of the looper 15 ( A looper yarn guide 41b that is maintained in a state along the X axis direction) is formed.
The looper yarn guide 41b is a substantially semi-circular cutout, thereby more effectively preventing the looper yarn guide 41 from being caught by the pawl 31 of the spreader 30 and pulled toward the Y-axis direction after the looper 15 is advanced. Therefore, it is possible to skip the eyes more stably.
In addition, by forming the looper yarn guide 41b from a notch, it is easier to process compared to the case where a guide member is newly provided, so that productivity can be improved. Further, it is possible to prevent the looper yarn L from being sandwiched between the looper 15 and the shielding plate 41a and to protect the looper yarn L. The cutout shape is preferably a smooth shape with no corners (substantially arcuate in this embodiment).

The actuating means 42 holds one end portion of the shielding member 41 and is supported by the bed portion 51 so as to be able to reciprocate along the Y-axis direction, and the holding member 43 at two positions along the Y-axis direction. And a solenoid 44 for switching.
The operating shaft 44a of the solenoid 44 performs a switching operation between a forward position and a backward position, and its operation range is set so that the shielding member 41 is positioned at the shielding position at the forward position and the retracted position at the backward position. ing.

(Description of the operation of the chain stitch machine)
An example will be described in which sewing is performed with the four sewing needles 12 using the above-described waist belt W (see FIG. 10) 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 solenoid 44 is controlled in advance to the retracted position to control the shielding member 41 at the retracted position (state shown in FIG. 5).
Then, each sewing needle 12, each looper 15, and spreader 30 operate synchronously 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, so that 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 solenoid 44 is moved to the forward position, and operation control for positioning the shielding member 41 at the shielding position is performed (state of FIG. 6).
As a result, each looper 15 inserts the looper thread L into the loop of the sewing thread T of the lowered sewing needle 12, but the shielding portion 41 a is interposed between each looper 15 and each pawl 31 of the spreader 30, and the looper thread L Will be blocked. 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, and the solenoid 44 is moved to the retracted position, and operation control for positioning the shielding member 41 at the retracted position 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 shielding member 41 is located at the retracted position, it does not interfere with the sewing, and 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)
In this way, in the chain stitch sewing machine 10, the skipping is performed by shielding the plurality of claws 31 of the spreader 30 by the shielding member 41 of the skipping device 40, so that the loop of the sewing thread is prevented from being captured using air. As in the case where the plurality of sewing needles 12 are arranged side by side, it is possible to perform the skipping more reliably without causing a skipping defect.

  Further, the skipping device 40 is configured such that the one shielding plate 41a of the shielding member 41 sets the position between the two claws 31 and 31 and the other two claws 31 and 31 as the saving position. It is possible to make the distance between the shielding plate 41a and the claws 31 and 31 to be shielded close to each other, and to reduce the movement distance when switching to the shielding position. As a result, it is possible to reduce the burden on the solenoid 44 of the actuating means 42 and speed up the switching.

(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 number of individual shielding plates 41a of the shielding member 41 and the number of claws shielded by one shielding plate 41a are not limited to the example of the embodiment.
Further, the shielding plate 41 of the shielding member 41 is desirably thin, but may be a mesh shape, a fence shape, or a rod shape. Moreover, you may have flexibility.

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 the perspective view which looked at the main structure around the looper under execution of skipping from the upper part. It is a side view of the main composition around a looper in execution of skipping. It is a perspective view which shows the whole skipping apparatus. 9A is a front view of a looper and a skipping device when one looper is used in a conventional chain stitch sewing machine, and FIG. 9B is a looper and a skipping device when two loopers are used. FIG. FIG. 10A is an explanatory view of a waist belt in jeans, and FIG. 10B is an explanatory view of a sewing section of the waist belt.

Explanation of symbols

10 Sewing machine 12 Sewing needle 15 Looper 15a Blade tip 30 Spreader 31 Claw (protrusion)
40 Blind device 41 Shield member 41a Shield plate (shield part)
41b Looper thread guide 42 Actuating means L Looper thread T Sewing thread

Claims (3)

A plurality of loopers for capturing a loop of a sewing thread with a sword tip from a sewing needle that moves up and down by swinging operation and inserting a looper thread, and a plurality of loopers for capturing the looper thread from the sword tip of each looper and forming a loop A stitching device for a chain stitch sewing machine that includes a projection and performs sewing with at least two sewing needles,
A shielding member provided so as to be switchable between a shielding position that shields the tip of each projection from each looper and a retracted position that does not shield each projection;
An operation device for switching the shielding member between a shielding position and a retracted position is provided.   The loop stitcher for a chain stitch sewing machine according to claim 1, further comprising a looper thread guide for maintaining the looper thread of the looper advanced toward each sewing needle in a state along the forward movement direction of the looper. The shielding member has a plurality of shielding parts,
3. The chain stitch sewing machine skipping device according to claim 1, wherein a part of the shielding portions has a retracted position at a position between the protrusions.

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