DE10127591C1 - Method and device for forming a final knot in a single-thread chainstitch seam - Google Patents

Abstract

The invention relates to a method and a device for forming an end knot of a seam produced using a single-thread chain stitch sewing machine, wherein a thread loop B, which was grasped by the hook after the completion of the seam and which was formed a stitch before the last stitch of the needle, by one by the hook thread loop A formed at the previous stitch and still grasped by the latter is passed and both thread loops are guided around a retaining finger, after which a thread loop C formed when the needle was last inserted is guided through the thread loop B by the gripper at a point in time at which it does has completed the twist created by the detour around the gripper, but has not yet fallen off the gripper (FIG. 4).

Description

The invention relates to a method for forming an end knot a single thread chain stitch seam and a rotating hook and, optionally, a chain stitch sewing an auxiliary looper machine.

For seams created with single-thread chainstitch sewing machines in each case the needle thread loop of the previous stitch opened spreads so that the needle pulls the thread on each subsequent stitch through the loop of the previous stitch. Each subsequent thread loop thus holds the thread loop of the each previous stitch. Since the thread loops but one almost unimpeded slipping through the following company allow the loop, single thread chainstitch seams can be relatively slightly wind up against the stitch pattern direction.

To secure the end of a single thread chainstitch are therefore End knots known, in particular the thread loop fe of the last stitch secured against being pulled open by a knot becomes.

In the method or in the implementation of the method, the sewing machine according to DE 196 41 638 A1 is used to form a knot consisting of several thread loops, with a first thread loop formed two stitches before the last stitch compared to the length of the seam during the actual seam required length of the thread loops is increased by a certain amount, that is, pulled out by a certain amount. Then the lengthened first thread loop is passed through a second thread loop which was formed a stitch before the last stitch, whereby a knot is to be formed during the formation of the last stitch, in which the first thread loop is held in place by the second thread loop. Since after the formation of the second thread loop, the elongated first thread loop has been passed through the second thread loop, after the formation of the knot, the first thread loop is fastened by the knot part which is formed by the second thread loop. As a result, the free end of the first thread loop resulting from the thread cut is still held by the first thread loop even if it has come out of the thread loop, so that the knot formed in this way - according to column 9 , lines 68 ff of DE-A1 - does not can be resolved.

This procedure may offer sufficient security the knot must be reached, however, this requires the two stitches the last stitch formed by an additional loop Thread puller relatively extended on the one hand and by the second Thread loop are pulled through, and on the other hand, the so far drawn thread loop both during the formation of the second and third thread loop kept under control be what relative, especially with regard to their length is difficult and inevitably becomes a correspondingly more complicated one chain stitch sewing machine.

In connection with the formation of single thread chain stitching a method was known from DE-AS 11 68 228, in which one previous loop of threads one by one following thread loop is looped. Here the stichbil end of the thread loop of the previous stitch in Direction of progress of the seam to be formed pulled out and then rotated 180 degrees around a substantially horizontal axis, creating a kind of double loop with intersecting and inside legs lying on a plane arise. Then the front one Part of the double loop thus formed from the intersection of theirs Leg in the direction of the previous puncture so ge swivels that the original front thread loop of the double loop below their other thread loop to lie like this comes that the needle when it sticks through both thread loops this double loop passes, and both thread loops abge be stung. This process can be done on the one hand during the formation of each stitch of a continuous stitch formation as also use on the other hand as a final knot, but here too in view of the fact that the front area of the thread loop for  Formation of the double loop rotated by 180 degrees and the so formed front thread loop below the resulting rear Thread loop must be arranged, the technical effort for a single-thread chain suitable for carrying out this method stitch sewing machine relatively large.

The invention is therefore based on the object Process for forming a final knot for a single thread chain to create a stitched seam, which on the one hand guarantees sufficient Provides security of the final knot, but on the other hand only a minimal technical effort for one to its through suitable single-thread chainstitch sewing machine.

This task is based on a single thread chain stitch machine with a thread-guiding needle, and one with this interacting rotating gripper by the patent in Proceed 1 specified steps.

The techni on which the method according to the invention is based The teaching here assumes that one is sufficient to achieve one two knots formed before the last stitch Knotting stitches are sufficient if the two stitches are in front thread loop A formed by the last stitch by the after Thread cut on the material remaining free end of a stitch in front the thread loop B formed in the last stitch is secured twice, d. H. this thread end twice with the two stitches before the last one Stitch-formed thread loop A is entwined.

To achieve this two intertwining of the ver permanent free thread end uses the teaching of the invention The fact that even with chain stitch sewing machines with rotating The needle thread loop picked up by the hook tip while moving around the gripper by 180 degrees by one The needle is rotated in a substantially parallel axis. These twists hung the thread loop, which after sliding off the hook would revert again, is due to the before the conversion of the Thread loop B around the hook in these retracted retainers  fingers in cooperation with the one before the thread loop fell off fe B from the hook of this through the thread loop B. guided thread loop C prevented.

To achieve the further object on which the invention is based, a single-thread chain suitable for carrying out the method stitch sewing machine to create a structurally low on wall required, this has a retaining finger, which is in the essential in the loop stroke position in the two thread loops A and B is movable.

The restraining finger moves from its rear reversal position in the two thread loops A and B on one movement path, which in the area of the loop stroke position of the needle Trajectory traverses slightly above the eye of the needle to pass through on the one hand in the thread loop A and hanging on the hook on the other hand into the thread loop B just formed by the needle penetrate.

Pull around the thread loop A as far as possible and thus one Excess length of thread loop A despite tightening on the back To be able to avoid holding fingers as far as possible is the tip of the Retaining fingers from their lower trajectory into an im immediate area of throat plate located upper trajectory can be raised and along this upper movement path into the area his rear reverse position can be moved back, in the area of which he can be lowered to the level of its lower trajectory.

It is essential in this context that the restraining finger at Needle located slightly above the loop stroke position halfway through the eye of the needle enters the loops A and B and possible from this thread as close as possible to the underside of the stitch plate grind out.

A suitable one for carrying out the above-described method Single thread chain stitch sewing machine can have a retaining finger sen, which after forming the seam essentially in the Schlin needle stroke position both in the still on the hook  hanging thread loop A of a first stitch, as well as in the from The gripper gripped the second thread and was still pulling it out loop B of a subsequent stitch is movable (claim 2). This allows both threads with a single movement of the restraining finger loops A, B can be grasped by this.

An extension that is only insignificant compared to the formation of the seam thread loop A can be reached if the back tefinger along a lower trajectory in the two threads grind A, B retractable and from this into an immediate Position of the throat plate within an upper position Movement path can be raised (claim 3).

The length of the loop A can thereby be further increased minimize that the throat plate has a recess on its underside has, and the retaining finger is movable in this (claim 4).

The movement of the restraining finger from its rearward reversal position to the front reverse position and also this subsequent movement from its lower trajectory to its upper trajectory with just one movement to carry out its drive means is the restraining finger of one rocker arm movable relative to a carrier, wherein the carrier with the trained as an oscillating shaft driving means is firmly connected, and the retaining finger in the area of front reversal of its lower trajectory through a relative movement of the. derived from the movement of the carrier The rocker arm can be raised to the carrier in the upper movement path is (claim 5).

In terms of construction, the derivation of the relative movement can be simply realize the rocker arm to the carrier when this a double lever is mounted on the carrier, one end of which is on itself be in the area of the front reverse position of its movement path sensitive retention finger rests against a stop and its other end via an intermediate bearing mounted on the oscillating shaft member with the rocker arm in drive connection (claim 6).  

To secure the relative position between the rocker arm and the Carrier along the movements of the restraining finger its lower or upper trajectory is a rotation on the carrier spring attached, one leg of the rocker arm and whose other leg is supported on the carrier (claim 7).

Provided that the restraining finger moves from its lower to its upper Relative movement between the oscillation leading the trajectory lever and the carrier against the bias of the torsion spring follows, this can move through the movement of the restraining finger from its upper to its lower trajectory again to relax partially so that it is necessary for the implementation of this movement No special drive is required and it is used for feedback of the retaining finger from its holding the thread loops A, B. Position towards his on the lower trajectory terem reverse position also only a single movement of the Vibration wave requires (see claim 8).

Further advantages and details of both the invention Method and the single-thread formed according to the invention Chain stitch sewing machines result from the following Be description of an exemplary embodiment shown in the drawings game of the invention.

It shows:

Figure 1 shows the situation of the thread loops A and B at the beginning of the formation of the final knot.

Figure 2 shows the situation of the thread loops A and B with the penetrated into this retaining finger in its lower position.

Fig. 3, the raised thread loop A with eingedrunge in this nem retaining fingers in its upper position and partially coated thread loop B;

FIG. 4 shows the situation of the thread loops A and B just before detecting a further loop of thread C by the gripper;

Fig. 5 shows the situation of the thread loops A and B after the thread loop B has dropped from the gripper and partially pulled-out thread loop C and partially retracted retaining finger;

Fig. 6, the situation of virtually tightened thread loops A and B, as well as the more solid thread loop C;

Fig. 7, the end knotting after the thread cutting;

Fig. 8 is a front view of a schematically illustrated stitch sewing machine, partly in section;

Fig. 9 is an end view of the device for forming the Endverkno device with be in the region of its rear reverse position retaining fingers;

Fig. 10 is an end view of the device for forming the Endver knot with restraining fingers located in the region of its front reverse position;

FIG. 11 is an enlarged sectional view according to FIG. 1 of the area of the device for forming the end knot;

Fig. 12 is a plan view of the area of the sewing machine shown in Fig. 11.

The following is the procedure and then the procedure described its implementation created chain stitch sewing machine ben.

In Fig. 1, the situation of the thread loops is shown at the beginning of the formation of the end knotting.

At this point, the one formed in the previous stitch hangs Thread loop A still on the hook. It runs over from the sewing material  the auxiliary gripper in its forward reverse position to the gripper. The needle is in the loop stroke position and then leaves it upwards. The next thread loop B is formed and the tip of the gripper has penetrated into it. The Retention finger has shifted from its rear reverse position to The needle moves with its tip neither in the thread loop A has still penetrated the thread loop B. The top of the back haltefingers is just before thread loop B.

When the gripper continues to rotate, the thread loop A hanging on the gripper moves on its back to its tip and is about to fall off the back of the gripper. The thread loop B is pulled out further from the tip of the hook. The restraining finger has moved along its lower movement path both into the further extended thread loop B and into the thread loop A ( FIG. 2).

After the thread loop A has fallen off the gripper and the gripper has pulled out the thread loop B further, the thread loop A is pulled up in the usual way by the thread lever. At the same time, the restraining finger is raised from its lower trajectory to the level of its upper trajectory and is located directly below the needle plate. As a result, this is tightened on the restraining finger just enough that the restraining finger can later be moved out of the thread loop A while avoiding an excess length of the thread loop A. During the pulling up of the thread loop A, the gripper has rotated further and the thread loop B has expanded further. The thread loop B is not yet twisted ( Fig. 3).

When the hook continues to rotate, the position and length of the thread loop A have not changed, so that their length is only greater by the amount resulting from their detour around the retaining finger compared to their length during the normal sewing process. The restraining finger is still in the position shown in FIG. 3. In the meantime, the needle has moved back to its looping stroke position after reaching its bottom dead center position and continues its upward movement. While the thread loop B is still tensioned on the gripper and runs from there via the auxiliary gripper to the retaining finger, its tip detects the next following thread loop C and begins to guide it around the gripper ( FIG. 4).

Due to the redirection of thread loop B in the meantime the rotating gripper, this was (as is the case with rotating Lockstitch circulating grippers as well as rotating chain stitch grit distant is usual) by 180 degrees around a to the needle essentially pa parallel axis rotated. The tip of the gripper guides the Thread loop C before the thread loop B thus rotated falls off from the hook through thread loop B, which is then from The gripper can fall off and be pulled up.

Since ent ent by the thread loop B around the hook The twist is due to the fact that the thread loop C before the loop B comes off the hook the thread loop B is passed through, do not form back again can, the thread loop B has the form of a kind of double loop.

While the thread loop B is being pulled up, the thread loop C is further guided around the gripper and is stretched over its back. This situation is shown in FIG. 5, which shows the course of the thread loops before the thread loop B begins to close and the partially pulled thread loop C, which is still on the hook. The restraining finger now moves back along its upper trajectory to its rear reversal position and is lowered to the level of its lower movement path to reach its starting position to form the next final knot. At the same time, the auxiliary gripper moves back to its rear reverse position ( Fig. 5).

In Fig. 6 the course of the thread loops A, B and C B is shown just before the end of the Zuziehens the thread loop, the run nor the looper thread loop C is tensioned.

It can also be seen from FIG. 6 that the thread loop A is almost closed and its two legs run to the material to be sewn or to the button to be sewn on. The thread loop B is also almost closed, both its leg B1 to the thread loop A and its leg B2 extending to the thread loop C leg B2 is guided through the thread loop A. From the thread loop C still guided over the looper, one leg C1 leads to the leg B2 of the thread loop B, while the leg C2 leads to the needle in a manner apparent from FIG. 6 via the material to be sewn.

The course of the thread loops A, B and C shown in Fig. 6 corresponds essentially to the thread course when cutting the thread loop C. The thread is cut in a manner known per se in the region of the leg C1 of the thread loop C, as a result of which the knot thus formed remains Thread end is relatively short and the free thread end leading to the thread supply, on the other hand, becomes comparatively long ( FIG. 7).

The single-thread chainstitch sewing machine shown schematically in FIG. 8 has a thread guiding needle 2 , which cooperates in a known manner with a rotating gripper 1 , both of which are driven in a known manner from a main shaft, not specified. If the single-thread chainstitch sewing machine shown in connection with an exemplary embodiment is one for sewing buttons, in which the sewing material is not usually transported, it is also equipped with an auxiliary hook 3 , which in the usual way for holding the thread loops interacts with the gripper 1 . The auxiliary gripper 3 is arranged in a known manner on an oscillating shaft 4 , which is also displaceably driven in the axial direction. The auxiliary hook 3 , which is necessary for button sewing machines for the sake of stitch formation, is stitched for the formation of the end knot of the single-thread chains without any functional meaning and therefore only mentioned for the sake of completeness.

The device for forming the end knot has a retaining finger 5 , shown in more detail in FIGS . 1 to 7, which is driven by an oscillating shaft 6 . For this purpose, a crank 7 is fastened on the oscillating shaft 6 , which is connected via a joint connection, not shown, to a double-acting pneumatic cylinder 8 which can be controlled by the main control of the machine.

The movements of the oscillating shaft 6 serve both to hold the back retaining finger 5 along a lower trajectory from a rearward reverse position to its loop-detecting front reverse position and along an upper trajectory thereof in its rearward reverse position. Furthermore, both the movement of the oscillating shaft 6 in the region of the lifting movement of the restraining fin 5 taking place before its reversing position is derived from its lower movement path into its upper movement path and also its lowering movement taking place in the region of its rear reversing position from the upper movement path to the lower movement path ,

At the - with respect to FIG. 8 - left end of the oscillating shaft 6 , a carrier 9 is arranged, which is firmly connected to the oscillating shaft 6 . In the carrier 9 , a pin 11 is mounted, which serves to receive a rocker arm 12 to which the retaining finger 5 is attached. On the support 9 , a pin 13 is also attached, on which a double lever 14 is pivotally mounted, the upper end 15 of which interacts with a stop 16 formed by a screw fixed to the housing together. The lower end 17 of the double lever 14 carries a zap fen-like driver 18 which projects into a slot 19 of a lever 21 which is loosely mounted on the oscillating shaft 6 . On the lever 21 , a second slot 22 is provided, in which a pin 23 engages, which is on the other hand received by the rocker arm 12 and laterally protrudes from it. At the pin 23 is a leg 24 of a rotary spring 25 , which is taken up by a screw 26 fixed in the carrier 9 . The other leg 27 of the torsion spring 25 rests on a pin 28 fastened in the carrier 9 . The torsion spring 25 has a certain bias. To be able to adjust the position of the retaining finger 5 which projects into the slot 22 of the lever 21 pin 23 is of the retaining finger 5 receiving the oscillating lever 12 befindlichem at in the region of its rear reversing position retaining fingers 5 at an adjustable stop 29 at which a in the carrier 9 screw is formed.

To transfer the retaining finger 5 from its Darge in FIG. 9 rear reversed position into its position detecting the loops A and B, the retaining finger 5 is moved along its lower path of movement. For this purpose, the carrier 9 is swung out by the oscillating shaft 6 . The arranged on the pin 13 Dop pelhebel 14 and the verbun via this driver 18 with this lever 21 take part in the pivoting movement without performing a relative movement to each other. The retention finger 5 can enter the thread loops A and B.

As soon as the upper end 15 of the double lever 14 has reached the stop 16 and bears against it, the double lever 14 is pivoted about the pin 13 fastened to the support 9 , its lower end 17 - based on FIG. 9 - clockwise around the pin 13 is pivoted. As a result, the lever 21 is pivoted about the oscillating shaft 6 in the counterclockwise direction due to the driver 18 projecting into its slot 19 .

During the counterclockwise Schwenkbe movement of the lever 21 , the rocker arm 12 is carried by its protruding into the slot 22 of the lever 21 pin 23 and - based on FIGS. 9 and 10 - pivoted clockwise around the pin 11 . Here, the torsion spring 25 is further stretched over its leg 24 abutting the pin 23 and at the same time the retaining finger 5 is raised from its lower movement path to its upper movement path, so that both the carrier 9 and the retaining finger 5 have reached their end position of the movement detecting the thread loops , As can be seen from FIGS. 9 and 10, the retaining finger 5 can be raised so far that it projects into a recess 32 provided on the underside of the needle plate 31 , whereby the thread loop A is only slightly longer than in the normal stitch formation becomes. The restraint finger 5 is held after the thread loop A is tightened on it, also by this in its upper trajectory.

After the recording of the last loop of thread C by the hook tip, the return movement of the retaining finger 5 can in its position toward direct reversal is along its upper movement path passes.

For this purpose, the pneumatic cylinder 8 is controlled via the main control of the machine and the crank 7 is moved back to its starting position. As a result, the restraining finger 5 initially moves along its upper trajectory in the direction of its rear trajectory. Since the restraining finger 5 is initially still within the two thread loops A and B, it is held in its upper position by these. As soon as it has moved out of the two thread loops A and B, it is pivoted back into its lower movement path due to the now relaxing torsion spring 25 about the pin 11 .

Claims (8)

1. A method for forming an end knot of a single-thread chain stitched by means of a thread-guiding needle and a rotating hook interacting with it and optionally a chain stitch sewing machine having an auxiliary hook characterized by the following steps:

• a) performing a thread loop gripped by the tip of the gripper B through the thread loop A still grasped by the gripper in the previous stitch and leading from this to the gripper;
• b) Introducing a substantially horizontally directed tefinger in the thread loops still gripped by the gripper A and B in such a way that both thread loops A and B are guided around the retaining finger;
• c) moving the retaining finger from its lower path of movement into a raised position, preferably located in the immediate area of the underside of the throat plate, and pulling in the thread loop A;
• d) Detecting the thread loop C formed by the hook tip when the needle is next inserted and passing the thread loop C through the thread loop B at a point in time at which it has completed the twist caused by its detour around the hook, but not yet by the hook has dropped;
• e) moving the retaining finger back out of the thread loops A and B and pulling the thread loop B;
• f) severing the strand of thread loop C leading from the interlacing point of thread loops A and B to the gripper in the area of the interlacing point of thread loops A and B.

2. Single-thread chainstitch sewing machine with a thread-guiding needle, a cooperating with this rotating gripper and optionally an auxiliary gripper, and a device for forming an end knot of the seam to be produced, characterized in that it has a retaining finger ( 5 ) after the seam has been formed when the needle ( 2 ) is essentially in the looping stroke position, both in the thread loop A of a first stitch still hanging on the hook ( 1 ) and also in the second thread loop B of a subsequent one which is gripped by the hook ( 1 ) and is still to be pulled out by the latter Stitch is movable. 3. single-thread chainstitch sewing machine according to claim 2, characterized in that the retaining finger ( 5 ) along a lower movement path in the two thread loops A, B retractable and from this in a in the immediate area of the needle plate ( 31 ) position within half of an upper Movement path can be raised. 4. Single-thread chain stitch sewing machine according to claim 3, characterized in that the needle plate ( 31 ) has a recess ( 32 ) on its underside, and the retaining finger ( 5 ) is movable therein. 5. Single-thread chain stitch sewing machine according to claim 2 and 3, characterized in that the retaining finger ( 5 ) is received by a rocker arm ( 12 ) movable relative to the carrier ( 9 ), the carrier ( 9 ) being fixed with a drive means (oscillating shaft 6 ) is connected, and the back retaining finger ( 5 ) in the region of the front reverse position of its unte ren movement path by a movement of the carrier ( 9 ) derived relative movement of the rocker arm ( 12 ) to the carrier ( 9 ) in the upper movement path can be raised. 6. Single-thread chain stitch sewing machine according to claim 5, characterized in that to achieve the relative movement between the rocker arm ( 12 ) and the carrier ( 9 ) on this a double lever ( 14 ) is mounted, one end ( 15 ) of which is in the region the front reverse position of its trajectory located retaining finger ( 5 ) abuts a stop ( 16 ) and the other end ( 17 ) via an intermediate member (lever 21 ) mounted on the oscillating shaft ( 6 ) is in drive connection with the oscillating lever ( 12 ). 7. Single-thread chain stitch sewing machine according to claim 5 and 6, characterized in that the relative position between the carrier ( 9 ) and the rocking lever ( 12 ) by a carrier ( 9 ) received torsion spring ( 25 ) is determined, one leg ( 24 ) is supported on the rocker arm ( 12 ) and its other leg ( 27 ) on the carrier ( 9 ). 8. Single-thread chainstitch sewing machine according to claim 7, characterized in that the relative movement between the rocker arm ( 12 ) and the carrier ( 9 ) takes place against the bias of the torsion spring ( 25 ), and the retaining finger ( 5 ) is in the region of the front reverse position ner upper trajectory is held in the upper trajectory by the thread loop A recorded by him.