JPH05200179A - Cutting of thread in sewing machine and its apparatus - Google Patents

Abstract

PURPOSE:To provide a cutting method of threads and a device increaseing an operational efficiency without hindering minimization of a cylindrical bed, by securely cutting off a needle thread and a looper thread in a flat-sewing mechine provided with the cylindrical bed and securely hold the looper thread after cutting. CONSTITUTION:When needles 1,1... position at the lower dead point and an operation rod 2b of a looper controlling the looper thread 2a comes off out of a loop formed by thread needles 1a, 1a,... to be in the indicated (a) condition, the looper thread 2a is cut off at the front end of the operation rod 2b. After that, when the needles 1, 1,... position at the upper dead point and the operation rod 2b of the looper is inserted in the loop formed by the needle threads 1a, 1a,... to be in the shown (c) condition, the needle threads 1a, 1a,... are collected together and pulled out and cut off by a movable knife proceeding in the loop along the operation rod 2b and receding from the loop along the reverse path.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of thread-cutting a needle thread and a looper thread in conjunction with a stop of sewing in a multi-needle flat stitch sewing machine having a tubular bed, and a thread trimmer used for carrying out this method. Regarding the device.

[0002]

2. Description of the Related Art FIG. 1 is an explanatory view showing a sewing process in a multi-needle flat stitch sewing machine. The multi-needle flat stitch sewing machine is provided with a plurality of needles 1, 1 ... Lined up in one direction on the front surface side of a needle plate (not shown) on the bed, and a looper 2 on the back surface side. Sewing is performed on the sewing material A that is fed on the surface of the needle plate in a direction orthogonal to the direction in which the needles 1, 1 ... Are arranged in parallel.

The needles 1, 1 ... Together with the needle threads 1a, 1a inserted in the needle holes at the respective tips as shown in the drawing, move in a predetermined manner so as to penetrate the needle plate in the front and back in conjunction with the feeding of the sewing material A. Move up and down between strokes. Further, the looper 2 is provided with an operating rod 2b through which a looper thread 2a is inserted as shown in the drawing from the end to the tip thereof. The operation of the looper 2 is such that the sewing material A is rotated around a horizontal axis along the feeding direction of the sewing material A. Is a rotational movement within a predetermined angle range that occurs in association with the feeding of the needles, and at this time, the operating rod 2b oscillates along a predetermined circumference centering on the rotation axis, and the needles 1, 1 ... The forward / backward movement is performed along the parallel line.

1 (a) shows a state in which the needles 1, 1, ... Are at the lowest point (bottom dead center) during the moving stroke, and FIG. 1 (c) shows
Similarly, each state is shown at the highest point (top dead center),
Further, FIG. 1B shows a transition state from bottom dead center to top dead center, and FIG. 1D shows a transition state from top dead center to bottom dead center. As is apparent from these, the operating rod 2b of the looper 2 has the needles 1, 1 ...
One advance operation is performed during the upward movement, and one retreat operation is performed during the downward movement, and the sewing material A is fed by needles 1, 1 ...
During the upward movement, that is, every time the transition from FIG. 1 (c) to FIG. 1 (d) occurs, it is intermittently performed every predetermined length.

First, FIG. 1A through FIG.
.., a loop formed by the different needle threads 1a, 1a ... Is formed immediately below the plurality of needles 1, 1 ... As shown in FIG. The operating rod 2b of the looper 2 performing the advancing operation during this period is inserted into the loop together with the looper thread 2a inserted therethrough. As a result, in FIG. 1 (c) where the needles 1, 1 ... Have reached the top dead center, the respective needle threads 1a, 1a ... Are in a state of being collectively captured by the operating rod 2b of the looper 2. ..

On the other hand, FIG. 1 (c) through (d) to (a)
By the time the sewing cloth A is fed during this time, the needle threads 1a, 1a ... Captured by the operating rod 2b of the looper 2 and the looper thread 2a inserted through the operating rod 2b are respectively fed. , Is relatively pulled out by a length corresponding to one feed amount, and at this time, the looper thread 2a is pulled out obliquely from the end of the entangled portion with the needle threads 1a, 1a ... To the tip of the operating rod 2b. Thus, it has a triangular shape as shown in FIG. Then, during this time, the needles 1, 1 penetrating the sewing material A and moving downwards ...
Are sequentially inserted through the apex side portion of the triangle formed by the looper thread 2a and the rectangular portion formed by the needle threads 1a, 1a ... And the looper thread 2a, and as shown in FIG. The looper thread 2a is pulled out from the operating rod 2b of the looper 2 and the looper thread 2a is supported while being inserted into the loop formed by the needle threads 1a, 1a.

By repeating the above operation, parallel stitches formed by the needle threads 1a, 1a are arranged on the front surface side of the sewing material A, and on the back surface side, the needle thread 1a, which protrudes to the same side, is also formed. 1a
The loops of ... Are associated with the looper thread 2a inserted therethrough to form a seam in which the loops are entwined as shown in the drawing. In addition, FIG. 1 shows a sewing configuration in which decorative sewing is also performed on the front side of the sewing material A. The decorative stitch on the front side is
It is formed by the operation of the decorative thread looper 3 which is arranged on the front side of the sewing material A and is interlocked with the vertical movement of the needles 1, 1 ...

In the multi-needle flat stitch sewing machine which constitutes the above-mentioned sewing, in order to improve the efficiency of the sewing work, the needle threads 1a, 1a ... Widely equipped with a thread cutting device for cutting. This thread trimming device has a blade surface facing one side of the passage of the needle threads 1a, 1a ..., A fixed knife fixedly provided on the back side of the needle plate, and the needle threads 1a, 1a while slidingly contacting the fixed knife. It is provided with a movable knife that reciprocates in the arranging direction of 1a.

The movable knife is provided with locking claws that perform a shearing action between the movable knife and the blade surface of the fixed knife at the tip and in the middle thereof, and the needles 1, 1 ... One reciprocating motion is performed with the device stopped near the point. The state of the needle threads 1a, 1a ... and the looper thread 2a near the top dead center is as follows.
As shown in FIG. 1 (c), the forward movement in this state causes the movable knife to move the operating rod 2b into the loop of the needle threads 1a, 1a ... In which the operating rod 2b of the looper 2 is inserted. The looper thread 2a is locked into the locking claw at the tip that comes in from the same side and reaches the vicinity of the tip of the operating rod 2b, and the needle thread 1a on the innermost side is locked into the locking claw in the middle.
Is locked, and after that, it moves backward in the reverse direction and returns to the initial position where the locking claw at the tip overlaps the blade surface of the fixed knife.

Thus, during this return movement, a plurality of needle threads 1a, 1a
... are collectively pulled out by the locking claw in the middle of the movable knife, and the looper thread 2a is pulled out by the locking claw at the tip, and both are cut by shearing with the blade surface of the fixed knife. However, since this returning movement is completed by returning to the initial position, the looper thread 2a pulled out by the locking claw at the tip is held in a sandwiching pressure between the fixed knife and the movable knife even after the cutting, There is no risk of the looper 2 slipping out of the operating rod 2b, and it is not necessary to reattach the looper 2 to the next sewing start.

When the needles 1, 1, ... Are near the top dead center, a thread loosening mechanism (not shown) operates in conjunction with the movement of the needles 1, 1, ..., As described above in connection with the next feeding of the sewing material A. The tension applied to the needle threads 1a, 1a ... And the looper thread 2a is relaxed so as to enable the withdrawal, and the above-mentioned withdrawal for cutting these can be performed without problems.

[0012]

As a multi-needle flat stitch sewing machine, various sewing machines having different bed shapes according to the sewing object have been commercialized. For example, a small size raglan sleeve is sewn. As a target, one provided with a thin cylindrical bed through which the sleeve portion can be inserted is widely used.

However, when the above-described thread trimming device is constructed in a multi-needle flat stitch sewing machine having such a tubular bed, the movable knife and its drive are provided in the bed on the back side of the needle plate where the looper 2 operates. In many cases, it is not possible to secure a sufficient space for the additional configuration of the mechanism, and it is necessary to devise a countermeasure for this.

A thread cutting device disclosed in Japanese Utility Model Laid-Open No. 63-139879 is known as a thread cutting device for application to a sewing machine of this type, that is, a multi-needle flat stitch sewing machine having a tubular bed. There is. This thread trimming device uses a movable knife that is curved like a hook and has one locking claw at its tip, and pivotally supports the vicinity of the proximal end of the movable knife on the downstream side of the needle drop position in the feed direction, While it is swingable around a plane parallel to the needle plate around the pivot axis, the operating end of an actuator such as an air cylinder that moves back and forth in the cylinder axis direction of the bed is engaged near the pivot axis. The movable knife is swung by the operation of the actuator.

The operation of this thread cutting device is performed in a state in which the needles 1, 1, ... Are stopped at the top dead center, similarly to the general thread cutting device described above. Along with its own curve, the movable knife advances,
Needle threads arranged below the needle drop position as shown in FIG. 1 (c).
It enters the loop of 1a, 1a .... At this time, the locking claw at the tip of the movable knife locks the innermost needle thread 1a, and the needle thread 1a, 1a, ...
2a is collectively captured and pulled out, and these needle threads 1a, 1a ...
The looper thread 2a is cut by the movable knife and a fixed knife that is in sliding contact with the end of the retreat path, and is held by sandwiching the knife between both knife.

In this thread cutting device, the movable knife is driven by an actuator that can be appropriately arranged on an extension line in the cylinder axis direction of the bed, and the movable knife curved in an arc shape is provided on the back side of the needle plate. Since only a space which can be swung within a predetermined angle range along the curve is required, the cylindrical bed having a small diameter can be formed with a margin, but it also has the following drawbacks.

That is, the cut needle threads 1a, 1a ... Are both held in a state of being sandwiched between the movable knife and the fixed knife, and the needle threads 1a, 1a. When A is removed, it is pulled out from the constriction site. At this time,
In some cases, the looper thread 2a, which is held by the pressing force, comes out, and the looper thread 2a may come off from the operating rod 2b of the looper 2 at the start of the next sewing. In this case, the stitches cannot be formed, and the sewing operation must be stopped. Therefore, it is necessary to take appropriate measures to prevent the looper thread 2a from coming out of the looper 2.

Further, in a sewing machine equipped with a thin cylindrical bed, the operating range of the looper 2 is limited, and the operating rod 2b having a large curvature as shown in FIG. 1 cannot be employed. The tip of the rod 2b is located below the loop formed by the needle threads 1a, 1a ... Therefore, the tip of the movable knife, which is inserted into these loops as described above, is located above the looper thread 2a extending from the tip of the operating rod 2b, and the needle threads 1a, 1a ... However, the looper thread 2a cannot be locked by the locking claw at the tip.

JP-A-63-214277 and JP-A-63-262
In Japanese Patent No. 182, an arcuate movable knife having a curvature substantially equal to that of the operating rod 2b of the looper 2 and curved in the thickness direction is arranged so as to be swingable coaxially with the rotation axis of the looper 2. Further, a fixed knife is arranged in the middle of this swing path, and the movable knife is caused to make one reciprocating motion with the needles 1, 1 ... Stopped at the top dead center, and the needle threads 1a, 1a. A thread cutting device configured to cut the thread 2a is disclosed.

In this structure, since the movement path of the movable knife is along the operating rod 2b of the looper 2, it is possible to reliably capture the looper thread 2a at the tip of the operating rod 2b. , Needle thread 1 by removing sewing material A
When pulling out a, 1a, ..., the looper thread 2a, which is held by the clamping force, comes out, and there is a problem that the next sewing work is hindered.

The present invention has been made in view of the above circumstances, and makes it possible to reliably cut the needle thread and the looper thread in a flat stitch sewing machine having a tubular bed, and to retain the looper thread after cutting. An object of the present invention is to provide a thread cutting method for a sewing machine which can be surely performed and does not hinder the thinning of a tubular bed, and a thread cutting apparatus used for the execution.

[0022]

SUMMARY OF THE INVENTION A thread cutting method for a sewing machine according to the present invention comprises a cylindrical bed for feeding in the axial direction, and a plurality of needles that vertically move by penetrating the needle plates on the bed to the front and back. ,
And a looper on the back side of the needle plate that moves back and forth according to the vertical movement of each needle, and a needle thread that moves up and down together with each needle, and a looper thread that is entangled with each needle thread by the operation of the looper. In a thread cutting method of a sewing machine that cuts inside a shaped bed, each of the needles is stopped near the bottom dead center to cut the looper thread, and then each of the needles is stopped near the top dead center to The feature is that the needle thread is cut at a time.

The thread cutting device for a sewing machine according to the present invention is
A first fixed knife with its blade surface facing the working end of the looper in the retracted state, a second fixed knife with its blade surface facing the vertical movement path of each needle, and each needle The first reciprocating operation is performed in response to the stop in the vicinity of the bottom dead center, the looper thread is captured and drawn out in the vicinity of the working end of the looper, and the looper thread is cut between the first fixed knife and the first holding knife. The movable knife and the needles reciprocate in response to a stop near the top dead center of the needles, enter the loop formed by the plurality of needle threads at the time of forward movement, and then return to move the needle threads. A second movable knife which is captured and pulled out in a lump and is cut between the second fixed knife and the second fixed knife, and further, the looper thread during the operation of the first movable knife. It is characterized in that it is provided with a means for releasing the tension.

[0024]

In the present invention, when the needles of the sewing machine stop near the bottom dead center and the operating rod of the looper is in the retracted state, the looper thread pulled out from the tip of the operating rod, that is, the operating end of the looper is removed. The first movable knife captures and pulls out the first
The needle is cut and held between the fixed knife and the needle, then the needles of the sewing machine stop near the top dead center and the operating rod of the looper is inserted into the loop formed by the needle threads. At some time, the second movable knife enters into these loops, catches and pulls out the needle threads all at once, and cuts between the second fixed knife and the second fixed knife.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. FIG. 2 is a plan view of a bed portion of a multi-needle flat stitch sewing machine equipped with a thread cutting device for a sewing machine according to the present invention (hereinafter referred to as a device of the present invention), and FIG. 3 is a side view taken along line III-III of FIG. is there.

The apparatus of the present invention is applied to a multi-needle flat stitch sewing machine having a bed 4 having a thin cylindrical shape as shown in the drawing. The bed 4 is a sewing machine main body B shown by a chain double-dashed line in the figure.
From a base 40 extending in parallel to the rear of the sewing machine and projecting forward with the cylinder axis orthogonal to the base 40. Further, a sewn portion C, which is covered with the looper 2 and is provided with a looper 2 and a feeding mechanism for the sewing material, is formed inside thereof. In order to prevent the drawing from becoming complicated, the looper 2 and the feed mechanism are not shown in FIG. 2, the looper 2 is schematically shown as a box in FIG. 3, and the feed mechanism is not shown. ..

The device of the present invention comprises first and second movable knives 11 and 12 arranged on the sewn portion C, and fixed knives 13 and 14 (see FIG. 4) paired with the movable knives 11 and 12, respectively. All of these are attached to the back surface of the needle plate 5 that covers the upper surface of the sewing portion C. FIG. 4 is an exploded perspective view showing how the respective scalpels are attached to the needle plate 5.

As shown in the figure, the needle plate 5 is a flat plate having a planar shape corresponding to the planar shape of the tip of the bed 4, and the needles 1, 1 ... The number of needle drop holes 5a, 5a, ... Corresponding to the number of needle drop holes 5a, 5a ... Are formed side by side in one direction, and a pair of long holes 5b, 5b are formed on both sides of the needle drop holes 5a, 5a. Is formed,
Furthermore, two bolt holes 5c, 5c are formed in the peripheral portion, and as shown in FIG. 2, the bed 4 is secured by tightening fixing bolts (not shown) inserted into the bolt holes 5c, 5c, respectively. Further, it is positioned and fixed so that the cylinder axis direction thereof is orthogonal to the juxtaposed direction of the needle drop holes 5a, 5a ....

The long holes 5b and 5b are provided to expose the feed dogs 6 and 6 (see FIG. 6) of the feed mechanism built in the bed 4 to the upper surface of the needle plate 5, and on the needle plate 5. Sewing material A
(Refer to FIG. 1), the long holes 5b,
A feed along the longitudinal direction of 5b is applied, and during this feed, the sewing material A moves up and down on the throat plate 5 and the needle drop hole 5
Needles 1, 1 ... Inserted through a, 5a ... (See FIG. 1)
And the operation of the looper 2 that occurs in the bed 4 in synchronism therewith, so that a seam as shown in FIG. 1 is formed.

As shown in the figure, the first movable knife 11 is a guide hole which is a pair of elongated holes which are parallel to each other and are displaced in the longitudinal direction.
1a, 11a and a thin flat plate-shaped support part consisting of these edging parts, and the edging part of one guide hole 11a to the other guide hole.
11a extends in the opposite direction and has a female portion having a locking claw 11b at the extended end, and the end of the edging portion of the other guide hole 11b, that is, the end portion on the opposite side to the extending direction of the female portion. In addition, an engaging projection 11c in the form of a short round bar is provided so as to project.

The second movable knife 12 is connected to a support portion formed by radially extending the edging ring of the bearing hole 12a having a circular cross section, and bent at a predetermined angle in the same plane at the extended end to be continuous. An arm portion and a female portion that is continuously provided in the same plane at the tip of the arm portion to form an arc centered on the bearing hole 12a and has a locking claw 12b protruding inward at the tip. At the same time, the engaging projection 12c in the shape of a short round bar is provided in the middle of one surface of the support portion.

The throat plate 5 has a thick portion thicker than the other portion on the rear end, that is, on one side of the base end of the bed 4 by thickening the back surface. The long hole in the meat
A pair of screw holes 50, 50 are formed penetratingly in a direction parallel to the longitudinal direction of 5b, that is, in the feeding direction of the sewing material A, and the first movable knife 11 functions as a spacer. Fixing screws 51 and 51 are inserted into the guide holes 11a and 11a respectively through the separate washers 52 and 52, and these are formed into the screw holes.
It is attached by screwing it into each of 50 and 50.

By this attachment, the first movable knife 11 is
It is possible to slide in the longitudinal direction of the guide holes 11a, 11a within these length ranges, and these guide holes 11a, 11a connect the fixing positions of the fixing screws 51, 51 that perform the guiding action. Straight line,
That is, since it is inclined with respect to the longitudinal direction of the long hole 5b in the needle plate 5, the locking claw 11b at the tip of the first movable knife 11 is thickened with respect to the back surface of the needle plate 5 by the sliding. In a plane separated by the added amount of meat to the meat portion, it advances toward one side of the elongated hole 5b along a straight path inclined with respect to the elongated hole 5b, and also retreats along the same path. Make an action.

The movement path of such a movable knife 11 is shown in FIG.
As shown in (a), a plurality of needles 1, 1 ... Are near the bottom dead center, and the tip of the operating rod 2b of the looper 2 in a state of being pulled out from the loop formed by the needle threads 1a, 1a. Is made to face the looper thread 2a pulled out from this tip, and the looper thread 2a is set so that it can be locked by the locking claw 11b of the movable knife 11 in the advanced state.

A first fixed knife 13 which is paired with the movable knife 11 is attached to the middle of the movement path of the movable knife 11. The fixed knife 13 has a planar shape corresponding to each other, and as shown in the drawing, a knife piece 13a having a blade portion on one side edge, and a spring configured to bend the same side edge portion to perform a spring action. Piece 1
3b, and these and the pressing piece 13c through the spacer piece 13d of a predetermined thickness as shown in the drawing, the movable knife on the back surface of the needle plate 5.
The mounting side of 11 and the side of the same side are overlapped, and the fixing screws 53, 53 ... Inserted in the spacer piece 13d, the female piece 13a and the spring piece 13b from the front side of the needle plate 5 are used as the pressing piece 13c. It is configured to be screwed and fixed into each of the formed screw holes.

The blade surface at the tip of the female piece 13a fixed in this way is arranged so as to face the tip of the operating rod 2b of the looper 2 with the plurality of needles 1, 1 ... The lower surface of the piece 13d is an inclined surface for ensuring the cutting of the needle threads 1a, 1a ... Between the knife piece 13a and the movable knife 11 as will be described later. The above-described forward / backward movement of the first movable knife 11 is performed while being sandwiched between the female piece 13a and the spring piece 13b, and the looper thread 2a locked by the locking claw 11b during the retracting operation is The knife piece 13a is cut at a sliding contact portion with the blade surface of the tip, and this cut end is held by sandwiching between the lower surface of the locking claw 11b and the spring piece 13b.

Further, the needle plate 5 has a pair of screw holes 54, 54 ... Formed along the front side of the elongated hole 5b on the same side as the mounting side of the first movable knife 11 and the length of the other side. The second movable knife 12 is provided with a screw hole 55 formed behind the hole 5b, and the second movable knife 12 has a fixing screw 56 inserted through the bearing hole 12a via a washer 57 acting as a spacer. It is attached by screwing it into the hole 55.

By this attachment, the second movable knife 12 is
It is possible to swing about the support hole 12a around the fixing screw 56 as a pivot. At this time, the locking claw 12b at the tip traverses directly below the needle drop holes 5a, 5a ... In the juxtaposed direction. As shown in FIG. 1 (c), the needle rods 1a, 1a ... Underneath the needle drop holes 5a, 5a ... Enter the loop formed by the needle threads 1a, 1a. Thread 1a, 1a
Lock and pull out all at once.

The second fixed knife 14 paired with the second movable knife 12 has a knife piece 14a having a blade portion at the side edge of one end thereof.
And a spring piece 14b whose end portion is bent so as to perform a spring action. These pieces are aligned and superposed on each other in a plan view, and two fixing screws 5 are inserted from the lower side.
8 and 58 are screwed into and fixed to the screw holes 54 and 54, respectively. At this time, the blade of the knife piece 14a is
The needles 1, 1 ... Are faced to the side where the needles 1, 1 ... Are arranged in parallel, that is, on the movement path of the second movable knife 12.

That is, the locking claw 12b of the second movable knife 12 is
The needle threads 1a, 1a ... that are pulled out by being engaged with the retracting claw 12b when the retaining claw 12b is retracted by performing the advance / retreat operation described above while being sandwiched between the knife 14a and the spring 14b are 14a is cut at the sliding contact portion with the blade surface of the tip.

The above-described operation of the first and second movable knife 11, 12 is the forward / backward movement of each of the separate air cylinders 21, 22 fixed to the rear portion of the bed 4, as shown in FIGS. Is done accordingly. These air cylinders 21 and 22 are fixed so that their output ends face the tip of the bed 4 and are parallel to the cylinder axis of the bed 4, and these output ends 21a and 22a are different from each other. The base ends of the connecting rods 23 and 24 are engaged with each other.

As shown in FIG. 2, the connecting plate 23 is a narrow flat plate that approaches the bed 4 from the output end 21a of the air cylinder 21 and further extends forward along the side portion of the bed 4. An elongated hole 23a that is inclined with respect to the cylinder axis of the bed 4 is formed at the tip end of the bed 4, and an engaging protrusion 11c protruding from the rear end of the first movable knife 11 is fitted into this elongated hole 23a. There is.

The other connecting plate 24 is, as shown in FIG.
The air cylinder 22 is attached to a flat thin plate having a linear shape extending toward the tip at the center in the width direction near the upper surface of the bed 4.
The base end portion that is bent toward the output end 22a and the tip end portion that is inclined at an appropriate angle with respect to the cylinder axis are connected to each other. An inclined elongated hole 24a is formed, and the engaging protrusion 12c projecting from the second movable knife 12 is fitted into the elongated hole 24a.

FIG. 2 shows a state in which the air cylinders 21 and 22 are both in the retracted position. When the air cylinder 21 makes one forward / backward movement from this state, the engagement is first performed in accordance with the advance. The projecting portion of the protrusion 11c is pushed forward through the connecting plate 23, and the first movable knife 11 is guided by the guide holes 11a, 11a and the fixing screws 51, 51, so that the bed 4 The air cylinder moves forward in a direction approaching the center of the bed 4 along a straight line inclined with respect to the cylinder axis, and the next air cylinder
In response to the retreat operation of 21, the retreat operation is performed in the opposite direction on the straight line.

When the other air cylinder 22 makes one forward / backward movement, first, the engaging protrusion 12c is moved in accordance with the advance.
The projecting portion of is pushed forward through the connecting rod 24, and the second movable knife 12 swings around the fixing screw 56 inserted in the bearing hole 12a as the pivot axis, and the locking claw at the tip. 12b performs the advancing operation described above, and performs the retreating operation in the opposite direction according to the retreating operation of the next air cylinder 22.

Air cylinders 21 and 22 that operate as described above
A yarn winding cam device 7 whose configuration is shown in FIG. 3 is formed in the hollow portion 41 of the base 40 on the side of the fixed position. The yarn winding cam device 7 is a known device that adjusts the amount of feeding the looper yarn 2a according to the above-described operation of the looper 2, and includes a gantry 70 mounted in the hollow portion 41 in a substantially horizontal direction, and a frame as illustrated. It has a plane shape and is provided with a thread take-up cam 71 which is rotationally driven around one axis at the bottom of the gantry 70. A pair of cam thread passages 7
As shown in FIG. 3, the former has one threading hole on the axis of the thread take-up cam 71, and the latter has an elongated hole along the upper surface of the gantry 70. ..

On both sides of the hollow portion 41, one ends of thread guide tubes 42 and 43 are opened, and one thread guide tube 42, a part of which is shown in FIG. 2, extends toward the sewing machine main body B. The other yarn guide tube 43 extends along the side surface of the bed 4 to the position where the looper 2 is disposed below the needle plate 5. A thread hooking portion 74 is fixed on the base 70 of the thread take-up cam device 7 so as to face the open end of the thread guide tube 42 from the sewing machine main body B, and the thread guide tube 43 toward the bed 4 is fixed. At the open end, a thread hooking portion 75 having a shape in which the base portion is fixed to the upper surface of the base 40 and the tip is suspended in the hollow portion is exposed.

The thread take-up cam device 7 includes a sewing machine main body B.
The looper thread 2a is supplied from the thread guide tube 42 to the looper thread 2a. The looper thread 2a is first inserted into the thread hooking portion 74 and the cam thread path 72 in this order, and the looper thread 2a is projected on the upper part of the frame 70. It is bridged over the edge, further inserted through the cam yarn path 73 and the yarn hooking portion 75 in this order, and supplied to the looper 2 via the yarn path tube 43. The thread take-up cam 71 of the thread take-up cam device 7 is adapted to rotate in synchronization with the rotation of the looper 2, and the looper thread 2a laid over the upper edge is tense when passing through the convex portion due to the rotation, On the contrary, as a result of loosening when passing through the concave portion, the looper thread 2a in an amount corresponding to the operation of the looper 2 is delivered without excess or deficiency.

As shown in FIG. 3, the frame 70 of the yarn reeling cam device 7 that operates in this manner is mounted between the protrusions 44 and 45 that project inside the cavity 41 so as to face each other. It is not fixed to, but is pivotally supported by one protrusion 44 so as to be swingable around a horizontal axis along one peripheral edge, and the other protrusion 45.
Merely functions as a stopper that restrains this swing. That is, the gantry 70 can be swung only in the direction in which the protrusion 45 side moves upward, and the air cylinder 8 serving as a drive source for this swing is arranged on the rear side of the base 41 in the advancing direction of the output end 8a. Is fixed so that it faces downward.

Inside the cavity 41, a swing arm 80 having an L-shaped planar shape is pivotally supported at a bent portion thereof slightly below the protrusion 44, and swings in a substantially vertical plane. It is attached freely. One end of the swing arm 80 is a hollow portion from a through hole 46 that penetrates the back wall of the base 40 at a corresponding position.
It is made to project to the outside of 41, and this projecting end is engaged with the output end 8a of the air cylinder 8. The other end of the swing arm 80 is projected on the upper surface of the gantry 70,
The bracket 76 is erected on the upper surface of the corresponding position.

With the above construction, when the air cylinder 8 advances, the swing arm 80 swings by pushing down the end portion on the side engaging with the output end 8a, and this swing causes the bracket 76 to move.
Since the end portion on the engagement side with and makes a circular arc movement toward the rear, the gantry 70 is pulled rearward from the standing position of the bracket 76,
Swing in the direction to lift the protrusion 45 side. As a result, FIG.
As shown in FIG. 5, the projecting height of the thread reeling cam 71 on the gantry 70 is reduced, and the looper thread 2a is placed between the cam thread paths 72 and 73 on both sides regardless of the rotating position of the thread reeling cam 71. Then, the tension is released, and the looper thread 2a is slackened. Within this slackness, the looper thread 2a can be pulled out without resistance from the upstream side, that is, the looper 2 side.

6 to 11 are explanatory views of the thread cutting operation by the device of the present invention configured as described above, and FIGS.
[Fig. 4] is a time chart showing the operation timing of each unit. 12 shows the case where the decorative sewing of the upper surface of the sewing material A by the decorative thread looper 3 shown in FIG. 1 is not carried out, and FIG. 13 shows the case where the decorative sewing is carried out. First, the time shown in FIG. The operation will be described according to the chart.

The instruction for thread trimming after the completion of sewing is performed, for example, by operating a foot pedal (not shown). First, when the operation of the sewing machine is stopped by releasing the foot pedal, as shown in FIG. 12, a signal for forcibly moving the hands 1, 1 ... From the current position to the bottom dead center is issued, and the preset waiting time is set. The looper thread trimming command is issued after the elapse of T ₁ .

As a result, as shown in FIG. 6, the needles 1, 1, ...
Are inserted into the respective needle drop holes 5a, 5a ... Of the needle plate 5, and the operating rod 2b of the looper 2 is pulled out from the loop formed by the needle threads 1a, 1a ... As described with reference to FIG. At this time, the looper thread 2a pulled out from the tip of the operating rod 2b faces the tips of the first movable knife 11 and the first fixed knife 21, which are formed on the back side of the needle plate 5 as described above.

The waiting time T ₁ is set in consideration of the time required for the needles 1, 1 ... To reach the bottom dead center and the time required for confirming the stop after reaching the bottom dead center. According to the instruction, the first movable knife 11 operates to cut the looper thread 2a. This looper thread trimming command is specifically a signal that commands the air cylinder 21 to advance a predetermined amount and to the air cylinder 8 that is the swing source of the gantry 70 of the yarn reeling cam device 7. Is.

That is, in response to the advance of the air cylinder 21 in accordance with the looper thread cutting command, the first movable knife 11 advances toward the looper thread 2a in the above-described state, and as shown in FIG. The pawl 11b stops at a position where it passes over the looper thread 2a. Further, in response to the advance of the air cylinder 8 performed during this period, the rack 70 of the yarn winding cam device 7 is in the inclined state shown in FIG. 5, and the looper yarn 2a can be pulled out.

Thereafter, the first movable knife 11 retracts in response to the retracting of the air cylinder 21 accompanying the stop of the looper thread trimming command, and at this time, the locking claw 11b at the tip end is moved as shown in FIG. The looper thread 2a existing in the retreat path is captured, and this looper thread 2a is drawn into a position where it slides in contact with the blade surface of the first fixed knife 13 and cut at that position. The end of the cut looper thread 2a is, as described above, the spring piece 13b of the fixed knife 13 and the movable knife.
It is held between 11 and the upper surface. When the looper thread 2a is cut in this manner, the operating rod 2b of the looper 2 cuts the needle thread 1a.
Possible while the looper thread 2a pulled out of the loop formed by a, 1a, and pulled out from the tip of the operating rod 2b faces the tips of the first movable knife 11 and the first fixed knife 21. This condition is not limited to the case where the needles 1, 1 ... Strictly coincide with the bottom dead center, but occurs in the vicinity of the bottom dead center, so that the looper thread cutting command is issued before the command is issued. The forced movement of the needles 1, 1 ... May be performed as long as it moves to the vicinity of the bottom dead center.

As described above, in the device of the present invention, the needle 1,
1 is near the bottom dead center, and the operating rod 2b of the looper 2 is the needle thread 1
Looper thread 2 when retracted from the loop of a, 1a ...
It is designed to disconnect a. In this state,
As shown in FIG. 1A, the looper thread 2a is located away from the loop of the needle threads 1a, 1a ...
It is possible to reliably capture the 2a and subsequently cut it, and it is possible to hold the cut looper thread 2a alone. Further, the looper thread 2a being normally sewn is in a tensioned state near the bottom dead center, but when a looper thread trimming command is issued, the looper thread 70 of the gantry 70 of the thread reeling cam device 7 which is generated as the first movable knife 11 advances. Since it is relaxed by tilting, the cutting can be performed more reliably.

After the looper thread trimming command is stopped, a signal for forcibly moving the needles 1, 1 ... To the top dead center is issued after waiting for a preset waiting time T ₂ , and further preset. needle thread cutting instruction is issued after waiting for the waiting time T _3.

The waiting time T ₂ is the time required for the retracting operation of the air cylinder 21 that occurs after the looper thread trimming command is stopped, in other words, the looper thread 2a is reliably cut off by retracting the first movable knife 11. 9 is set according to the movement command issued after that, that is, in accordance with the movement command issued after the looper thread 2a is reliably cut. As described above, the needles 1, 1 ... Move upward, reach the top dead center, and stop. When the waiting time T ₂ is set too short or not set, the operating rod 2b of the looper 2 interlocked with the upward movement of the hands 1, 1 ... It is important to properly set the waiting time T ₂ because one movable knife 11 collides with the other and one or both of them may be damaged.

Further, the waiting time T ₃ is set in consideration of the time required for the needles 1, 1 ... To reach from the bottom dead center to the top dead center and the time required to confirm the stop after reaching. According to the needle thread cutting command issued thereafter, the second movable knife
12 operates and the needle threads 1a, 1a ... Are cut. Specifically, the needle thread cutting command is a signal that commands the air cylinder 22, which is the drive source of the second movable knife 12, to advance a predetermined amount.

When the needles 1, 1 ... Are at top dead center, under the needle plate 5, as shown in FIG. 1 (c), the needle threads 1a, 1a.
The operating rod 2b of the looper 2 is inserted in the loop formed by the above. Therefore, when the air cylinder 22 advances according to the needle thread cutting command, the support hole is formed in the second movable knife 12.
When the swing motion around 12a is performed, the movable knife
The arcuately curved female portion 12 is inserted from the same side as the operating rod 2b into the loop of the needle threads 1a, 1a ... In the above-mentioned state, and as shown in FIG. Stops at the position beyond the innermost needle thread 1a.

Thereafter, the second movable knife 12 performs a swinging motion in the opposite direction in response to the withdrawal of the air cylinder 22 accompanying the stop of the needle thread cutting command, and at this time, the locking claw 12b at the tip end is moved to the position shown in FIG. , The needle threads 1a, 1a ... Arranged in the retreat path are sequentially captured, and the needle threads 1a, 1a ... Are drawn into the sliding contact position with the blade surface of the second fixed knife 14 and cut at the position. The cut needle thread 1a,
1a ... Is left without being held between the fixed knife 14 and the movable knife 12. It should be noted that the needle threads 1a, 1a thus performed
For cutting, the operating rod 2b of the looper 2 is inserted into the loop formed by these needle yarns 1a, 1a, and the needle yarns 1a, 1a ... Are inserted between the operating rod 2b and the needles 1, 1. This is possible in a stretched state, and such a state occurs not only when the needles 1, 1 ... Strictly coincide with the top dead center, but also occurs near this top dead center. The forced movement of the needles 1, 1 ... Prior to the generation of the thread trimming command may be any movement that moves the needles to the vicinity of the top dead center.

As described above, in the device of the present invention, the needle 1,
1 is near the top dead center, and the operating rod 2b of the looper 2 is the needle thread 1
When it is in the state of entering the loop of a, 1a ..., the needle plate 5
Only the needle threads 1a, 1a, ... Which can be reliably captured by the second movable knife 12 that swings in the plane of are cut.

After the needle thread trimming command is stopped, a signal (lifting command) for moving the presser foot of the sewing material A upward after waiting for a preset waiting time T ₄ is further preset. cut after waiting for the waiting time T ₅ the needle thread 1a,
An operation command is issued to each wiper that operates to flip up the needle 1.1 side of 1a on the needle plate 5, and a series of thread cutting operations is completed.

The standby time T ₄ is the time required for the retreat operation of the air cylinder 22 that occurs after the stop of the needle thread cutting command, in other words, the return movement of the second movable knife 12 causes the needle threads 1a, 1a to move. ... time to reliable cutting is performed, and Yes set in anticipation of the time for confirming the operation end, also the waiting time T _5, the sewing workpiece a from the bed 4 after increase of the presser foot It is set in anticipation of the time required for removal. Any appropriate setting of these times is necessary to enable reliable and safe removal of the sewing material A.

The removal of the sewing material A is performed after the presser foot is raised and before the wiper operates, and at this time, the cut ends of the needle threads 1a, 1a ... And the looper thread 2a remaining on the sewing material A side. Is pulled out on the needle plate 5 together with the removal, and the needle threads 1a, 1a remaining on the needles 1, 1 ... side are also partially pulled out, but the cut end of the looper thread 2a remaining on the looper 2 side is , First
By holding the sandwiching force between the movable knife 11 and the spring piece 13b of the looper 2, it surely remains below the needle plate 5 without being detached from the operating rod 2b of the looper 2, and confirms the holding state of the looper thread 2a and Since there is no possibility of being forced to reattach to the rod 2b, it becomes possible to quickly shift to the next sewing work, which contributes to the improvement of work efficiency.

Finally, a supplementary explanation will be given in the time chart of FIG. 13 showing the case where the decorative sewing of the upper surface of the sewing material A is carried out. Also in this case, the looper thread 2a and the needle threads 1a, 1a
The operation up to the cutting is performed in exactly the same manner, and the cutting command for the upper decorative thread is added before the subsequent presser foot lifting command.

This cutting command is issued after the needle thread cutting command is stopped.
It is issued after the elapse of the waiting time T ₄ , and the upper decorative thread cutter (not shown) operates in accordance with this command, and the upper decorative thread looper 3 operates to cut the upper decorative thread that is wound as shown in FIG. To be done. Since this cutting is performed on the upper part of the needle plate 5 and there is no risk of interfering with the above-described cutting operation of the needle threads 1a, 1a, ..., It can be performed simultaneously with the needle thread cutting.

After stopping the command for cutting the upper decorative thread, a signal (presser lifting command) for moving the presser foot of the sewing material A upward is issued after waiting a preset waiting time T ₆ and a series of The thread cutting operation of is completed. The waiting time T
₆ is set in consideration of the time required for the upper decorative thread cutter to retreat after the stop of the upper decorative thread command and the time for confirming the end of this operation.

In this embodiment, the air cylinders 21 and 22 are used as the driving means for the first and second movable knife 11 and 12, respectively. Instead of these, other driving means such as solenoids are used. May be. The scope of application of the device of the present invention is
The present invention is not limited to the multi-needle, flat stitch, sewing machine having the tubular bed 4 having the configuration as shown in the embodiment, and other configurations such as a tubular bed having a tubular shaft parallel or inclined with respect to the sewing machine main body B, for example. It is needless to say that the present invention can be applied to a multi-needle flat stitch sewing machine having a tubular bed.

[0072]

As described above in detail, in the present invention, each needle is stopped near the bottom dead center to cut the looper thread, and then each needle is stopped near the top dead center to collectively collect the needle threads. Since the yarn is cut, it is possible to reliably capture these yarns and the subsequent cutting when cutting both yarns, and it is possible to reliably hold only the looper yarn after cutting, and the looper yarn comes out from the looper when the sewing material is removed. There is no fear, and it is not necessary to reattach the looper thread, and a great improvement in work efficiency is achieved. Further, since each thread can be cut by the knife operating on the back side of the needle plate in the plane of the needle plate, the present invention can be applied to a sewing machine having a cylindrical bed with a small diameter. ..

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a process of forming a stitch in a multi-needle flat stitch sewing machine.

FIG. 2 is a plan view of a bed portion of a multi-needle, flat stitch, sewing machine provided with the device of the present invention.

FIG. 3 is a side view taken along line III-III in FIG.

FIG. 4 is an exploded perspective view showing an attachment mode of a knife for cutting a needle thread and a looper thread.

FIG. 5 is a side view showing an operating state of looper thread tension releasing means.

FIG. 6 is an explanatory view of a looper thread cutting operation by the device of the present invention.

FIG. 7 is an explanatory diagram of a looper thread cutting operation by the device of the present invention.

FIG. 8 is an explanatory diagram of a looper thread cutting operation by the device of the present invention.

FIG. 9 is an explanatory diagram of a needle thread cutting operation by the device of the present invention.

FIG. 10 is an explanatory diagram of a needle thread cutting operation by the device of the present invention.

FIG. 11 is an explanatory diagram of a needle thread cutting operation by the device of the present invention.

FIG. 12 is a time chart showing the operation timing of each part of the device of the present invention.

FIG. 13 is a time chart showing the operation timing of each part of the device of the present invention.

[Explanation of symbols]

 1 needle 1a needle thread 2 looper 2a looper thread 4 bed 5 needle plate 5a needle drop hole 7 thread take-up cam device 8 air cylinder 11 first movable knife 12 second movable knife 13 first fixed knife 14 second fixed knife 21 Air cylinder 22 Air cylinder 23 Connecting plate 24 Connecting plate 71 Threading cam

Claims (3)

[Claims] 1. A cylindrical bed which provides a feed in the axial direction,
A needle thread that moves up and down together with a plurality of needles that penetrate the needle plate on the bed to move up and down, and a looper that moves forward and backward according to the up and down movement of each needle on the back side of the needle plate. When,
In a thread cutting method of a sewing machine, which cuts a looper thread entwined with each needle thread by the operation of the looper inside the tubular bed, the needle is stopped near the bottom dead center to cut the looper thread. Then, after that, each of the needles is stopped in the vicinity of the top dead center and the needle threads are collectively cut, whereby a thread cutting method for a sewing machine. 2. A cylindrical bed which provides a feed in the axial direction,
A needle thread that moves up and down together with a plurality of needles that penetrate the needle plate on the bed to move up and down, and a looper that moves forward and backward according to the up and down movement of each needle on the back side of the needle plate. When,
In a thread cutting device of a sewing machine that cuts a looper thread intertwined with each needle thread by the operation of the looper inside the tubular bed, a blade surface of which faces the working end of the looper in the retracted state. 1 fixed knife, a second fixed knife whose blade surface faces the vertical movement path of each needle, and reciprocating motion in response to a stop near the bottom dead center of each needle to operate the looper. In response to the first movable knife that captures and pulls out the looper thread near the end, cuts between the first fixed knife and holds the clamping pressure, and stops near the top dead center of each needle. It reciprocates and enters the loop formed by the plurality of needle threads at the time of forward movement, and by the subsequent return movement, the needle threads are collectively captured and pulled out, and between the second fixed knife and the second fixed knife. A thread cutting device for a sewing machine, comprising a second movable knife for cutting. 3. The thread trimming device for a sewing machine according to claim 2, further comprising means for releasing the tension of the looper thread during the operation of the first movable knife.