EP2253753B1 - Method for sewing a sewn item - Google Patents

Description

The present invention relates to a method for sewing a material, in particular from at least two, preferably large fabric layers by means of an upper and a lower thread, for example with lockstitch machines, in which a needle penetrates into the fabric with the upper thread and the upper thread is connected to the lower thread , whereupon the needle is withdrawn from the fabric.

Generic methods are known from the prior art.

In these methods, for example, fabric layers are removed from stocking facilities and provided for processing by the sewing unit. The sewing unit may have a Nähgutauflage with a above the Nähgutauflage arranged presser foot and a needle bar, in which a plurality of needles are arranged. Below the sewing material support designed as a perforated plate, the sewing unit has a number of grippers, in particular corresponding to the number of needles, which are fastened to a gripper bar. Grippers and needles are moved in an oscillating manner in order to carry out, for example, chain stitches or double chain stitches or the like in the sewing material resting on the sewing material support. The material to be sewn is preferably provided by the storage device in the form of unwinding from a roll of material. In this case, a separate roll of material is provided for each material layer.

A storage device discloses, for example, the DE 203 17 988 U1 , in which arranged according to the number of fabric layers horizontally one behind the other Material rolls are arranged. In a frame, a guide device is arranged for each roll of material, in which the respective roll of material of the fabric support is inserted. Such a guide device allows the storage of the roll of material with its lateral surface on a conveyor belt.

Vertically above each roll of material, a further roll of material is provided by means of a lifting device, so that the lower roll of material can be replaced by lowering the arranged above her roll of material, as soon as the fabric of the lower roll of material has been completely unwound or should be changed.

Although this storage device has already advantages in terms of set-up times and manual handling of difficult in practical operation material rolls, but is still not a satisfactory solution, since, for example. The change of fabric layers within different batches is still time-consuming.

In addition, methods for sewing a sewing material, in particular from at least two, preferably large-area fabric layers by means of an upper and a lower thread are known. Such methods are carried out, for example, on lockstitch machines, preferably lockstitch machines, in which a needle with the upper thread penetrates into the sewing material and the upper thread is connected to the lower thread. For this purpose, a gripper engages with the lower thread in a loop formed during retraction of the needle through the upper thread, whereupon the connection between upper thread and lower thread is made. When applying or after cutting the upper and lower thread after finishing the seam arise in the region of both surfaces of the sewing thread ends, which are usually cut off manually. This process is time-consuming and may result in damage to the material, for example if the material is damaged during cutting.

The DE 10 2007 017 235 A1 relates to a sewing machine with a thread trimming mechanism. This thread trimming mechanism is used for the simultaneous cutting of upper and lower thread below a Nähgutauflage.

The DE 40 32 0552 relates to a needle thread holding device for holding the leading end of the needle thread in a sewing machine with a thread cutting device. The thread trimming device is arranged below a Nähgutauflage the sewing machine and serves the simultaneous cutting of needle thread and bobbin thread.

The invention has for its object to improve a generic method for sewing a material with regard to the removal of yarn ends.

As a solution is proposed with the invention that the upper thread is stretched so that the lower thread connected to the upper thread is drawn with its end facing the fabric to above a needle facing surface, so that the end of the lower thread in the region of this surface is removable ,

By the method according to the invention, it is possible that the thread ends occur only on one surface, so that an opposite side of the material is formed on the production side without thread ends. This makes it possible to significantly reduce the effort for the removal of thread ends, since only a single surface of the material to be treated with respect to the removal of the thread ends. The method is particularly suitable for lockstitch machines in which by suitable control, the end of the lower thread can be pulled in a simple manner with the help of the upper thread to the needle-facing surface. Provided, for example, be that for this purpose the upper thread is acted upon during the passage of the lower thread with a higher tensile stress. This can be achieved, for example, by the fabric being transported, so that an additional tension is applied to the upper thread, so that the lower thread with its end facing the fabric is pulled onto the surface facing the needle.

A further development provides that the bobbin thread is cut off before the tensioning of the upper thread at the end of a sewing section. In this way, a reliable separation of the lower thread can be achieved without the lower thread is subjected to an additional voltage, such as occurs when torn off. This allows the sewing result to be protected from damage. The lower thread can be cut off by means of a suitable knife, a pair of scissors or the like. The cutting can be done automatically, so that manual intervention can be largely avoided.

The upper thread can be tensioned by moving the sewing material relative to the needle. As a result, a simple controlled introduction of a tensile stress in the upper thread can be achieved. In particular, the size of the tension can be adjusted accurately in a simple manner. Advantageously, only such a large tensile stress is introduced into the upper thread, which is required to pull the end of the lower thread on the surface facing the needle. Too high tensile stresses in the upper thread could lead to a tearing of the upper thread.

In addition, it can be provided that the upper thread is tensioned by means of a tensioning device, in particular a tensioning lever. The tensioning device can be automatically controlled so that it generates a tension in the upper thread at a given time at which the end of the lower thread is to be pulled through the fabric. The clamping device may for this purpose have a clamping lever, which is preferably actuated by means of a drive. The drive can be an electric, pneumatic or hydraulic drive.

Furthermore, the portion of the lower thread projecting beyond the surface is cut substantially flush with the surface, in particular cut off. The separation can be carried out for example by tearing off. Advantageously, however, the protruding part of the lower thread is cut off so that as far as possible no undesired tensile forces can occur on the lower thread. The clipping also makes it possible to specify the location or the length of the separation exactly. Especially with a substantially flush with the surface provided separation, the cutting proves to be advantageous because it can be done simply and accurately on the one hand by means of a cutting knife and the second end of the thread end of the lower thread flush with the surface. There is thus no thread end protruding from the surface.

It can also be provided that the lower threads are cut off with a maximum length of 10 mm. This embodiment proves to be advantageous if it is to be avoided that the seam can be solved. Due to the predetermined length, the automatic dissolution of a seam is largely avoided.

Furthermore, it can be provided that the cutting off of the portion of the lower thread projecting beyond the surface is carried out with at least one flat-type cutting device. With the cutting device, a predefinable length of the over the surface of the protruding part of the lower thread can be achieved in a simple manner. The flat-type cutting device can be designed, for example, in the form of a cutting head or the like. The cutting head may for example have a support surface which is to be applied to the surface. Laterally projecting blades can grasp and cut off the end of the over-surface portion of the lower thread, preferably to a predetermined length that can be adjusted on the cutting head. For example, the length may be 10 mm. But it can also be provided that the cutting head cuts off the end of the lower thread flush with the surface.

Preferably, substantially each needle or pair of pins becomes one

Assigned to cutting device. In this way, the invention can be used for each seam to be produced.

Furthermore, the upper threads running on the surface and not sewn to the sewing material can preferably be cut centrally. This allows to remove the unsewn upper threads also from the fabric. It can be provided that the cutting is also carried out by means of the aforementioned cutting device. In addition, however, it may also be provided a separate cutting blade, which engages the upper thread on the surface and cuts substantially in the middle. In this way, individual seams of the sewing material can be separated.

Advantageously, the cut upper threads are cut off with the flat cutting device. Thus, preferably at the same time as the ends of the lower threads, the cut ends of the upper threads can also be removed. A simple, fast and reliable removal of thread ends can be achieved. Manual interventions can essentially be completely avoided.

Further advantages and features can be found in the following description of exemplary embodiments. Substantially identical components are designated by the same reference numerals. Furthermore, with regard to the same features and functions, reference is made to the description of the exemplary embodiment Fig. 2 directed. The drawings are schematic drawings and are merely illustrative of the following embodiment.

Fig. 1

ein Nähaggregat mit einer Bevorratungseinrichtung des Standes der Technik in einer schematischen Seitenansicht;

Fig. 2

eine perspektivische Ansicht eines Nähaggregats mit einer Bevorratungseinrichtung der Erfindung;

Fig. 3

eine schematische Seitendarstellung der Bevorratungseinrichtung nach Fig. 2;

Fig. 4

einen Ausschnitt einer Rollenaufnahme der Bevorratungseinrichtung gemäß Fig. 3 mit zwei übereinander angeordneten Materialrollen in einer Seitenansicht;

Fig. 5

die Rollenaufnahme nach Fig. 4 mit einem teilweise seitlich herausgefahrenen Halter und

Fig. 6

die Rollenaufnahme nach Figuren 4 und 5, mit einem in einer seitlich gekippten Stellung angeordneten Halter.

Show it:

Fig. 1

a sewing unit with a storage device of the prior art in a schematic side view;

Fig. 2

a perspective view of a sewing unit with a storage device of the invention;

Fig. 3

a schematic side view of the storage device according to Fig. 2 ;

Fig. 4

a section of a roll receiving the storage device according to Fig. 3 with two superimposed material rolls in a side view;

Fig. 5

the role recording after Fig. 4 with a partially laterally extended holder and

Fig. 6

the role recording after FIGS. 4 and 5 with a holder arranged in a laterally tilted position.

Fig. 1 shows a schematic side view of a storage device 10 for at least one sewing unit having sewing machine 14, are made with the mattress plates, which in the present case of three fabric layers 16, 18, 20 are each deducted from a roll of material 24, 26, 28. In the present case, the fabric layer 18 is made of elastic material, namely foam. The fabric layer 20 forms a cover layer. The fabric layer 16 is made of inelastic material.

The fabric layers 16, 18, 20 are deposited on each other when rolling and form the sewing material to be sewn, which is supplied to the sewing unit via non-designated guide rollers. The supply of the fabric layers 16, 18, 20 is provided by the force acting on the fabric. In the sewing unit, the fabric layers 16, 18, 20 deposited on each other are sewn together to form the sewing material. The material is discharged via non-designated guide or deflection rollers which provide, inter alia, a tightening of the material in the exit region of the sewing unit, and fed to further processing.

Above each of the material rolls 24, 26, 28, a spare roll is mounted in each case, which serves to replace the material roll arranged thereunder. For this purpose, first the corresponding roll of material 24, 26, 28 to remove, so that space for receiving the material roll arranged above it is created. The latter is then manually lowered to the position of the preceding roll of material 24, 26, 28. After a threading process, the production process of the sewing material can be continued.

In this prior art, it proves to be disadvantageous that at a required change at least one of the three Nähgutauflagen 16, 18, 20 or when one of the material rolls 24, 26, 28 has run empty, the corresponding roll of material 24, 26, 28th is to replace. For this, the sewing machine 14 must be stopped completely. The conversion requires a lot of time, especially because the material rolls are relocated.

Fig. 2 shows now a storage device 32 according to the invention with three roller supports 34. Each roller receptacle 34 has in the present case two holders 42, which are each arranged in pairs vertically above one another. In the present case, the three roller receivers 34 are arranged horizontally one behind the other, so that the respective material layers can be deposited on one another during the removal of material rolls 24, 26, 28, 36, 38, 40 arranged in the holders 42.

Each holder 42 receives a respective material roll 24, 26, 28, 36, 38, 40. Each of the material rolls 24, 26, 28, 36, 38, 40 is rotatably mounted on its respective holder 42. Fig. 3 shows the storage device in a schematic side view.

The holders 42 are part of the roller holder 34. Of the arranged in one of the roller holder 34 material rollers 24, 26, 28, 36, 38, 40, the corresponding fabric layers are removable and the sewing unit can be fed. The sewing unit is in the present case a sewing unit, as previously stated with respect to the prior art. The holders 42 of the roller holder 34 are arranged substantially horizontally next to one another.

In the holders 42 of the roller receptacle 34, essentially the same or at least material similar to the essential properties for the sewing process is presently supported. Thus, upon reaching one end of a rolled on the material roll 24, 26, 28, 36, 38, 40 first fabric layer directly on the vertically adjacent roll of material 24, 26, 28, 36, 38, 40 are switched by only a beginning of the second Fabric layer of the vertically adjacent roll of material is connected to the end of the first fabric layer.

How out Fig. 3 it can be seen, each holder 42 has two spaced apart cantilevers 44 and extending between the cantilevers 44 axis of rotation 46 for receiving the respective roll of material 24, 26, 28, 36, 38, 40th

Each of the holders 42 has a plurality of rollers 48, which are rotatably mounted in the holder 42 and on which the roll of material 24, 26, 28, 36, 38, 40 can be placed. This can be on the rollers 48 resting material roll axially in the longitudinal direction of the holder 42 are moved without much effort. This configuration makes it possible to replace not only the material roll 24, 26, 28, 36, 38, 40 simplified, but it also allows the roll of material 24, 26, 28, 36, 38, 40 to adjust in its axial position.

In the present embodiment, it is further provided that the storage device 32 consists of three roller receivers 34, which are each formed adjacent to each other for receiving two material rolls 24, 26, 28, 36, 38, 40 in a substantially vertical plane, so that rotation axes 46 the material rolls 24, 26, 28, 36, 38, 40 are aligned substantially parallel to each other. Fig. 4 shows the roller receptacle 34 for the material rolls 16 and 24th

It is further provided that in each case the upper holder 42 of the roller receptacle 34 has a receiving device 50 with which a roll of material 24, 26, 40 can be conveyed into the respective upper holder 42 ( FIGS. 4 to 6 ). For this purpose, the receiving device 50 has a carriage 52 which has a bearing surface 54 which can be placed on the material roll 24, 26, 40. The carriage 52 is movable relative to the holder 42 between an inserted and an extended position and formed in an aligned with the extended position end position relative to the holder 42 angled ( FIGS. 5 and 6 ).

Like from the FIGS. 5 and 6 it can be seen, the carriage 50 can be pivoted about an axis 56, so that it can be bent in the extended end position to the holder 42 such that the roll of material 24, 26, 40 simply removed or. can be used.

In the present case, the carriage 52 is formed in longitudinal section L-shaped. The carriage 52 forms a leg 58 as a supporting system for the roll of material 24, 26, 40. As a result, in the extended and tilted end position, the roll of material 24, 26, 40 are replaced in a simple manner.

The support surface 54 is presently formed of a plurality of rotatably mounted in the carriage 52 rollers 48. By the rollers 48, the roll of material 24, 26, 40 can be moved in the retracted position of the carriage 52 without great effort in the desired axial position.

Between the carriage 52 and the receiving device 50, a linear motor 60 is articulated, with which the carriage 52 can be moved between the retracted and the extended position. A manual intervention for positioning the carriage 52 can thus be substantially saved. The arrangement of the carriage 52 and the articulation of the linear motor 60 also allows the carriage 52 can be tilted during its movement at the same time also in the appropriate position. An ejection of the carriage 52 thus also causes at the same time tilting about the axis 56, so that with a single drive the carriage 52 can be moved from its material preparation position in its role change position (see. 4 to 6 ).

The linear motor 60 is designed as a pneumatic cylinder. In addition, the linear motor can of course also be designed as a hydraulic cylinder or by using a tension spring as an energy storage.

The roller holder 34 has a support frame 62, on which the holder 42 are formed as two spaced apart with the support frame 62 cantilevers 44, between which a roll of material 24, 26, 28, 36, 38, 40 is rotatably mounted. In the cantilevers 44, a rod as a rotation axis 46 can be inserted, which rod or roller, the material roll 24, 26, 28, 36, 38, 40 passes through centrally.

In order to replace the roll of material 24, 26, 28, 36, 38, 40, a respective cantilever 44 of each holder 42 is displaceable relative to the support frame 62, namely formed about an axis parallel to the axis of rotation 46 extending axis. This makes it possible to pivot away the respective cantilever arm 44 preferably downwards, so that the carriage 52 is released for movement of the respective material roll 24, 26, 40 in the axial direction with the material roll 24, 26, 40 placed thereon.

From the Figures 2 and 3 It can also be seen that in each case two holders 42 of a roller receptacle 34 are assigned a connecting and guiding device 64 for the material layers to be deducted from the material rolls 24, 26, 28, 36, 38, 40. This makes it possible to fix a beginning or end of a fabric layer of a respective non-operational material roll. For this purpose, the connecting and guiding device 64 has two spaced-apart clamping devices with which the respective material layer can be clamped. Not shown is that each clamping device has at least one relative to the fabric position pivotable roller.

• Aus der Bevorratungseinrichtung 32 werden Nähgutlagen 14, 16, 18 einer ein Nähaggregat aufweisenden Nähmaschine 14 zum Zwecke des Vernähens zugeführt. Die Bevorratungseinrichtung 32 weist hierfür sechs Materialrollen 24, 26, 28, 36, 38, 40 auf, von denen jeweils Nähgutlagen 16, 18, 20 abgezogen werden können. Die Materialrollen 24, 26, 28, 36, 38, 40 sind paarweise in Rollenaufnahmen 34 vertikal übereinander angeordnet.

The method sequence for feeding a material layer is described below:

• From the stocking device 32, fabric layers 14, 16, 18 are fed to a sewing machine 14 having a sewing unit for the purpose of stitching. For this purpose, the storage device 32 has six material rolls 24, 26, 28, 36, 38, 40, from each of which material layers 16, 18, 20 can be pulled off. The material rolls 24, 26, 28, 36, 38, 40 are arranged in pairs in roll receptacles 34 vertically above one another.

As Fig. 2 shows, it is provided that the material rolls 24, 26, 28 provide fabric layers 16, 18, 20, which are stored on each other and the sewing unit via unspecified deflection and guide rollers are supplied. The fabric layers 16, 18, 20 are sewn in this case to mattress panels. Two material rolls 24, 26, 28, 36, 38, 40 with material layers 16, 18, 20 are arranged in the storage device 32 in two holders 42 of a roll receptacle 34, wherein a first fabric layer 16, 18, 20 of a holder 42 of the roll receiving 34 withdrawn and the sewing machine 14 is supplied.

If necessary, the above or below the first fabric layer 16, 18, 20 arranged fabric layer 16, 18, 20 deducted from the respective second roll of material 24, 26, 28, 36, 38, 40 in the second holder 42 of the corresponding roll holder 34 and the Sewing machine 14 are supplied. For this purpose, the second fabric layer 16, 18, 20 is connected to the end of the first fabric layer 16, 18, 20. For this purpose, the first fabric layer 16, 18, 20 can be cut off at its end substantially perpendicular to its longitudinal extent prior to connection to the second fabric layer 16, 18, 20, to form a straight edge.

The ends to be joined together are butted against each other and connected to each other with an adhesive strip both ends. By continuing the production process, the second material layer 16, 18, 20 is thus automatically conveyed through the first material layer 16, 18, 20 to the sewing unit for the continuation of the sewing process. Assembly operations for exchanging material rolls 24, 26, 28, 36, 38, 40 can thus be reduced to a minimum or take place independently of the respective production process. The fabric layers 16, 18, 20 are stored in the form of material rolls 24, 26, 28, 36, 38, 40 in the roll receptacle 34 one above the other. Material rolls 24, 26, 28, 36, 38, 40 arranged in the holders 42 of a roll receptacle 34 have the same or at least similar materials with regard to the essential properties for the sewing process.

In order to be able to achieve a good connection of the ends of the fabric layers 16, 18, 20 to be joined, the fabric layers 16, 18, 20 to be joined together are fixed relative to one another in the position prior to joining their ends. Among other things, for this purpose, the material rolls 24, 26, 28, 36, 38, 40 are shifted in their axial position to each other.

In the Figures 2 and 3 are additionally two rolls of material 92, 94 shown, which are also arranged in a roll receiving, wherein it is the material rolls 92 and 94 so-called cover sheet material, which is arranged and sewn in the production of, for example, quilts or mattress tops as the top layer. In the production of quilts or mattress boards often a frequent change between these cover layer materials is required in order to be able to sew corresponding pre-planned batches of different design. Therefore, the above-described advantages of the storage device 10 according to the invention also apply to a storage device 10 with a roll receptacle for this cover layer material according to the material rolls 92 and 94. It is in the Figures 2 and 3 to recognize that these rolls of material 92 and 94 are mounted in the immediate vicinity of the sewing machine 14 in the roll receptacle 22, so that this cover sheet material is also provided in close proximity to the sewing unit. It should again be noted that all features of the roller mount 22, as used in the storage device 10 according to the Figures 2 and 3 shown and described above are also in terms of the material rolls 92 and 94 in the space provided for this purpose roll receptacle 22 may be provided immediately before the sewing machine 14. This also achieves the advantages described above in this area.

Figuren 7 bis 11

schematische Verfahrensschritte eines Nähvorgangs und zum Fadenabschneiden einer Steppstichmaschine;

Fig. 12

einen Abschnitt eines Nähguts mit einem gespannten Oberfaden in perspektivischer Ansicht;

Fig. 13

eine Schneideinrichtung zum Abschneiden von Fadenenden in perspektivischer Ansicht; und

Fig. 14

die Schneideinrichtung gemäß Fig. 13 in einer Draufsicht.

A sewing process will be described with reference to the following figures. Show it:

FIGS. 7 to 11

schematic process steps of a sewing process and the Thread trimming a lockstitch machine;

Fig. 12

a section of a fabric with a tensioned upper thread in perspective view;

Fig. 13

a cutting device for cutting thread ends in a perspective view; and

Fig. 14

the cutting device according to Fig. 13 in a top view.

From the FIGS. 7 to 11 is a method for sewing material to be seen 72, which is formed of two large fabric layers 16, 18 which are connected by means of an upper and a lower thread 66, 68. In the method, a needle 70 of a sewing unit not shown penetrates into the sewing material 72 with the upper thread 66. The upper thread 66 is connected to the lower thread 68, whereupon the needle 70 is withdrawn from the fabric 72 ( Fig. 7 ).

In order to separate the lower thread 68 from the sewing material 72, a cutting device 74 is arranged below the sewing material 72, that is, in the region of the surface of the sewing material 72 facing away from the needle, which cuts off the lower thread 68 (FIG. Fig. 8 ). After the lower thread 68 is cut off and a free end 78 is formed, the fabric 72 is displaced in the transport direction, whereby the upper thread 66 is tensioned such that the lower thread 68 connected to the upper thread 66 facing with its free end 78 to above one of the needle 70 Surface 76 is pulled so that the end 78 of the lower thread 68 in the region of this surface 76 is removable. The lower thread 68 is cut off before tensioning the upper thread 66 at the end of a sewing section. Alternatively, to move the sewing material 72, a tensioning of the upper thread 66 by an independent, not shown tensioning lever done ( Fig. 9 ).

The now over the surface 76 protruding free end 78 of the lower thread 68 is cut substantially flush with the surface 76. For this purpose, a cutting device 80 is provided, which will be described below ( FIGS. 13, 14 ). For example, the lower threads 68 are cut off such that their free ends 78 projecting beyond the surface 76 have a maximum length of 10 mm. The cutting of over the surface 76 protruding part of the Lower thread 68 is executed with a flat cutting device 80. It is contemplated that substantially each needle 70 is associated with a cutter 80.

According to a further embodiment it is provided that also the upper thread 66 is cut when it rests on the surface 76 due to a transport of the material 72 between the end of a seam and the beginning of a following seam ( Fig. 10 ).

By means of a knife 82, the upper threads 66 running on the surface 76 and not sewn to the sewing material 72 are cut substantially centrally ( Figures 11 and 12 ).

For this purpose, the knife 82 movable transversely to the transport direction has a cutting edge 84. The cutting edge 84 is inclined relative to the surface 76 and runs at an acute angle to this. As a result, can be detected with the tip of the upper thread 66 and cut over a sliding movement over the cutting edge 84. As a result, yarn ends 86 of the upper thread 66 are generated. The thread ends 86 can then together with the thread ends 78 of the lower thread 68 in one operation by means of the cutting device 80 (FIG. FIGS. 13 and 14 ) are cut off. Optionally, the yarn ends of the lower threads and / or the upper threads are blown or sucked with air, so that a safe cutting process is given ..

Even at the beginning of a seam is provided that the lower thread 68 is pulled by means of the upper thread 66 on the needle 70 facing surface 76.

The cutting device 80 has two flat-shaped cutting plates 88, which are arranged substantially parallel to each other and slidable to each other. On one side, the two cutting plates 88 sawtooth-like projections in the form of a sawtooth profile 90, which cause in the case of displacement of the cutting plates 88 along the extension of the sawtooth 90 against each other at their adjacent edges a cutting action. The cutter 80 is used for the purpose of cutting the yarn ends 78, 86 along the surface 76 of the fabric 72. By appropriate selection of the cutting plates 88, the length of the thread ends 76, 86 can be adjusted.

The exemplary embodiments illustrated in the figures merely serve to explain the invention and are not restrictive of it.

LIST OF REFERENCE NUMBERS

10

stocker

14

sewing machine

16

sewing material

18

sewing material

20

sewing material

22

roll cradle

24

material roll

26

material roll

28

material roll

32

stocker

34

roll cradle

36

material roll

38

material roll

40

material roll

42

holder

44

cantilever

46

axis of rotation

48

role

50

recording device

52

carriage

54

bearing surface

56

axis

58

leg

60

linear motor

62

supporting frame

64

Connecting and guiding device

66

upper thread

68

lower thread

70

needle

72

workpiece

74

cutter

76

surface

78

End of the lower thread

80

cutter

82

knife

84

cutting edge

86

End of the upper thread

88

cutting boards

90

sawtooth

92

material roll

94

material roll

Claims (10)

1. A method for machine sewing a sewn fabric (72), in particular composed of at least two sewn fabric layers (16, 18) that preferably present large surfaces, by means of an upper thread and an under-thread (66, 68), for example using lockstitch machines, in which a needle (70) with the upper thread (66) penetrates into the sewn fabric (72) and the upper thread is connected to the under-thread (68), whereupon the needle is withdrawn from the sewn fabric (72),
   characterized in that
   the upper thread (66) is tensioned such that the under-thread (68) connected to the upper thread (66) is torn with its end facing the sewn fabric (72) to above one surface (76) that faces the needle (70), such that the end (78) of the under-thread (68) can be removed in the area of this surface (76).
2. A method according to claim 1,
   characterized in that
   the under-thread (68) is cut off at the end of a sewing section before tensioning the upper thread (66).
3. A method according to claim 1,
   characterized in that
   the upper thread (66) is tensioned in that the sewn fabric (72) is displaced with respect to the needle (70).
4. A method according to claim 1,
   characterized in that
   the upper thread (66) is tensioned by means of a tensioning device, in particular a tensioning lever.
5. A method according to claim 1,
   characterized in that
   the part of the under-thread (68) which protrudes over the surface (76) is separated, in particular cut off such that the under-thread (68) ends essentially flush with the surface (76).
6. A method according to claim 5,
   characterized in that
   the under-threads (68) are cut off with lengths of maximum 10 mm.
7. A method according to claim 5,
   characterized in that
   the cutting-off of the part (78) of the under-thread (68) which protrudes over the surface (76) is carried out by means of at least one cutting device (80) that works on the surface.
8. A method according to claim 7,
   characterized in that
   one cutting device is essentially allocated to each needle (70) or pairs of needles.
9. A method according to claim 1,
   characterized in that
   the upper threads (66) which extend on the surface (76) and are not sewn with the sewn fabric are preferably cut in the centre.
10. A method according to claim 9,
    characterized in that
    the cut upper threads (66) are cut off by means of the cutting device (80) that works on the surface.

Images