DE102015005298A1 - Multi-needle chain stitch sewing machine - Google Patents

Abstract

With the invention, a Mehrnadelkettenstichnähmaschine to be able to produce in a single operation parallel to each other running chain stitches that have a small distance from each other and in which the puncture sites of the seams with respect to their longitudinal direction have no offset from each other. For this purpose, a Mehrnadelkettenstichnähmaschine is provided with a plurality for receiving a needle thread (5) leading provided needles (2), wherein the plurality of needles along a straight line each spaced from each other and are movable synchronously with each other, and the line at least substantially is aligned orthogonal to the intended feed direction of a fabric transport, further comprising a yarn guide (4) for the plurality of upper threads to guide each upper thread (5) from its thread supply (6) to its associated needle, with several each for guiding a lower thread (25 ), wherein the grippers (3) are arranged at a distance from each other and are movable synchronously with each other, by the movements of the gripper (3) and the needles (2) each have an upper and a lower thread (5; 25) are entwined with each other, thereby simultaneously several mutually parallel seams in the material to be produced with in the feed direction without offset from each other arranged in the fabric puncture sites of the needles, and a motor having at least one drive means, with the predetermined and coordinated with each other, the movements of the needles and the gripper can be generated. According to the invention, such a chain stitch sewing machine is provided with a thread tightening means (10) arranged in the area of the thread guide and provided in addition to a thread feeder (11) for at least one of the upper threads (5), with which at least one of the upper threads in the area between the thread tightening means (10). and the at least one upper thread (5) associated needle (2) is providable with an additional thread tension.

Description

The invention relates to a Mehrnadelkettenstichnähmaschine with a plurality for receiving each of a needle thread leading provided needles, wherein the plurality of needles along a straight line spaced from each other and are movable synchronously with each other, and the line is aligned at least substantially orthogonal to the intended feed direction of a Nähguttransports yarn guide for the plurality of upper yarns for guiding each upper yarn from its yarn supply to the needle associated therewith, with a plurality of driven grippers each for guiding a lower yarn, the grippers being spaced apart and movable synchronously with each other by the movements The gripper and the needles in each case an upper and a lower thread are entwined with each other, thereby at the same time several mutually parallel seams in the fabric, with in the feed direction of the fabric without offset each other in the fabric ang eordnete puncture sites of the needles to produce and at least one motor having drive means, with the puncturing movements of the needles and the gripper are generated in a predetermined manner and coordinated with each other.

Chainstitch seams are frequently used in the industrial production of sewing articles, among other things for seams of trousers, in particular jeans. Chainstitch seams, in contrast to lockstitch seams, have a higher elasticity, which is why chainstitch seams are often preferred for such applications. In jeans and other denim apparel, but not just denim, parallel and spaced seams are provided, such as double or triple seams.

For this purpose, two different types of machines have become known. One of the two machine types is called a crossline, the other machine type an inline chain stitch machine. The two types of machine differ mainly in the arrangement of the plurality of needles to each other and in relation to the intended feed direction of the material transport. In cross-line machines, the multiple needles are arranged along a line that encloses, with the fabric transport direction, an angle other than 90 °, usually an acute angle; for example 45 °. Due to the offset of the needles relative to one another in relation to the intended material transport direction, this type of machine is particularly suitable for applications in which the needles can also have a small distance from one another with respect to the material transport direction. In this type of machine, due to the principle-related offset of the stitch pattern tools in the seam formation direction, the risk is low that threads are detected by adjacent stitch pattern tools, resulting in suture deformities.

In contrast, in the case of the in-line chain stitch sewing machines already mentioned, the needles are arranged in a line which runs perpendicular to the intended fabric transport direction. An offset of the needles and the other stitch pattern tools in fabric transport direction is not given here. In particular, the upper thread loops can come here with the or each adjacent grippers in conflict and in particular be covered by these. This results in errors in the stitch formation, which lead at least to optical errors, but usually to seams that do not fulfill their function. For this reason, the distance between adjacent needles of inline chain stitch sewing machines is limited. For the production of mutually parallel seams in one operation, which have a particularly small distance from each other, so far mainly crossline chain stitch sewing machines are used. However, these have the inherent disadvantage that the stitch points of the individual needles in the fabric and thus the seams are offset in their longitudinal direction to each other. This is often undesirable.

The invention is therefore based on the object to provide a sewing machine which is able to produce in a single operation parallel to each other running chain stitches which have a small distance from each other and in which the puncture sites of the seams with respect to their longitudinal direction have no offset from one another.

This object is achieved by a Mehrnadelkettenstichnähmaschine with the features of claim 1. In this case, a sewing machine of the type mentioned in particular should have a thread tightening means arranged in the region of the thread guide for at least one of the upper threads with which at least one of the upper threads in the area between the thread tightening means and the needle associated with the at least one upper thread can be provided with an additional thread tension. An "additional thread tension" here can be understood as meaning a thread tension portion which, due to the action of the thread tightening means, at least temporarily results on the thread or threads and which adds up to a thread tension possibly present even without such thread tightening means.

In previous Mehrnadelkettenstichnähmaschinen the thread guide was usually for each thread with a thread brake and a Fadenanzugshebel (usually also as Yarn called) provided that keep the upper thread under tension, provide the respective needle sufficient thread supply available and withdraw the thread of the thread loop with increasing needle movement after passing through the lower trough to a limited extent between the needle and Fadenanzugshebel. According to the invention, a separate Fadenanzugsmittel is now additionally provided, with which in addition to the thread take-up and preferably at a different location than that of the take-up, in the course of the upper thread, the respective upper thread passive or active is attracted to a certain time. With the suit of at least one upper thread, preferably all upper threads, at least temporarily an additional clamping force can be applied to the respective upper thread.

With these inventive measures, even with a significant reduction in the needle spacing of multi-needle inline chain stitch sewing machines, functionally reliable and at the same time a plurality of closely arranged next to each other chain stitch seams are formed. This is true even for the so-called "Ketteln" in which, for example, at the end of a seam formation without stitched chain stitches are formed. Because of the lack of resistance for the upper threads through the sewing material here is the seaming of closely spaced chain stitches particularly critical and error-prone. As it has been shown, the measures according to the invention, even under these conditions, lead to secure seams without seam forming tools of threads arranged next to one another gripping threads from other than their own seams.

In connection with the present inventions, therefore, significantly smaller needle spacings of adjacent needles of inline multi-needle chain stitch sewing machines can be provided than hitherto. These needle spacings may be selected from a range of 4.4 mm to 2.6 mm, preferably from 4.2 mm to 2.8 mm, and more preferably from a range of 3.8 mm to 3.0 mm.

In an advantageous embodiment of the invention, the at least one thread tightening means may preferably be arranged between the thread brake and the thread take-up lever (thread take-up). At this point, the intended Fadenanzug can perform particularly effective and reliable.

A particularly advantageous embodiment of the invention can provide that only one common thread tightening means is provided for the upper threads of a plurality of needles, preferably for all needles. The this only one Fadenanzugsmittel associated with a plurality of upper thread should be located in an area of action of Fadenanzugsmittel or out, so that the Fadenanzugsmittel can act on the upper threads for a thread suit. Preferably, the plurality of upper threads are passed through the only one Fadenanzugsmittel. With this embodiment of the invention, the thread suit can be realized in a particularly economical manner.

In a further preferred embodiment of the invention, the thread tightening means may be passively movable to exert a force on the at least one upper thread. The design as a passively moving element complex drives for the Fadenanzugsmittel can be avoided. In this advantageous embodiment of the invention, the existing in the upper threads thread tension can be used to make different thread suits in different Stichbildephasen. In addition, this can be done with little effort an automatically performed reset the Fadenanzugsmittels.

Furthermore, it is preferred that the Fadenanzugsmittel is designed as a mechanical spring element, or as a pneumatically acting element or as a cam-controlled element which is movably coupled to a drive device of the sewing machine.

It has also been found to be particularly advantageous that during a Stichbildezyklus, the Fadenanzugsmittel a - with respect to the height of the force exerted on at least one upper thread - variable force provides. This makes it possible, in particular, to exert a force adapted to the upper threads for the respective stitch formation phase and to generate particularly suitable force, in order to generate thread tensiones which are as suitable as possible in the upper threads and which can serve for controlled needle thread loop formation of each needle and / or for controlled entanglement between a respective upper thread and lower thread ,

Thus, it has proven to be advantageous if the thread tightening agent during a stitch forming phase, ie from the top dead center of the needles to the top dead center by the needles, at least two, preferably at least three, at least local maximum values exerted by the Fadenanzugsmittel on the at least one upper thread Strength, goes through. These multiple local maximums can be different sizes or the same size. Likewise, it can advantageously be provided that the thread tightening means repeatedly reaches at least local minimum values of the force exerted by the thread tightening means on the at least one upper thread during a stitch forming phase. These minimum values may also have different values or be the same size. This is it is possible, at least for certain points in time or stages of stitch formation or seam formation to adapt the force with which the thread tightening agent acts on at least one, preferably on all upper threads. It is thereby possible in particular to then apply an increased force to one or more upper threads in comparison to other times when the needles are at least approximately in one of the two dead centers of their movement, ie in the upper or in the lower dead center. At bottom dead center, the needles begin to form their respective upper thread loop by their subsequent upward movement and release. In order to prevent the formation of too large loops, which in particular have too great an extent in the direction of adjacent grippers, an increased thread tightening force on the upper threads at these times can have a favorable effect.

At the top dead center of the needles, a new stitching operation begins, with the loops formed in the immediately preceding stitching operation still resting on the grippers, and the grippers beginning their backward motion, during which the previously formed needle thread loops are released by the grippers due to the backward movement. In order for these upper thread loops to be controlled and released as loops that are not too large, a thread tightening may have a favorable effect approximately at the beginning of the gripper backward movement. In particular, together with the subsequent downward movement of the needle and the subsequent Nähguttransport, which also contribute to the streamlining of the loops located on the loops, so the Oberfadenschlingen can be held taut to the intended jump of the grippers and thus small enough. Since the loops are thus in the backward movement of the gripper largely tight against their grippers, the loops are released to the predetermined phases and at least largely with a predetermined geometric shape.

In a further preferred embodiment of the invention, the force exerted by the thread tightening means on one or more upper threads can then have at least local minimum values when the needles are between their upper and lower dead centers. The minimum values of the thread tightening means can be provided in particular when the needles penetrate into the sewing material and / or leave the sewing material again. During the downward movement of the respective needle can be provided during the penetration of the needle into the fabric by opening a yarn brake for the respective upper thread, a large supply of thread, which should not be reduced by the Fadenanzugsmittel as possible. During the upward movement of the respective needle with the upper thread looping occurs, which is not prevented by the thread tightening means due to excessive thread tensions, but should be controlled by a low action of Fadenanzugsmittel to avoid too large Oberfadenschlingen.

In order to further increase the reliability of the chain stitch formation of a multi-needle chain stitching machine according to claim 1, it can further be provided that the loop stroke is reduced in comparison to previously known loop stroke values. It has proven to be advantageous if the loop stroke has a value from a range of 4 mm to 2.5 mm and preferably from a range of 3.5 mm to 2.7 mm. Under loop stroke here the distance between a bottom dead center of the respective needle and the point along the longitudinal axis of the needle can be understood, on which the gripper intersects the needle longitudinal axis during its movement. The shortening of the loop stroke leads to a reduction of the needle thread loop formed by the needle and thus to a reduction in the risk that adjacent grippers capture the needle thread loop of a needle.

In the same way, a reduced compared to previous movement lengths length of a spreader evasion movement support the measures according to claim 1, in order to achieve a secure stitch formation despite a small needle spacing. It has proven to be advantageous in this case if the spreader deflection movement has a length from a range of preferably 4.5 mm to 4.7 mm.

Each of the grippers may be arranged on a rotary shaft, with which the respective gripper performs a driven alternating pivoting movement. The eccentricity generating the alternating pivoting movement can preferably be reduced in embodiments according to the invention in comparison to otherwise usual eccentricities for driving the pivoting movement of the grippers. In the previously customary smallest needle spacing of 4.8 mm, the eccentricity is approximately 4.9 mm. For example, values from a range of 4.0 mm to 4.6 mm, preferably 4.4 mm, may be provided. As a result, shorter pivoting paths of the gripper can be achieved. As a result, the loop taken up by the gripper is not overstretched and thus an intake of the upper thread is improved.

Further preferred embodiments of the invention will become apparent from the claims, the description and the drawings.

The invention will be explained in more detail with reference to embodiments shown purely schematically in the figures, in which:

1 a multi-needle chain stitch sewing machine according to the invention in a front view, which has an inline needle assembly and is provided with a Fadenanzugsmittel;

2 a Mehrnadelkettenstichnähmschine according to the invention according to the illustration of 1 in another stitching phase;

3 a Mehrnadelkettenstichnähmschine according to the invention according to the illustration of 1 in another stitch formation phase;

4 a Mehrnadelkettenstichnähmschine according to the invention according to the illustration of 1 in yet another stitching phase;

5 A perspective cutout view of the stitching tools of the sewing machine 1 in which the needles are approximately at their bottom dead center;

6 The stitch pattern tools off 5 Starting from 5 are in an upward motion;

7 The stitch pattern tools off 5 Starting from 5 are in an upward motion;

8th The stitch pattern tools according to 5 that are approximately at a top dead center;

9 The stitch pattern tools according to 8th Starting from 8th are in a downward motion;

10 The stitch pattern tools according to 8th Starting from 9 in a further phase of downward movement;

11 An embodiment of a designed as a mechanical spring Fadenanzugsmittel;

12 a diagram in which in a graph, a position of a needle tip over time and in a second graph, a force exerted by the thread tightening agent on at least one upper thread tension force are removed;

13 a perspective view of a driven by a machine main shaft eccentric drive of the gripper.

In 1 is a multi-needle chain stitch machine according to the invention 1 shown, a partially open illustrated housing with an upper part 1a and a lower part 1b having. The housing 1 has in the front view in about a tilted by 90 ° U-shape. In the shell 1a of the housing 1 In particular, there is a drive unit to several synchronously movable needles 2 drive. The needles 2 are arranged in a common needle holder, which in turn is attached to a needle bar. The needle bar is in the upper part with the drive unit 1a the housing operatively connected, so that a drive movement leads to an oscillating rectilinear up and down movement of the needle bar. In other embodiments, each needle could 2 also be attached to its own and each associated needle bar.

In the lower part 1b of the housing 1 a further drive unit is provided, which is also used for the synchronous drive of grippers 3 is provided. Both the grippers 3 as well as the needles 2 belong to stitching tools of the multi-needle chain stitch machine. The two drive units for the needles 2 and the grippers 3 As is known per se, they can have a common motor which drives an arm shaft, from which in turn drive movements are provided and transmitted for each of the two drive units. The basic structure of the two drive units can be constructed according to previously known Mehrnadelkettenstichnähmaschinen. In other embodiments, the needles and the grippers could also be driven by a plurality of separate motors.

In the area of the front of the top 1a is a thread guide 4 intended for upper threads, with which for each needle 2 an upper thread 5 from a thread stock 6 of the respective upper thread 5 to the corresponding needle 2 is guided. The thread guide 4 points, in the feed direction of the upper threads 5 seen, for every upper thread 5 one adjustable and only this upper thread associated yarn brake 7 on, through which the respective upper thread 2 is guided. The upper threads 5 then together through a guide 8th guided. From here, the upper threads arrive 5 together to a thread tightening agent 10 and are through the thread tightening agent 10 passed. In the further course are the upper threads 5 again together by only one thread take-up 11 guided. Subsequently, each upper thread passes 5 to his needle 2 and is done there through the respective bottleneck. Every upper thread 5 performs together with the needle 2 their oscillating movement and in each case forms an upper thread loop required for the chain stitch seam formation in each movement cycle.

In the two representations of 11 is a possible embodiment of a thread tightening agent 10 shown. Here is the thread tightening agent 10 designed as Fadenanzugsfedereinrichtung. This has a carrier 14 on, with that Thread take-up means 10 at the top 1a the housing of the sewing machine can be fastened and the leadership of the thread and a coil spring 15 wearing. The coil spring is 15 on a shaft of the carrier 14 deferred and arranged on this. A front end 15a the coil spring 15 is fixed in place. A housing-side end of the coil spring is as a bracket 15b educated.

The in the lower part 1b of the housing arranged a plurality of grippers 3 are together on a gripper carrier 16 arranged, in turn, by the drive unit in the lower part 1b the housing is driven. This drive movement leads to a common and synchronously executed alternating tilting or pivoting movement of all grippers 3 , The same number as the needles 2 existing gripper 3 can move between two end positions along a predetermined curved path back and forth. The curved or curved path of the grapple 3 may be, for example, a circular arc or an elliptical arc. As in 13 shown are the grippers 3 by means of an eccentric drive 17 driven, which in turn receives its rotational drive movement of the arm shaft in the case of the embodiment. The eccentric drive 17 comprises a shaft rotatably driven by the arm shaft not shown in detail 18 on which an eccentric 19 is arranged. The eccentric 19 acts in the manner of a roller or cam drive and causes the alternating tilting movement of the gripper carrier 16 , About the size of the eccentricity E, the size of the pivot angle of the gripper 3 determined during their alternating pivoting movement. Compared to the size of previous eccentric drives for grippers a lower eccentricity is provided in the embodiment, namely 4.4 mm.

The several identically designed grippers 3 each have approximately for themselves an approximately 90 ° tilted U-shape. With the lower leg 3a The tilted U-shape is each gripper on a gripper carrier 16 attached. Each of the grapples 3 has an upper leg 3b up, from his back end 22 up to its hook tip 23 with a recess 24 is provided for receiving and carrying out the respective gripper 3 assigned only a lower thread 25 through the upper thigh 3b up to its hook tip 23 is provided. In the area of its free end, each gripper runs 3 to its hook tip 23 roughly conical too. The lower threads coming from a lower thread stock 25 are individually and individually by one of the recesses 27 a bobbin threading aid 28 guided. From here, each bobbin thread reaches the area of the connecting leg 3c the U-shape of the respective gripper 3 and here is in the inlet opening of the trained as a passage recess 24 introduced. The bobbin thread 25 then occurs in the area of a top of the hook tip 23 upward and is led away upward to the bottom of the sewing material, not shown.

In the exemplary embodiment with three needles 2 are a total of three grippers 3 provided, which are aligned parallel to each other. In other embodiments, a different number of grippers 3 be present, with the number of grippers 3 always the number of provided needles 2 should correspond. In particular, a number of grippers may be provided from a range of 2 to 10. As well as neighboring needles 2 also have adjacent grippers 3 preferably the same distance from each other, preferably the same distance as the respective grippers 3 associated needles 2 , In the exemplary embodiment adjacent gripper tips are 3.2 mm apart. Likewise, longitudinal axes of adjacent needles 2 , preferably all spaced apart needles 2 , each provided with a distance of 3.2 mm. The needles 2 are arranged along a straight line extending from each of the longitudinal axes of the needles 2 is cut and to which the longitudinal axes are perpendicular. The line also runs perpendicular to the material transport direction. In the presentation of 1 the line is in the drawing plane of 1 or parallel to this drawing plane. The fabric transport direction, however, is perpendicular to the plane of 1 aligned.

In the area between the two thighs is on the gripper carrier 16 a needle shield 35 attached. This has a plurality of spaced struts 36 which are arranged and aligned so that they provide a guide for the needles 2 represent. Unless needles 2 , For example, due to particularly stiff fabric, show a tendency to bend and deviate from their desired path, so this deviation is due to the struts 36 limited and the needles forced to comply at least approximately their target orientation. This will also ensure that the position of the upper thread loops 37 each in the area of the respective upper thread loop 37 associated with a gripper 3 and thus every upper thread loop 37 from their respective gripper 3 can be detected.

Finally located in the area of the gripper 3 also a carrier 38 for several spreader elements. In the embodiment discussed herein, the spreader elements can be used as spreader pins 39 be educated. With each spreader pin 39 At a certain point in the stitch formation, the respective bobbin thread becomes 25 of the respective Spreizerstifts 39 associated with a lower thread 25 detected to laterally deflect this by a spreader escape movement of predetermined length and direction. The spreader escape movement preferably occurs in a direction transverse to the needle movement.

In the 5 to 10 the processes in stitch formation in the area of stitch pattern tools are shown. For the discussion of the procedures in the stitch and seam formation is also referred to below 1 to 4 Referenced, in particular this on the respective upper thread 5 acting Fadenanzugsfeder trained as Fadenanzugsfeder 10 and explain its function. In 5 are the three needles 2 as well as the corresponding three grippers 3 shown. Every needle 2 leads an upper thread 5 which is guided through the respective Nadelöhr and each of the gripper 3 each leads a bobbin thread 25 passing through the upper thigh 3b each gripper is passed. In the presentation of 5 the synchronously moving needle 2 are in the area of their bottom dead center and begin their reversal of the direction of movement to their top dead center. The three grippers 3 are on their way to their final position with their claw tips in front of the needles 2 and at this time of the stitching phase are arranged in front of the plane formed by the three needles. The grippers 3 are in their rear end position, ie in their direction of movement reversal point, in which they have the greatest distance to the needles. Just before reaching this position is from each gripper 3 each a previously generated thread loop 37 of the upper thread, with the associated bobbin thread 25 was swallowed up, due to the movement away from the needles 2 , from the claws 3 jumped. This process will be described below for the following entanglements between the respective upper thread 5 and the associated respective lower thread 25 discussed in more detail.

Part of this engraving phase is the depiction of 3 , As can be seen here, at the time the needles are in place 2 are in their bottom dead center, including the thread take-up 11 arranged in its bottom dead center. The thread take-up spring 10 has become with her strap 15b from her left in the presentation 40 now in the direction of their upper stop 41 moved, in which it exerts the greatest spring tension on the respective upper thread. The passive thread take-up spring 10 is due to an increasing thread tension in the upper threads 5 has been transferred to this position by the latter.

In 6 All needles have along their respective longitudinal axis a little further up in the direction of their top dead center or their upper position, which co-determined the loop stroke, moved and have already begun, a needle thread loop 37 release. The grippers 3 have here in a pivoting motion, in the representation of 6 to the right, to the needles 2 too moved and the latter approximated. Likewise, the thread take-up is 11 in an upward movement. The thread take-up spring 10 is due to a because of the upward movement of the needles 2 , also in the area of thread take-up spring 10 decreasing tension in the upper threads, relieved. The spring force of the Fadenanzugsfeder 10 therefore causes a pivoting movement of the bracket 15b the Fadenanzugsfeder towards their first stop 40 in which the thread take-up spring 10 has the least spring force.

On the way from her position in 6 to their position in 7 have the grippers 3 already the longitudinal axes of the needles 2 happens. How out 7 shows are the grippers 3 with their respective tip by their respective associated only one noose 37 already passed. Also, each emerging from the hook tip lower thread 25 is thus with a section already by the respective associated with him noose 37 guided. The thread take-up 11 leads one with respect to the needles 2 synchronous movement and is also in an upward movement. The thread take-up spring 10 is further relieved due to the decreasing tension of the upper thread and is still on its way to its first stop 40 in which the thread take-up spring 10 has the least spring force.

In 8th have the grippers 3 on their predetermined curved path, in the embodiment here on a circular arc path, further moved to the gripper tip side end position and are in the representation of 8th in this motion reversal position. The grippers 3 have the noose 37 as far as possible on her upper thighs 3b taken, with the slings 37 each tight, ie with the least possible lateral deflection executed. A section of the upper thigh 3b of the respective gripper is with the gripper tips in this position below the spreader pins 39 arranged. The grippers 3 have by their pivoting movement respectively their bobbin thread 25 on a certain side of the spreader pins 39 arranged, namely the side, in the direction below the Spreizerstifte 39 to move. In the presentation of 8th the lower threads are thus each behind one of the Spreizerstifte 39 guided. The needles 2 are now in the position of their top dead center, where their needle thread loop is the largest.

On the stitching phase of the 8th also includes the representation of the front view of the sewing machine of 1 , How out 1 shows, are at this time the thread take-off 11 as well as the needles 2 in their top dead centers. The needle and thread take-up movements as well as the Nähgutvorschubbewegung lead to a Increasing the thread tension in the upper threads 5 , which is why the Fadenanzugsfeder 10 with her strap 15b through the upper threads 5 maximum load is. The thread take-up spring 10 is therefore with the out of the tensions of the upper threads 5 resulting spring force in its upper, second end position 41 held and lies with her strap 15b with this spring force on the upper threads on. The thread take-up spring 10 thus ensures that the upper thread loops 37 are streamlined and have a small lateral deflection.

9 shows a momentary position of the spreader pins 39 in which the spreader pins 39 already started with their lateral deflection and the respective associated associated a bobbin thread. The carrier 38 the spreader elements is together with it held and moved Spreizerstiften 39 - in relation to the presentation of 9 and their drawing plane - has been moved backwards. The Spreizerstifte here have each immediately before each Spreizerstift 39 arranged lower thread 25 taken with this movement and thereby in the direction of movement of the corresponding Spreizerstifts 39 deflected. The needles 2 have already left their position in their top dead center and are on their way towards their bottom dead center again, but are still above the upper leg 3b the gripper 3 arranged. The needle 2 have just stabbed into the fabric. The grippers 3 Now move in a direction opposite to the previously assumed direction of movement direction to the gripper tips facing away from the second end position of the gripper. The needles 2 happen - due to the deflection of the lower threads 25 and - in relation to the presentation of 9 , respectively assigned to the needle and out of this gripper 3 exiting lower thread 25 and in front of this bobbin thread 25 , The needles 2 Then begin the following upper thread loop 37a to build. The needle thread loop formed just before 37 is still through the respective gripper 3 detected as in 9 and also in 10 is shown.

In the presentation of 10 have the needles 2 moved further towards their bottom dead center and also have the gripper 3 happens. The upper threads 5 leading thread feeder 11 continues to move in sync with the needles 2 and also towards its bottom dead center. Furthermore, the grippers have 3 a further subsection in the direction of their gripper tips facing away from the second end position, which in the representation of 10 located on the left. Every bobbin thread 25 is still by a spreader pins 39 deflected. The lower threads 25 come hereby against each one their associated needle 2 in Appendix. In a subsequent upward movement of the needles 2 jump the lower threads 25 from the needles 2 From or are released from the needles and it then finds an entanglement between each lower thread 25 and a noose 37 from one of the upper threads 5 instead of.

With respect to the stitching phases according to 9 and 10 in which are the needles 2 in their downward movement towards their common bottom dead center, the thread take-up spring pivots 10 from their previously taken upper end position 41 , in which it is loaded with their maximum spring force, to their left-side end position 40 in which it has the least spring force and thus at least almost no tensile force on the upper threads 5 can muster. The still on the respective gripper 3 located and formed in the previous stitch forming process Oberfadenschlingen 37 each become taut on their respective grippers 3 held. By relieving the Fadenanzugsfeder 10 Tensile is applied to the compared to other thread conditions otherwise comparatively low tensioned or even almost loose upper thread.

In 12 is to illustrate a possible for the invention and advantageous principal course of the Fadenanzugsmittel 10 applied force, in the case of the embodiment of a spring force. In other embodiments, the force provided for the thread suit may be provided in other ways than by a spring. This force acting on the at least one, preferably on all upper threads at the same time, is variable during a stitch formation cycle, that is to say from a position of the needle tips in their top dead center until the subsequent top dead center is reached again. As seen from the diagram of 12 In this case, it is preferred that the force exerted by the thread tightening force during the previously mentioned stitch formation cycle occupy a maximum value several times, at least one local maximum value in each case. Likewise, during a stitching cycle, the force of the thread tightening means may take on a minimum value, at least in each case a local minimum value, several times. It has proven to be advantageous in this case if at least local maximum force values acting on the upper threads are set in the upper and lower dead center of the needles. Minimum force values can be present in particular when the needles penetrate into the sewing material and / or when the needle tip leaves the sewing material in the upward movement. Like the path of the needles, the course of the force of the thread tightening means can also correspond to a cosine curve or a cosine function. As in 12 In this case, the respective minimum value may be a non-zero positive value of the force. It is also possible that at least one of the minimum values during a stitch formation phase has the value zero.

As shown on the embodiment discussed herein, can thus by the invention, despite a very small needle spacing of adjacent needles 2 , Which are arranged according to the inline principle of a multi-needle chain stitch sewing machine, a secure seaming of closely spaced seams are made possible. It can be avoided in particular that adjacent, ie belonging to an adjacent seam stitching tools, detect an upper thread and thus prevent seaming.

LIST OF REFERENCE NUMBERS

1

Multi-needle chain stitch machine

1a

top

1b

lower part

2

needle

3

grab

3a

lower thigh

3b

upper leg

3c

connecting leg

4

Thread guide upper threads

5

upper thread

6

yarn supply

7

thread brake

8th

guide eye

10

Thread take-up means

11

thread feeder

14

carrier

15

coil spring

15a

front end

15b

hanger

16

gripper carrier

17

eccentric

18

wave

19

eccentric

22

rear end

23

hook tip

24

recess

25

lower thread

26

Under yarn supply

27

recess

28

Unterfadenseparierungshilfe

35

needle guard

36

strut

37

Upper thread loop

37a

following upper thread loop

38

carrier

39

spreader pin

40

left stop

41

upper stop

e

eccentricity

Claims (15)

Multi-needle chain stitch sewing machine with several for receiving one each an upper thread ( 5 ) leading provided needles ( 2 ), wherein the plurality of needles along a straight line in each case arranged at a distance from each other and are movable synchronously with each other, and the line is aligned at least substantially orthogonal to the intended feed direction of a fabric transport, with a thread guide ( 4 ) for the several upper threads, around each upper thread ( 5 ) from their thread stock ( 6 ) to the associated needle, with several each for guiding a lower thread ( 25 ) leading driven grippers ( 3 ), whereby the grippers ( 3 ) are arranged at a distance from each other and are movable synchronously with each other, by the movements of the gripper ( 3 ) and the needles ( 2 ) one upper thread and one lower thread ( 5 ; 25 ) are entwined with each other, thereby simultaneously a plurality of mutually parallel seams in the fabric to produce with in the feed direction without offset each other in the fabric arranged injection points of the needles, and at least one motor having drive means, with the predetermined and matched to each other in the movements of the Needles and the gripper can be generated, characterized by a arranged in the region of the thread guide and in addition to a thread take-up ( 11 ) provided Fadenanzugsmittel ( 10 ) for at least one of the upper threads ( 5 ), with which at least one of the upper threads in the region between the Fadenanzugsmittel ( 10 ) and the at least one upper thread ( 5 ) associated needle ( 2 ) is providable with an additional thread tension. Multi-needle chain stitch sewing machine according to claim 1, characterized in that the at least one thread tightening means ( 10 ) with respect to a course of upper threads ( 5 ), between at least one yarn brake ( 7 ) of these upper threads ( 5 ) and together with the needles ( 2 ) moving thread feeder ( 11 ) is arranged. Multi-needle chain stitch sewing machine according to at least one of the preceding claims, characterized in that for several, preferably for all, upper threads ( 5 ) a common thread tightening agent ( 10 ) is provided, with the same time on the several upper threads ( 5 ) is acted upon. Multiple needle chain stitch sewing machine according to at least one of the preceding claims, characterized in that the thread take-up means ( 10 ) is a passively moved element acting on at least one of the upper threads. Multi-needle chain stitch sewing machine according to at least one of the preceding claims, characterized by a thread tightening means ( 10 ), which is to rest on at least one, preferably on all, upper threads ( 5 ) is provided. Multi-needle chain stitch sewing machine according to at least one of the preceding claims, characterized in that the thread take-up means ( 10 ) is designed as a mechanical spring element, or as a pneumatically acting element or as a cam-controlled element which is movably coupled to a drive device of the sewing machine. Multi-needle chain stitch sewing machine according to at least one of the preceding claims, characterized in that during a stitch forming cycle the thread tightening means ( 10 ) exerts a variable force on at least one of the upper threads. Multi-needle chain stitch sewing machine according to at least one of the preceding claims, characterized in that the thread take-up means ( 10 ) during a stitch formation cycle in which the needles move from their top dead center to a bottom dead center and back to top dead center, at least two, preferably at least three, at least local maximum values of the yarn tightening agent on the at least one upper thread ( 5 ) exerted force. Multi-needle chain stitch sewing machine according to at least one of the preceding claims, characterized in that the thread take-up means ( 10 ) during a stitching cycle, in which the needles move from their top dead center to their bottom dead center and back to top dead center, at least two, at least local minimum, values of the yarn tightening agent ( 10 ) on the at least one upper thread force exerted. Multi-needle chain stitch sewing machine according to at least one of the preceding claims, characterized in that the thread take-up means ( 10 ) each have an at least local maximum force on at least one of the upper threads ( 5 ) when the needles ( 2 ) go through their top and bottom dead center. Multi-needle chain stitch sewing machine according to at least one of the preceding claims, characterized in that the thread take-up means ( 10 ) on the way of the needles ( 2 Have at least one at least local minimum value both between the top and bottom dead centers and on the way between the bottom and top dead centers. Multi-needle chain stitch sewing machine according to at least one of the preceding claims, characterized in that the needle spacing of adjacent needles ( 2 ) is selected from a range of 4.4 mm to 2.6 mm, preferably from 4.2 mm to 2.8 mm, and more preferably from a range of 3.8 mm to 3.0 mm. Multi-needle chain stitch sewing machine according to at least one of the preceding claims, characterized in that a spreader deflection movement is selected from a range of 4.5 mm to 4.7 mm. Multi-needle chain stitch sewing machine according to at least one of the preceding claims, characterized in that an eccentricity of a roller or cam drive of at least one, preferably all grippers, from a range of 4.8 mm to 4.0 mm, preferably with a value of 4.4 mm is selected. Mehrnadelkettenstichnähmaschine according to at least one of the preceding claims, characterized by a needle spacing of longitudinal axes of adjacent needles, from a range of 3.8 mm to 3.0 mm, preferably from 3.6 mm to 3.1 mm, and particularly preferably with a value of 3.2 mm.

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