EP2360305B1 - Method for operating a sewing machine and sewing machine - Google Patents

Description

The invention relates to a method for operating a sewing machine, in particular a Doppelkettenstichnähmaschine, preferably a Vielnadeldoppelkettenstichnähmaschine having a Nähorganpaar from a, piercing a needle needle and a arranged below a Nähgutauflage, along a movement path movable gripper, with the needle, an upper thread through the resting on the fabric support fabric is performed, which is connected to a bobbin, in particular concatenated. The invention further relates to a sewing machine, in particular a Doppelkettenstichnähmaschine, preferably a Vielnadeldoppelkettelstichnähmaschine, with a Nähorganpaar from a needle piercing a fabric and arranged below a fabric support, along a movement path movable gripper, the needle resting an upper thread by the on the Nähgutauflagen Sewing leads and the upper thread connected to a bobbin thread, in particular, is chained.

Such methods and sewing machines are known in the art.

For example, this describes DE 43 15 802 C2 a VielnadelDoppelkettenstichnähmaschine with a Nähorganpaar from a piercing into a fabric needle and a arranged below a Nähgutauflage, along a circular arc segment-shaped movement path movable gripper. With the needle, an upper thread is passed through the resting on the Nähgutauflage sewing material and connected below the Nähgutauflage with a lower thread, namely concatenated, so that a double chain stitch is formed in the fabric.

In the case of the multi-needle double-chain stitch sewing machine previously known from the document mentioned above, the gripper can basically be moved back and forth between two end positions during the sewing process along an arcuate path of movement, so that the gripper performs an oscillating movement. If necessary, the gripper can then be controlled by means of a crank drive, so that the gripper performs a supplemented movement along the circular arc-segment-shaped trajectory compared to the usual oscillating movement during the sewing process. As a result, the upper thread passes into the region of a gripper knee, in which a cutting blade is arranged, which serves to cut the upper thread.

From the US 5 154 130 Another embodiment of such a multi-needle sewing machine is known in which the upper thread is to be cut at a given time. In this known Vielnadelnähmaschine a usually existing spreader is shown in addition, which cooperates with needle and gripper and has a semi-circular recess in which a cutting edge is arranged so that the upper thread can be selectively cut by means of this cutting edge of the spreader, as soon as this is provided.

This document shows very clearly in the figures 5 a) to 5 m) the usual sequence of formation of a chain stitch, the figures 5 a) to 5 i) the usual sewing process and Figures 5 j) to 5 m) the cutting of the upper thread represent.

The above-described prior art basically shows ways in which the upper thread can be cut at the desired time. This point in time may, for example, be predetermined by an electronic control of the multi-needle sewing machine and may be necessary in particular when changing the sewing area in the large-sized sewing material. The same applies if different material samples are to be executed in a large-sized fabric. Such cutting of the upper thread prevents post-processing of the material at the end of the sewing process, in which manually or mechanically the upper thread, which does not run through the sewing material between adjacent Nähmustern. It has also proved to be a disadvantage in this respect that a subsequent processing of the cutting of the upper thread leads to a large upper thread expense. Furthermore, such manual and / or mechanical post-processing time and labor intensive and do not lead mandatory for a required uniformity of the material samples on the visible surface of the fabric.

In the area of the lower thread, such aesthetic disadvantages generally do not occur, so that lower threads have not yet been cut or not specifically cut.

At this point, the invention begins. The invention is based on the Augabe , a generic method for operating a sewing machine in such a way that the required amount of thread of the lower thread is reduced to form a clean Nähgutmusterbildes on the underside of the fabric. It is another object of the invention to form a generic sewing machine such that an inventive method can be carried out in an advantageous manner while avoiding the disadvantages presented above in an economical manner.

To solve this problem is provided by the inventive method that the lower thread is required, cut by means of a cutting tool, which is at least predominantly not moved in a movement parallel to the Nähgutauflage, in particular along a circular arc segmental movement path corresponding to a movement path of a pivoting movement of the gripper.

By this invention, the possibility is achieved that, for example, after completion of a Nähgutmusters in a fabric not only the upper thread is cut as needed, but that the lower thread is cut with a required length, so that during further transport of the fabric and re-attaching the sewing neither a Upper thread above the fabric still underneath thread is pulled underneath the material, which is then arranged extending on the top or the bottom of the fabric, without being sewn to the fabric in this area, so that, if necessary, a subsequent cutting this bobbin thread is required.

For this purpose, it has proven to be advantageous that a cutting tool is provided, which is guided along a movement path which does not run substantially parallel to the Nähgutauflage.

According to a further feature of the invention, it is provided that the cutting tool is moved via a gripper shaft driving the gripper. As a result, the construction effort of a sewing machine is significantly reduced because of the gripper shaft not only the gripper, but also the cutting tool is driven. A coupling may be provided between the cutting tool and the gripper shaft, so that the cutting tool is coupled with the gripper shaft at the predetermined time and then moved in the direction of the lower thread, so that the cutting operation can be performed.

It is provided according to a further feature of the invention that the cutting tool is moved during the cutting process into the area of the lower thread, in particular to the plant at least one cutting surface on the lower thread and the cutting process by a movement of the material relative to the Nähgutauflage and / or by a complementary Movement of the cutting tool is performed. There are thus two ways to perform the cutting process. On the one hand, there is the possibility that the cutting tool is moved in such a way that it is moved in a first step into the region of the lower thread and then in a second step carries out a complementary movement which is sufficient to bring a previously in contact with the thread Leading cutting surface through the lower thread, whereby this is cut. But it is also possible that after the first step described above, the fabric is moved so that the lower thread is pulled into the cutting surface and cut. In this approach, it has proven to be advantageous that is clamped with the movement of the fabric of the lower thread, so that the cutting of the lower thread is simplified and thus carried out with greater security.

According to a further feature of the invention it is provided that the cutting tool is moved together with the gripper. For this purpose, it is structurally provided that cutting tool and gripper are arranged, for example, together on a gripper shaft connected to the gripper holder.

A further simplification of the method according to the invention and thus an increase in operational reliability is achieved by the cutting tool and the gripper being moved on a circular arc-shaped path of movement to a region in which the cutting tool does not come into contact with the lower thread and the cutting tool during the sewing process and gripper to execute the Cutting along the trajectory with the same direction of movement over the area are moved over, which is run over during the sewing process. This development of the method according to the invention allows a structurally simple embodiment of a sewing machine according to the invention to be described below in that the gripper shaft is moved during the sewing oscillating between two end points along a circular arc section-shaped path, so that reliably prevents contact of the lower thread with the cutting tool during the sewing process becomes. If a cutting operation is intended to be performed, the gripper shaft is driven in such a way that it passes over a supplementary section of the movement path, whereby the cutting tool comes into contact with the lower thread and cuts it either directly or by movement of the material.

In addition to the above embodiments of the method according to the invention may further be provided that the upper thread is cut if necessary by means of a cutting tool that is arranged in the region of the gripper or a spreader. Preferably, the upper thread is cut independently of the lower thread. But it can also be provided that lower thread and upper thread are basically cut in the same process step, with a simultaneous cutting is not required.

The solution of the above-described problem provides for a sewing machine according to the invention a cutting thread as required cutting cutting tool, which is at least predominantly not parallel to Nähgutauflage, in particular along a circular arc segment-shaped movement path corresponding to a movement path of a pivotal movement of the gripper movable.

Preferably, the gripper is arranged in particular interchangeable on a gripper holder, wherein the gripper holder is connected to an oscillatingly driven gripper shaft. In addition, it is provided that the cutting tool, which is preferably also exchangeably connected to the gripper holder, complements the gripper. Such a gripper, for example, is substantially L-shaped and has a gripper tip at the end of a leg and a male element at the end of the second leg. It has proven to be advantageous to arrange the cutting tool downstream of the gripper on the gripper holder, wherein the term "downstream" is based on a movement of the gripper in the direction of the hook tip. In principle, it is also possible to arrange the cutting tool in front of the gripper.

In a simple way, a cutting tool with two blades is formed, which are connected to each other with the inclusion of an acute angle, wherein the angle is preferably adjustable. The two blades can thus be adjusted depending on the thread thickness and the thread material to achieve a safe cutting result. Of course, a blade in a U-shaped configuration is possible.

In the substantially L-shaped gripper is further provided that in the transition between the two legs, a second cutting tool for cutting the upper thread is arranged so that both the upper thread, and the lower thread can be cut by means of the gripper and the first cutting tool ,

Fig. 1

das Nähorganpaar in Seitenansicht in einer ersten Stellung zur Ausbildung eines Kettenstichs,

Fig. 2

das Nähorganpaar gemäß Fig. 1 in einer zweiten Stellung zur Ausführung eines Kettenstichs;

Fig. 3

das Nähorganpaar gemäß den Fig. 1 und 2 in einer dritten Stellung nach Schneiden eines Oberfadens;

Fig. 4

das Nähorganpaar gemäß den Fig. 1 bis 3 in einer vierten Stellung kurz vor einem Schneiden eines Unterfadens;

Fig. 5

das Nähorganpaar gemäß den Fig. 1 bis 4 in einer fünften Stellung während des Schneidvorgangs des Unterfadens und

Fig. 6

eine weitere Stellung des Nähorganpaares gemäß den Fig. 1 bis 5 zur Einstellung einer Restfadenlänge vor dem Schneiden des Unterfadens.

Further features and advantages of the invention will become apparent from the following description of the accompanying drawings, in which a Nähorgangpaar of needle and gripper is shown in different positions relative to a Nähgutauflage. In the drawing show:

Fig. 1

the Nähorganpaar in side view in a first position to form a chain stitch,

Fig. 2

the Nähorganpaar according to Fig. 1 in a second position for performing a chain stitch;

Fig. 3

the Nähorganpaar according to the Fig. 1 and 2 in a third position after cutting an upper thread;

Fig. 4

the Nähorganpaar according to the Fig. 1 to 3 in a fourth position just before cutting a lower thread;

Fig. 5

the Nähorganpaar according to the Fig. 1 to 4 in a fifth position during the cutting process of the lower thread and

Fig. 6

another position of the Nähorganpaares according to the Fig. 1 to 5 for setting a remaining thread length before cutting the lower thread.

Regarding the Fig. 1 Below are the essential, necessary for explaining the invention construction elements of a sewing machine and described, then to the same reference numerals with respect to the other Fig. 2 to 6 Reference is made.

Fig. 1 shows a Nähgutauflage 1, on which a fabric 2, for example, a multi-layer fabric is placed, which is movable relative to the fabric support 1.

Above the Nähgutauflage 1 a needle 3 is arranged, which is reciprocally movable between two positions back and forth, wherein a position in Fig. 1 and a position in the Fig. 2 to 6 is shown. In the in Fig. 1 shown position of the needle 3, the needle 3 is inserted into the fabric 2 and passes through the Nähgutauflage 1, which has an opening not shown for this purpose.

The needle 3 has in its needle tip 4 a needle eye 5, through which an upper thread 6 is guided, for better visibility in all Fig. 1 to 6 is dashed.

To distinguish this is a lower thread 7, which will be described below in terms of its course and which is shown in phantom for better distinctness from the upper thread 6.

Fig. 1 further shows a arranged below the fabric support 1 gripper shaft 8 to which a gripper holder 9 is releasably attached. The gripper holder 9 has a bore 10, in which a substantially L-shaped gripper 11 is inserted with a spigot 12 in the region of a first leg 13. The gripper 11 is locked by a locking screw in the bore 10, which is screwed into a corresponding bore 14 having a thread.

The gripper holder 9 itself is also substantially L-shaped and screwed to the gripper shaft 8 in the region of a rectangular cross-section clamping element.

The gripper 11 has a second leg 16 with a free end, which is referred to as the hook tip 17. In the region of this hook tip 17, a bore 18 is arranged, through which the lower thread 7 is guided.

Furthermore, a cutting tool 19 is provided, which is screwed to the gripper holder 9. The cutting tool 19 is connected downstream of the gripper, wherein the term "downstream" refers to a direction of movement of the gripper during the usual sewing operation in the direction of the hook tip 17.

The cutting tool 19 consists of two blades 20, which is screwed together with the inclusion of an acute angle to each other by means of a screw 21 with a cutting tool holder 22. The cutting tool holder 22 is in turn screwed by means of a screw 23 with the gripper holder 9.

The two blades 20 of the cutting tool 19 can be changed after loosening the screw 21 in its angular position relative to each other, so that there is a more or less large angle between the facing blades 20, whereby the blades 20 and thus the cutting tool 19 to parameters of Under thread, such as thread thickness and thread material can be adjusted.

Fig. 1 shows a common starting position when sewing a chain stitch. The gripper 11 engages with its gripper tip 17 in the needle thread loop of the upper thread 6 and connects the guided from the gripper lower thread 7 with the upper thread 6. Subsequently, the needle 3 in the in Fig. 2 shown top position, causing the needle thread loop slides over the leg 16 of the gripper 11. In the usual sewing process, the gripper 11 is then in a position substantially according to Fig. 1 swung back and the needle 3 stabs again with the upper thread 6 through the fabric 2, before the gripper 11 again from the in Fig. 1 position shown in the in Fig. 2 shown position is pivoted.

In Fig. 3 a position of the gripper 11 is shown, in which the gripper 11 via the position according to Fig. 2 is swung out to cut the upper thread 6 by means provided in the transition of the legs 13 and 16 cutting tool 24. The lower thread 7 is hereby tensioned.

Now, if the gripper 11 is further pivoted in the clockwise direction, the lower thread 7 reaches a position between the two blades 20 of the cutting tool 19. It is now sufficient for a slight further pivoting of the gripper 11 according to Fig. 5 to cut the lower thread by means of the cutting tool 19. Additionally and / or alternatively it can be provided that in a position of the gripper 11 according to Fig. 4 the fabric 2 is moved in the direction of an arrow 25, so that also thereby the lower thread 7 is pulled into the V-shaped recess between the blades 20 and cut on the blades 20.

In both cases, the bobbin thread is cut with a length sufficient to avoid opening the stitch. Subsequently, the fabric can then be moved to a new position relative to the needle 3, for example, to begin a new pattern of material.

Fig. 6 shows in addition the basic possibility by moving the material 2 relative to the fabric support 1 to adjust the remaining thread length of the lower thread 7, but also the upper thread 6, so that the lower thread 7 is cut with a sufficient, remaining on the fabric 2 length. In Fig. 6 In addition, a presser foot 26 is shown.

Adjusting the remaining thread length of the lower thread 7 according to Fig. 6 is not limited to the illustrated position of the gripper 11 relative to the fabric 2. A corresponding displacement of the material 2 relative to the Nähgutauflage is of course possible in the positions of the gripper 11, as in the Fig. 3 to 5 are shown.

LIST OF REFERENCE NUMBERS

1 Nähgutunterlage 2 workpiece 3 needle 4 pinpoint 5 eye of a needle 6 upper thread 7 lower thread 8th gripper shaft 9 Out Holders 10 drilling 11 grab 12 spigot 13 leg 14 drilling 15 clamping element 16 leg 17 hook tip 18 drilling 19 cutting tool 20 blade 21 screw 22 Cutting tool holder 23 screw 24 cutting tool 25 arrow 26 presser

Claims (12)

1. A method for operating a double in-and-out stitch sewing machine, preferably a multi-needle double in-and-out stitch sewing machine which comprises a pair of sewing organs composed of a needle stitching into a sewing fabric and a bobbin shuttle placed beneath a sewing fabric support, wherein an upper thread is guided through the sewing fabric which rests upon the sewing fabric support by means of the needle, which upper thread is connected, especially linked to a lower thread, wherein the bobbin shuttle is moved along an oscillating motion path and wherein
   the lower thread (7) is cut by means of a cutting tool (19) if required, which cutting tool is displaced by a movement that is at least mostly not parallel to the sewing fabric support (1), in particular along a motion path which is shaped like a circular arc segment corresponding to a motion path of a swing of the bobbin shuttle (11).
2. A method according to claim 1,
   characterized in that
   the cutting tool is moved by means of a hook shaft (8) comprising the bobbin shuttle (11).
3. A method according to claim 1,
   characterized in that
   the cutting tool (19) is moved into the area of the lower thread (7) during the cutting operation, in particular until at least one cutting surface is adjacent to the lower thread, and the cutting operation is carried out by a movement of the sewing fabric (2) with respect to the sewing fabric support (1) and/or by a complementary movement of the cutting tool (19).
4. A method according to claim 1,
   characterized in that
   the cutting tool (19) is moved together with the bobbin shuttle (11).
5. A method according to claim 1
   characterized in that
   during the sewing operation, the cutting tool (19) and the bobbin shuttle (11) are moved on a motion path in form of a circular arc segment into an area in which the cutting tool (19) does not get into contact with the lower thread (7) and that the cutting tool (19) and the bobbin shuttle (11) are moved along the motion path into the same direction of movement over the said area for carrying out the cutting operation.
6. A method according to claim 1,
   characterized in that
   the upper thread (6) is cut by means of a cutting tool if required, which cutting tool is disposed in the area of the bobbin shuttle (11) or a spreader.
7. A method according to claim 6,
   characterized in that
   the upper thread (6) is cut independently from the lower thread (7).
8. A double in-and-out stitch sewing machine, preferably a multi-needle double in-and-out stitch sewing machine comprising a pair of sewing organs composed of a needle stitching into a sewing fabric and a bobbin shuttle placed beneath a sewing fabric support and movable along a motion path, wherein the needle guides an upper thread through the sewing fabric which rests upon the sewing fabric support and the upper thread is connected, especially linked to a lower thread, wherein the bobbin shuttle is movable along an oscillating motion path and wherein
   a cutting tool (19) is provided which cuts the lower thread (7) if required and which is displaceable by a movement that is at least mostly not parallel to the sewing fabric support (1), in particular along a motion path which is shaped like a circular arc segment corresponding to a motion path of a swing of the bobbin shuttle (11).
9. A sewing machine according to claim 8,
   characterized in that
   the bobbin shuttle (11) is disposed in particular in a replaceable manner on a bobbin shuttle holder (9) and that the bobbin shuttle holder (9) is connected to a hook shaft (8) driven in an oscillating manner and complementarily comprises the cutting tool (19) which is also preferably connected to the bobbin shuttle holder (9) in a replaceable manner.
10. A sewing machine according to claim 8,
    characterized in that
    the cutting tool (19) comprises two blades (20) which are connected to each other while including an acute angle between them, wherein the angle is preferably settable.
11. A sewing machine according to claim 8,
    characterized in that
    the bobbin shuttle (11) is essentially L-shaped and thus comprises two legs (13, 16) and that the bobbin shuttle (11) comprises a cutting tool (24) for cutting the upper thread (6).
12. A sewing machine according to claim 11,
    characterized in that
    the cutting tool (24) for cutting the upper thread (6) is placed in particular in a replaceable manner in the transition area of the two legs (13, 16) of the bobbin shuttle (11).

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