CN110892104A

CN110892104A - Sewing machine and sewing method for producing a stitch

Info

Publication number: CN110892104A
Application number: CN201880015277.8A
Authority: CN
Inventors: M·伊梅茨伯格
Original assignee: Pfaff Industriesysteme und Maschinen GmbH
Current assignee: Pfaff Industriesysteme und Maschinen GmbH
Priority date: 2017-02-16
Filing date: 2018-02-15
Publication date: 2020-03-17
Anticipated expiration: 2038-02-15
Also published as: DE102018001176A1; CN110892104B; EP3583261A1; WO2018149547A1; ES2939938T3; PT3583261T; EP3583261B1

Abstract

The invention relates to a sewing machine and a sewing method, comprising at least one double-chain stitch sewing machine for producing at least one seam on a sewing material, in particular for producing at least one fold on the sewing material, wherein the sewing machine is provided with a driven sewing material feed device for a determined or determinable feed direction of the sewing material relative to a stitch forming tool, the feed direction being suitable for producing at least one seam on the corresponding sewing material, wherein the sewing material feed device has a pressure lever (18) by means of which the sewing material can be pressed against a table plate and moved past the stitch forming tool in order to produce the feed movement. In order to achieve a stitch-free incorrect start of the seam when using such a sewing device for producing a stitch without requiring manual reworking, and still achieve a short yarn start, the invention proposes that a clamping device (25) is provided on the pressure lever (18) and can be moved with the pressure lever (18) in its feed movement, wherein the clamping device (25) is suitable for clamping the yarn start of the upper thread (30), and that the sewing device has a cutting element (34) which is arranged at least temporarily in the region between the clamping device and the presser foot immediately after the start of the stitch-producing operation in order to cut off the upper thread between the clamping device and the presser foot.

Description

Sewing machine and sewing method for producing a stitch

Technical Field

The invention relates to a sewing machine, comprising at least one double-chain stitch sewing machine for producing at least one seam on a sewing material, in particular for producing at least one fold on the sewing material, wherein the sewing machine is provided with a driven sewing material feed device for a determined or determinable feed direction of the sewing material relative to a stitch forming tool, the feed direction being suitable for producing at least one seam on the corresponding sewing material, wherein the sewing material feed device has a pressure lever by means of which the sewing material can be pressed against a sewing table and the sewing material is moved past the stitch forming tool in order to produce the feed movement.

Background

In some sewing materials, it is necessary to add so-called darts by inserting at least one straight or curved running seam. The function of the tuck is usually to change the contour extension of the corresponding item of clothing, for example to sew a shirt or a lady shirt close to the waistline. In the industrial production of garments, such darts imply an additional sewing operation, which is usually carried out in the industrial production separately, i.e. independently of other sewing operations on the garment. Therefore, in order to produce the tucks, these tucks are generally produced by means of a dedicated sewing apparatus including a double-chain stitch sewing machine. For this purpose, the clothing items are therefore fed to a sewing machine for producing darts, where they are treated accordingly, and are subsequently conveyed to a machine for carrying out further subsequent processing steps.

With these sewing apparatuses, the sewing material is generally manually fed into the sewing apparatus. The feed of the relative stitch forming tool of the sewing material, in particular relative to the needle and the needle bar and relative to the hook of the sewing machine of the sewing device, is produced electrically, without intervention of an operator. To produce the tuck, the sewing material is usually fed linearly. Depending on the size of the material to be sewn and the length of the tuck, the length of the feed movement required may vary. To produce the feed movement, the sewing material is usually clamped to the table by means of a press bar, wherein the press bar is usually movable in the X-Y direction. After the sewing operation on the respective sewing material is finished, the sewing material is detected by the extraction device, and the sewing material is guided out of the sewing device in the feeding direction of the sewing operation and stored on the stacking point.

It is often difficult to produce an error-free stitch start of a double lock stitch. In order to avoid false stitch formation, in particular to avoid the so-called nest (dent), the end of the upper thread that protrudes from the needle must have a certain minimum length. However, in the case of a relatively long free yarn end, the upper thread end may be drawn under the sewing material during sewing, thereby creating a thread pocket. Furthermore, the relatively long thread start projecting from the needle has the disadvantage that on the finished stitch, the thread start of the upper thread projects as a long thread start on the visible side of the sewing material. Since this long open end of the unseamed thread is recognized as a quality defect in the sewing material, which usually requires further processing, a subsequent shortening of the thread is usually carried out manually. This means that there is an additional high outlay in the production of such sewing materials.

Disclosure of Invention

In view of the above, the object of the invention is to provide a solution for achieving a stitch-free, wrongly formed stitch start during a tuck stitch and still a short yarn start without requiring a manual reworking for this purpose.

With regard to a sewing machine of the type mentioned at the beginning, the solution of the invention for achieving the object described above is characterized by the features of claim 1. Therefore, in the case of the sewing machine according to the preamble of claim 1 of the present invention, a clamping device is to be provided on the presser bar and is movable together with the presser bar in its feed movement, wherein the clamping device is adapted to clamp, in particular (but not exclusively) the thread start of the upper thread, and the sewing machine has a cutting element which is arranged at least temporarily in the region between the clamping device and the presser foot immediately after the start of the seam generating operation for cutting off the upper thread between the clamping device and the presser foot. The solution of the invention to achieve the above object is also a method as claimed in claim 9. With this solution it is possible to avoid the yarn ends being pulled down under the sewing material during sewing and to achieve a finished stitch pattern even at the beginning of the stitch seam. With the advantages described above achieved with little technical effort, the seam still has a short yarn start, so that no subsequent shortening of the yarn start at the seam is necessary. By means of the invention, the thread start is shortened preferably shortly after sewing and in particular during the sewing operation, without the need to interrupt or delay the sewing operation for this purpose.

In a preferred embodiment, the sewing device has a switchable cutting element which can be extended into a region between the clamping device and the sewing material and retracted by at least one switching operation into the feed path of the upper thread on the sewing material in order to cut off the upper thread in this region. In this embodiment of the invention, the cutting element is located only briefly in the region of the sewing material, so that the risk of damage to the sewing material by the cutting element is kept as low as possible despite the severing operation being carried out against the sewing material.

In a preferred development of the invention, the cutting element can also be only a single blade edge, which contains preferably only one cutting edge which comes into contact with the needle thread by being arranged in the feed path of the sewing material. In this way, the feed movement of the sewing material (and of the upper thread already sewn) is utilized, so that the free yarn start is already shortened during the production of the stitch, without in this case having to interrupt the sewing operation itself and without having to carry out a cutting movement by means of the cutting element. Although an additional operation is carried out according to the invention when shortening the thread start in the same type of sewing process, the time required for carrying out the sewing process is not increased by means of this preferred embodiment of the invention. Furthermore, the relative movement between the cutting element and the upper thread, which results in the cutting of the upper thread, is also produced by means of the feed movement of the sewing material.

According to a particularly advantageous development of the invention, in order to produce a seam fold in a sewing material to be processed later, the upper thread is cut off during or after the sewing process for a seam fold in a previously processed sewing material, the previously processed sewing material is removed from the sewing device, the pressure lever is moved back into its receiving position, and the open clamping device is arranged in such a way that the free end of the upper thread is arranged in the clamping device as a result of the movement and positioning of the pressure lever, the clamping device is subsequently closed, and the sewing process for the sewing material to be processed is then started with the clamping device still closed. By means of this embodiment, it is possible to arrange the upper thread in the clamping device in a particularly fast and process-stable manner without the need to carry out a further processing step or to employ additional specific components for this purpose. In the case of this and all other embodiments of the invention, the term "presser bar" also refers to other pressure elements which are not strip-shaped and are used to clamp or press the sewing material against the working plate of the sewing machine. Furthermore, "stitch forming tools" are in particular pointers, needle bars guiding needles and shuttles, which are often used in particular for guiding upper threads and lower threads in double-lock stitch sewing machines.

Other preferred embodiments of the invention are described in the claims, the description and the drawings.

Drawings

The invention will be elucidated in detail on the basis of an embodiment which is shown purely schematically in the drawing, in which:

FIG. 1 is a perspective view of a sewing apparatus of the present invention incorporating a sewing material inserted into a feed device;

fig. 2 is a detail according to fig. 1 in the region of a sewing machine and in the region of a pressure lever of a sewing device in a starting position; but the sewing material is not shown;

FIG. 3 is a detail view of the drawing-off device of the sewing machine according to FIG. 2, with the presser bar in the "start of stitch" position;

FIG. 4 is a schematic view of the sewing apparatus of FIG. 2 in an operating condition with the clamping device clamping the open end of the yarn and the presser foot lowered;

FIG. 5 is another illustration of the sewing machine according to FIG. 2, wherein the cutting element is moved into the cutting position after the sewing process has started;

FIG. 6 is a partial view of the sewing apparatus of the present invention from another perspective after the start of the thread of the upper thread has been shortened and the cutting element has been pulled back;

fig. 7 is a further detail of the sewing machine in the region of the suction device provided for sucking off the separated thread sections.

Detailed Description

The embodiment of a sewing machine 1 for producing darts according to the invention shown in fig. 1 has a sewing machine 3 arranged on a work plate 2. The sewing machine 3 may be a conventional double chain stitch sewing machine. Such a sewing machine is equipped with a known stitch forming tool, which essentially comprises at least one needle for an upper thread, which is arranged on and guided by a needle bar, and a rotary hook (Umlaufgreifer) for a lower thread. In double-lock stitch sewing machines, the stitch forming operation is also carried out in a known conventional manner using a stitch forming tool.

As can be seen in particular from fig. 1, a sewing machine 3 containing stitch-forming tools is arranged in the region of a longitudinal edge 4 of the work plate 2 and transversely to this longitudinal edge 4. In the region of this longitudinal edge 4, starting from the corner 6 formed by the longitudinal edge 4 and the transverse edge 5 of the table, a feed table 7 is provided. The table of the feeder table is matched to the size of the blank 9 to be fed, which acts as sewing material. The feeder table 7 serves to receive the blanks 9 and then to feed the respective blanks 9 to a predetermined position on the work plate 2, from which the blanks 9 are then fed automatically to the sewing process. For this purpose, the feeder floor 7 can be moved towards the work plate 2 and reset, either manually or by motor drive.

Furthermore, in the region of the longitudinal edge 4 of the work plate 2, a material receiving device 10 and a sewing material feed device for the respective sewing material, which is referred to below as a feed device 11, are provided. The material receiving means 10 essentially have the function of assisting the orientation of the respective blank 9 with respect to its extension transverse to the longitudinal edges 4 during the sewing operation. The material receiving device has a drive 12 for translating a square 14 of the material receiving device, which extends parallel to the longitudinal edge 4 of the work plate 2, parallel to this longitudinal edge 4. In the present embodiment, the drive 12 is configured as a spindle stepping motor, whose rotary drive movement, via suitable gearing, causes a linear translational movement of the angle 14, so that the blanks can be arranged at different depths. This setting depth may be preset on the controller of the sewing device 1 so that the driver performs this input before a sewing operation or before a series of sewing operations.

In the region of the square 14, a needle bank 16 is provided which can be moved up and down by means of a pneumatic drive, the needles of which are aligned with corresponding receiving openings in the work plate 2, which are located directly in front of the horizontal side 14a of the square 14. The blank 9 can be held between the needle bank 16 and the work plate 2 by the downward movement of the needle bank 16.

The feeding device 11 is adapted to accommodate the sewing material 9 for the sewing operation and to feed the sewing material 9 during the sewing operation. The direction of feed 19 can extend at least in a linear direction parallel to the plane of the substantially flat top side of the work plate 2. In the present embodiment the feed direction 19 is movable in an X-Y plane parallel to the top side of the work plate 2. The feed device 11 of the present embodiment is provided with a presser bar 18 which is movable in a feed direction 19 for receiving the respective sewing material 9 and moving the sewing material relative to the stitch forming tool. In this way, the presser bar 18 can be moved in the feed direction 19 from a first end position, in which the sewing material is inserted and accommodated, to a second end position, in which the sewing material is extracted. The first terminal corresponds here to: the position the blank has when it is received by the feeding device 11 from the material receiving device 10 before the feeding device 11 is moved in the feeding direction 19. The second end position corresponds to: after the predetermined fabric has been inserted into the sewing material 9, the feed device 11 or the blank 9 has a position after the movement of the feed device 11 on the other side of the sewing machine 3 has ended.

The resetting is preferably performed along a direct path, i.e. along the distance line between the second end bit and the first end bit. In order to carry out the feed movement of the plunger 18, a drive, in particular an electric stepping motor, can be provided for each of the two feed directions. By superimposing the drive motions of the two stepper motors, any predetermined feed motion can be achieved in the X-Y plane.

The plunger 18, which in the illustrated preferred embodiment is constructed as an elongate member and is generally angular in cross-section, can be moved up and down by means of another suitable drive. In the present exemplary embodiment, this drive of the plunger 18 is designed as a pneumatic cylinder. By raising the presser bar 18 in the Z direction, a gap for accommodating or for subsequently extracting the sewing material 9 is released between the presser bar 18 and a counter plate (hereinafter referred to as a platen) provided below. By lowering the presser bar 18, the sewing material can be clamped between the platen and the presser bar 18. In the present embodiment, the top side of the work plate 2 serves as such a platen. The presser bar 18 is located in its first end position (as seen in the feed direction) substantially in front of the sewing machine 3 and its stitch forming tool, at least by means of a section for accommodating the sewing material, so that the respective sewing material 9 can be arranged and clamped in a predetermined manner in front of the stitch forming tool before the start of the sewing operation. In the sewing operation, the presser bar 18 is moved towards the second end position and in this case carries the sewing material 9 and delivers it to the stitch forming tool for forming the fabric seam. In the second end position, the presser bar 18 is located behind the sewing machine and its stitch forming tool together with the sewn sewing material.

As can be seen in particular from fig. 2 and 3, a clamping device 25 is attached to the pressure lever 18 and is movable with the pressure lever 18 in the feed movement. The clamping device 25 is arranged on the pressure bar 18 in such a way that the X-direction of the clamping device 25 relative to a possible feed movement lies at least approximately at the level of the pressure foot 28. Furthermore, the clamping device 25 has a clamping element 26, which has a flat clamping surface, which can be pressed against a counter-clamping element 27. The clamping elements 25 can be automatically pressed against the counter-clamping element 27 and lifted again by means of an actuator, for example an electric motor or a pneumatic actuator, which corresponds to the clamping elements one to one. By means of this movement, the free thread start 30a of the upper thread 30 passing through the needle 29 can be pressed by the clamping element 26 against the counter-clamping element 27.

As can also be seen from fig. 2 and 3, the sewing apparatus is provided with a cutting device 33 for shortening the yarn start 30a of the upper thread 30. The cutting device 33 has a cutting element 34 embodied as a blade, the cutting edge 35 of which extends substantially transversely to the X-feed direction. The cutting edge 35 is formed here on the side edge of the cutting edge which is the rear side edge with respect to the X-feed direction. Furthermore, the cutting element 34 is assigned a drive corresponding thereto, by means of which drive the cutting element 34 can be retracted and extended in the vicinity of the needle substantially transversely to the X-feed direction and parallel to the Y-feed direction.

In order to produce a tuck (the course of the seam to be produced of which is indicated in fig. 3 by the line 20), the sewing material 9 is placed on the feed table 7 and is transferred to the material receiving device 10 by means of the feed table 7. The sewing material 9 may be a blank for a lady shirt, for example. In this starting position of the sewing device, the presser bar 18 and the presser foot 28 are located above and the feeder table 7 is extended. The sewing material 9 is held by means of the material receiving device 10 and the feed table 7 is moved back into its starting position by the drive movement of its drive. After the sewing material 9 is pressed against the platen by the presser bar 18, the sewing operation can be started. Here, the presser bar 18 is pressed against the table and the sewing material 9 by means of a pneumatic cylinder. The X-Y drive of plunger 18 positions this plunger to the "fabric stitch open end".

The free end 30a of the needle thread 30 is located above the counter-clamping element 27 of the plunger 18. When a seam has previously been produced on another sewing material under the needle plate, the free end 30a has been cut as close as possible to the needle hole by a further cutting element, not shown, which is arranged under the needle plate. The resulting needle thread end 30a should, however, project from the needle 29 with a certain length in order to ensure a reliable sewing of the seam to be produced.

As shown in fig. 4, the presser foot 28 is then moved downwardly. While the clamping device 25 is operated by means of the presser foot 28. The free end 30a of the upper thread 30 from the needle 29 is thereby clamped on the plunger 18 in the region of the thread start 30a between the clamping element 26 and the counter-clamping element 27. In this way, the yarn start 30a is carried along by the pressure rod 18 during its feed movement.

For clarity, presser foot 28 is not shown in fig. 5. As shown in the drawing, in the starting sewing operation, the presser bar 18 moves the sewing material 9 in the feeding direction, from right to left in fig. 5. After the first stitch is put in and the upper thread 30 is sewn on the sewing material, the cutting member 34 of the cutting device 33 is operated so that this cutting member is moved from the waiting position into the cutting position. This movement is carried out by a feed movement from the waiting position to the cutting position, which is substantially parallel to the Y direction and perpendicular to the X direction of the feed movement of the presser bar 18. The movement of the cutting element 34 from one end position to the other end position thereof takes place after the execution of at least the first stitch of the seam and stitch forming process and before the uninterrupted execution of the last stitch of the seam forming process.

In this case, the cutting element 34 is moved by its cutting edge 35 into the region between the clamping device 25 and the sewing material 9. In this case, by the continued feed movement of the sewing material 9, the tensioned end region of the upper thread 30 is guided to the blade edge and pressed against the cutting edge 35, which results in the upper thread 30 being cut off close to the first penetration point of the needle 29 and close to the presser foot 28. In this way, a short open end portion of the upper thread 30 left on the sewing material 9 is produced.

As shown in fig. 6, the cutting member is immediately moved back to its waiting position after the cutting of the needle thread 30. This retraction is performed automatically and is initiated by the controller of the sewing apparatus, for example, based on a particular number of stitches after the cutting member 34 has been moved into the cutting position. In the embodiment shown, the clamping device 25 remains closed during retraction of the cutting element 34, thereby continuing to hold the separated yarn ends during a subsequent sewing operation. Since the clamping device 25 is attached to the pressure lever 18, the clamping device 25 also performs a feed movement with the pressure lever 18. The clamping device 25 is thereby also moved past the suction device 37 during the feed movement. At the moment when the clamping device 25 reaches the height of the suction device 37, the controller initiates the opening of the clamping device 25 by deflection of the clamping element 26, and the suction device 37 sucks off the separated yarn remnants 30b, which were originally the free end 30a of the upper thread, by means of the suction air pulse. The sewing of the woven seam is finished. The sewing material 9 can then be extracted automatically or manually and the presser bar 18 is moved back into its starting position again in order to receive a new blank/sewing material 9. The sewing process can then be repeated in the same manner for a new blank/sewing material 9, either once or several times.

List of reference numerals

1 Sewing machine

2 working plate

3 Sewing machine

4 longitudinal edges

5 transverse edge

6 angle

7 feeding table

9 blank/Sewing Material

10 Material receiving device

11 feeding device

12 driver of material receiving device

14 angle square

14a horizontal side edge

16-needle row

18 pressure lever

19 direction of feed

20 weave direction of sewing

25 clamping device

26 clamping element

27 mating clamping elements

28 presser foot

29 needle

30 noodle

30a yarn opening

30b separated yarn residue

33 cutting device

34 cutting element

35 cutting edge

37 suction device

Claims

1. A sewing machine comprising at least one double-chain stitch sewing machine for producing at least one seam on a sewing material, in particular for producing at least one fold on a sewing material, wherein the sewing machine is equipped with a driven sewing material feed for a determined or determinable feed direction of the sewing material relative to a stitch forming tool, which feed direction is suitable for producing at least one seam on the respective sewing material, wherein the sewing material feed has a presser bar (18) by means of which the sewing material can be pressed against a table and moved past the stitch forming tool for producing the feed movement,

it is characterized in that the preparation method is characterized in that,

a clamping device (25) is provided on the pressure lever (18) and can be moved together with the pressure lever (18) in the feed movement thereof, wherein the clamping device (25) is suitable for clamping the thread start of the upper thread (30), and the sewing device has a cutting element (34) which is arranged at least temporarily in the region between the clamping device and the presser foot immediately after the start of a seam generating operation for cutting off the upper thread between the clamping device and the presser foot.

2. Sewing machine as in at least one of the preceding claims, characterized in that said clamping device (25) is equipped with a drive element and is operable independently of said presser bar (18).

3. Sewing machine as in at least one of the two preceding claims, characterized in that the clamping element (26) of the clamping device (25) is deflectable about a deflection axis in order to clamp the thread start of the upper thread (30).

4. Sewing machine as in claim 3, characterized in that said deflection axis is at least substantially parallel to the X feed direction of said presser bar (18).

5. Sewing machine as claimed in claim 3 or 4, characterized by a layout of said clamping elements (26), by means of which the clamping elements (16) fix the yarn on said presser bar, in particular on counter-clamping elements (27) of the presser bar (18).

6. Sewing machine as in at least one of the preceding claims, characterized in that the cutting element (34) is switchable to pass from a waiting position into a cutting position and from the cutting position into the waiting position.

7. Sewing machine as in at least one of the preceding claims, characterized in that said cutting element (34) is movable substantially transversely to the X-feed direction of said presser bar (18) so as to enter a cutting position.

8. Sewing machine as in at least one of the preceding claims, characterized in that said cutting element (34) is a single blade arranged at least temporarily in the feed path of the open end of the thread tensioned between said clamping device (25) and said sewing material (9).

9. A method for producing stitches on a sewing material (9) by means of a double-chain stitch sewing machine, wherein the sewing material (9) is fed into the sewing machine by means of a driven sewing material feed device in a defined or determinable feed direction of the sewing material (9) relative to a stitch forming tool, which feed direction is suitable for producing at least one seam on the respective sewing material (9), wherein the sewing material (9) is clamped to a table of the sewing machine by means of a pressure bar (18) and the at least one seam is introduced into the sewing material (9) for producing stitches such that the pressure bar (18) feeds the sewing material to the stitch forming tool of the double-chain stitch sewing machine in the feed direction, preferably in a changeable feed direction,

it is characterized in that the preparation method is characterized in that,

at the start time of the seam producing operation, the yarn start end of the upper thread (30) is clamped by a clamping device (25) connected with the press rod (18) and moving along with the press rod, and after the upper thread and the bottom thread are sewed on the sewing material, the cutting element (34) is located at the cutting position, thereby cutting the upper thread (30) between the clamping device (25) and the sewing material (9), and at the same time, the sewing operation is continuously carried out and continued.

10. Method according to claim 9, characterized in that after the start of the seam production operation and while the seam production operation is being carried out, the cutting element (34) is moved into a cutting position between the clamping device (25) and the sewing material in the feed path of the unstitched free yarn region, so that the unstitched yarn region is shortened by cutting.

11. Method according to at least one of the preceding claims 9 or 10, characterized in that the upper thread (30) passing through the needle is already clamped by the clamping device (25) before the stitch forming operation is started.

12. Method according to at least one of the preceding claims 9 to 11, characterized in that the press bar (18) is movable in an X-Y plane, wherein the X direction is the main direction of movement of the press bar during the production of the tuck and the cutting element (34) is brought into its cutting position by a movement substantially in the Y direction.

13. Method according to at least one of the preceding claims 9 to 12, characterized in that by means of a feed movement of the sewing material (9) a section of the upper thread (30) between the clamping device (25) and a presser foot (28) is guided to a cutting element (34) and is thereby cut off on the basis of the feed movement.

14. Method according to at least one of the preceding claims 9 to 13, characterized in that, for the purpose of producing a seam fold on the second sewing material, the upper thread (30) is cut off at the end of the sewing process previously producing a seam fold on the first sewing material, the second sewing material is removed from the sewing apparatus, the plunger (18) is moved back into its receiving position, and wherein the open clamping device (25) is arranged such that the free end of the upper thread is arranged in the clamping device, the clamping device (25) is closed, and the sewing process for the first sewing material is then started with the clamping device (25) continuing to be closed.