TW201900973A - Method for producing a seam end bottom thread with a pre-etermined target seam protrusion - Google Patents

Abstract

Prior to producing a seam end bottom thread with a target seam protrusion of at most 10 mm a lower feed plate (17) is repositioned from a sewing operation position into a cut-off position displaced relative to the sewing operation position along a sewing direction (x) prior to cutting off a bottom thread (35) at one end of a seam. The bottom thread (35) is then cut off at the end of the seam. A sewing machine for carrying out this method has a controller for controlling a displacement drive, which is designed in such a way that it controls the displacement drive for displacing the lower feed plate (17) from the sewing operation position into the cut-off position in a synchronised way at the end of a seam production. This results in a production method for a seam end bottom thread with a pre-determined target seam protrusion, where the seam end bottom thread, and therefore also the target seam protrusion, can be designed to be shorter.

Description

 Method for producing a bottom line of a seam end of a predetermined target seam projection and a sewing machine  

The invention claims the priority of the German patent application DE 10 2017 207 626.7, the disclosure of which is incorporated herein by reference.

The present invention relates to a method for producing a seam end line having a predetermined target seam projection. The invention further relates to a sewing machine for performing such a method.

A sewing machine is known from EP 1 847 641 B1 and EP 2 330 241 B1, with which a seam end line having a predetermined target seam projection can be produced.

It is an object of the present invention to develop a method for producing a seam end bottom line having a predetermined target seam projection such that the seam end bottom line and thus the target seam projection can be designed to be shorter.

According to the invention, this object is achieved by a method for producing a seam end line having a target seam projection of at most 10 mm by the following steps: a suture seam; a lower portion of the seam before the end of the thread is cut The feed plate is repositioned from the stitching operation position to a cutting position that is displaced in the stitching direction relative to the stitching operation position; and the bottom end of the wire seam is cut.

It has been found in accordance with the present invention that the position of the lower feed plate can be displaced after the seam is formed and before the end of the wire is cut, so that the bottom line path between the last stitch of the seam and the cut position can be shortened. This results in a corresponding shortening of the bottom line of the seam end. Since the position of the lower feed plate at the cutting position can be clearly defined, such shortening can be accurately reproduced to produce a predetermined target seam projection according to the position of the lower feed plate. While the bottom line of the seam end having the target seam projection is produced, it is also possible to produce a seam end upper line having a similar target seam projection of, for example, no more than 10 mm. With this generation method, the upper line can be cut off simultaneously with the bottom line. Then, repositioning the lower feed plate from the sewing operation position to the cutting position can shorten the upper line path between the last stitch of the seam and the cutting position before cutting the upper thread, which leads to a corresponding shortening of the upper end of the seam end. . Thus, depending on the position of the lower feed plate, a corresponding predeterminable target seam projection on the upper end of the seam is produced. The lower feed plate is correspondingly repositioned to the cutting position, at which time the bottom line path and/or the upper line path between the last stitch of the seam and the cut position are extended, so that an extension having, for example, significantly more than 10 mm can also be produced. The bottom line of the seam end of the target seam projection and/or the end of the seam end. This can be significant for certain stitching tasks that require longer seam ends. The lower feed plate can be a feed dog or a cloth pusher. The lower feed plate can be synchronized with the stitch forming tool of the sewing machine (i.e., the sewing needle and the gripper) and/or can be operated periodically. The lower feed plate indicates a member that conveys the sewn fabric in the sewing direction from below by frictional contact. Here, the lower feed plate engages the sewn cloth during sewing during the first period of time and does not engage the sewn cloth during another period of time.

A stitch having a shortened stitch length before the cutting during the stitching means that the bottom line of the seam end produced by the cutting and the line at the end of the seam are relatively long from the sewing cloth to the cutting position, and thus The last shorter stitches, they actually have the same length.

Repositioning the lower feed plate before it is displaced in the stitching direction can result in a beneficial reduction in the bottom line path between the last stitch and the cut position depending on the design of the sewing machine. The "return needle" position can be selected as the cutting position of the lower feed plate.

The repositioning of the lower feed plate can be combined with the normal operation of the sewing machine, and the repositioning of the lower feed plate is accomplished by an adjustment device that controls the conveyance length of the feed plate drive for the lower feed plate. Then, additional repositioning drivers can be omitted.

Another object of the invention is to provide a sewing machine for carrying out the method according to the invention.

According to the invention, this object is achieved by a sewing machine for carrying out the method according to the invention, the sewing machine comprising: a stitch forming tool for stitching seams with upper and lower threads; a lower feed that is displaceable along the stitching direction a wire cutter for cutting the bottom thread at the end of the thread; a driver for shifting the lower feed plate along the stitching direction; a controller for controlling the shifting drive, wherein the controller is designed such that it is online At the end of the seam generation, the shift actuator is controlled in a synchronized manner such that the lower feed plate is displaced from the stitching operation position to the cut position.

The advantages of the sewing machine are the same as those already described above with reference to the method according to the invention. The actuator for displacing the lower feed plate can constitute an adjustment device for the feed plate drive.

The controller for controlling the shifting drive can be designed to program the length of the excess bottom line of the set of end portions of the wire. The length of the excess bottom thread can be pre-selected by the operating elements on the sewing machine.

A stitch setting transmission mechanism for setting the transport length of the lower feed plate is particularly suitable as a displacement drive for repositioning the lower feed plate from the sewing operation position to the cut position. In particular, the stitch setting transmission mechanism can be designed as a tab gear. Such a suitable stitch setting transmission mechanism is known from EP 2 330 241 B1.

The rotary drive of the shifting drive for the stitch setting mechanism of the stitch setting drive constitutes a particularly simple drive for repositioning the lower feed plate from the stitching operating position to the cut position. The rotary drive can be designed as a stepper motor. Alternatively, the rotary drive can be designed as a linear solenoid or a pneumatic cylinder. The rotary drive can cooperate with the at least one stop to set the at least one lower feed plate position. The stop can be adjustable. Several such stops are also contemplated.

1‧‧‧ sewing machine

2‧‧‧Substrate

3‧‧‧ bracket

4‧‧‧ Arm

5‧‧‧ nose

6‧‧‧Bear axis

7‧‧‧Crank Drive

8‧‧‧Wire rod

9‧‧‧ Needle bar

10‧‧‧ needle

11‧‧‧ axis

12‧‧‧ spool

13, 35‧‧ ‧ line

14‧‧‧Support board

15‧‧‧cloth section

16‧‧‧ recess

17‧‧‧Feeding tooth/fabric pusher/lower feed plate

17a‧‧‧Foot press

18‧‧‧ stitch holes

18a‧‧‧Shift drive

18b‧‧‧ Controller

19‧‧‧Clamping device

20‧‧‧Clamping body

21‧‧‧Clamp tip

22‧‧‧ pot-shaped spool housing

23‧‧‧Clamping axis

24‧‧‧Operation direction of rotation

25‧‧‧Axis

26‧‧‧ bearing housing

27‧‧‧Drive shaft

28‧‧‧Belt drive

29‧‧‧Wire cutter

30‧‧‧Rotation axis

32‧‧‧ bottom edge of the groove

31‧‧‧ wire trough

32, 34‧‧‧ edge

32a‧‧‧ base

32b‧‧‧Edge section

32c‧‧‧Free end section

33‧‧‧ opposed blade

34‧‧‧ opposed blade edge

36‧‧‧Feeding plate support

37‧‧‧Feeding plate shaft

38‧‧‧Feeding plate lifting shaft

39‧‧‧Feeding plate section

40‧‧‧ stitching

41‧‧‧Kitchel end line

S ₁ to S ₅ ‧‧‧ stitches

x, y, z‧‧ direction

Embodiments of the present invention will now be described with reference to the drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view of a two-wire chain stitch sewing machine; FIG. 2 is a plan view of a portion of the sewing machine shown in an enlarged scale corresponding to the arrow II in FIG. 1; Figure 3 is a front elevational view of the internal details of a portion of the sewing machine, shown in an enlarged scale, in Figure 3; Figure 4 is a perspective view of the wire cutter; Figure 5 is along the line VV of Figure 1 A cross-sectional view of the current position of the lower feed plate and the wire cutter when the bottom line cut at one end of the wire seam according to the prior art is used to produce the bottom end of the seam end with the target seam projection; Figure 6 is similar to Figure Figure 5 is a schematic view showing the current position of the lower feed plate and the wire cutter when the bottom end of the wire is cut to produce a bottom end of the seam end of the target seam projection of no more than 10 mm; 7 is a schematic plan view of a seam sewn by a sewing machine for explaining the generated bottom line of the seam end having the set target seam projection.

The sewing machine 1 (particularly designed as a two-wire chain stitch sewing machine) has a base plate 2, and has a bracket 3 extending upward from the base plate 2 and an angled arm 4. The angled arm 4 terminates in the handpiece 5. The arm shaft 6 is rotatably mounted in the arm 4. This drives the crank drive 7 through the wire rod 8 in the handpiece 5. The crank drive 7 is drivingly coupled to a needle bar 9 that is axially displaceably mounted in the handpiece 5. There is a needle 10 at the lower end of the needle bar 9. The needle 10 can be moved up and down on the vertical axis 11 by the crank drive 7. The needle 10 holds the needle thread 13 supplied through the bobbin 12 in the eye of the needle via a wire pretensioning device and a wire rod 8, which is also referred to as an upper thread.

The substrate 2 carries a support plate 14 fixed by screws, and the double-layer sewn cloth portion 15 is placed on the support plate 14. The support plate 14 is designed to have a recess 16 for passing through a feed dog or cloth pusher 17 (also referred to as a lower feed plate). The latter has a stitch hole 18 for passing through the needle 10.

The cloth pusher 17 is disposed opposite the presser foot 17a with respect to the sewing fabric portion 15.

The Cartesian xyz coordinate system is used to illustrate the subsequent positional relationship. The direction x extending along the stitching direction extends perpendicular to the drawing plane in Figure 1 and extends into the drawing plane. In Figure 1, the direction y extends to the left. In Figure 1, the axis 11 extends upwardly in the direction z in which it extends. During the stitching process, the cloth pusher or the lower feed plate 17 conveys the sewn fabric portion 15 in the positive x direction along the stitching direction.

The cloth pusher 17 is drivingly coupled to a propulsion and lift drive mechanism disposed below the base plate 2. Such a transmission for the lower feed plate 17 can be designed as a stitch setting transmission and is in particular set as a claw transmission as described in EP 2 330 241 B1. This stitch setting transmission mechanism constitutes a feed plate transmission mechanism, and in particular, the wire length setting transmission mechanism can adjust the conveyance length of the lower feed plate 17, that is, the stitch length during the occurrence of the seam. The stitch setting transmission mechanism is a part of a driver for displacing the lower feed plate 17 in the sewing direction x. In Figure 1, the shifting drive is shown schematically at 18a. The shift drive 18a cooperates with the central controller 18b shown schematically in Figure 1, much like the other driven components of the sewing machine 1. To this end, the controller 18b is directly connected to these components of the sewing machine 1 to be controlled, in particular in a manner not illustrated here, in particular to the shifting drive 18a. The rotary drive for the stitch setting axis of the stitch setting transmission is part of the shift drive 18a. In particular, such a stitch setting axis is described in connection with Fig. 2 of EP 2 330 241 B1, which is hereby incorporated by reference. According to the rotation angle of the stitch setting shaft, the stitch length and the relative position of the lower feed plate 17 in the x direction with respect to the member of the sewing machine 1 connected to the substrate are obtained. Therefore, the rotary actuator is an adjustment device for the transport length of the lower feed plate 17 of the stitch setting transmission mechanism.

A gripper 19 having a gripper body 20 is located below the support plate 14, which has a gripper tip 21. A pot-shaped bobbin case 22 for receiving the gripper line storage is housed in the gripper body 20. The gripper line is also described below as the bottom line.

The gripper 19 is rotatable about a vertical gripper axis 23. The stitching operation rotational direction 24 extends in a clockwise direction about a gripper axis 23 extending in the direction z in FIG. The gripper body 20 is permanently connected to the shaft 25, which extends coaxially with the gripper axis 23. The shaft 25 is rotatably mounted in a bearing housing 26 that is screwed onto the base plate 2. A drive shaft 27 coupled to the transmission drive is disposed within the bearing housing 26. The transmission drive has a gear ratio of 1:2 such that one rotation of the drive shaft 27 causes the gripper body 20 on the shaft 25 to rotate twice. The drive shaft 27 is drivably coupled to the arm shaft 6 via a belt drive 28.

The wire cutter 29 is used to cut the wire gripper. The wire cutter 29 is rotatable about a rotational axis 30 parallel to the gripper axis 23 at the basic position and the take-up position shown in FIG. In the view according to Fig. 2, the wire cutter 29 has a basic shape reminiscent of a file, the free end of which runs in a basic position around the bobbin housing 22 in the view according to Fig. 2. At the take-up position of the wire cutter 29, the take-up groove 31 (see Fig. 4) of the wire cutter 29 having the groove bottom side edge 32 is located near the stitch hole 18. The take-up groove 31 is designed in the angled edge portion 32b of the wire cutter 29, which is arranged at a right angle to oppose the horizontally extending base 32a. The extended free end portion 32c of the wire cutter 29 is designed to have the end of the circle shown in the top view of FIG.

The fixed-point opposed blade 33 (see FIG. 3) is fixed to the cantilever on the substrate 2, and when the wire cutter 29 is rotated from the take-up position to the basic position, the opposing blade 33 is cut and the wire cutter 29 is cut. The edges 32 cooperate to cut the line.

The opposing blade edge 34 of the opposing blade 33 of the cutting wire, which cooperates with the edge 32 of the wire cutter 29, extends vertically in the direction z.

Figures 5 and 6 respectively show the current position of the components of the sewing machine 1, first the "short forward stitch" position (Figure 5), and secondly the "return needle" position (Figure 6). The cutting position is shown according to the current positions of Figures 5 and 6, i.e., the upper line 13 and the lower line between the edge 32 of the cutting wire cutter 29 and the opposing blade edge 34 of the opposing blade 33, respectively. The current location described at the time before 35. Firstly further it shows the last line 15 to be sewn _{stitch. 1} to S ₅ S on line 13 during the path, and secondly it behind the path 35 shown. The lower feed plate 17 is also shown by a dashed line in the area of the stitch hole 18 so that the portion located behind the wire cutter 29 and the opposing blade 33 can be seen. Figures 5 and 6 also show details of the moving guide of the lower feed plate 17 having the lower feed plate support 36, the lower feed plate shaft 37 and the lower feed plate lift shaft 38; extending in the direction x via the moving guide The transfer hub is transferred to the lower feed plate 17; the immersion or draw-out lifter acting in the direction z is applied to the lower feed plate 17 by means of the lower feed plate lift shaft 38. The shift driver 18a is not shown in Figs. 5 and 6, and the shift driver 18a acts on the stitch setting axis not shown in Figs. 5 and 6.

Figure 5 shows the current position of the normal operation of the sewing machine 1 with which a short seam end line is created. Before forming a fifth stitch S _5, by shift actuator 18a to set the stitch actuator to reposition "the front short track" position, such that the last stitch previously generated S ₅ S ₁ to trace S _{4 is} short. Once it has been fasten a fifth stitch S _5, the bottom lines 13 and 35 to travel to a position between the cutting edge 32 and 34 opposite the blade edge. In particular, the bottom line 35 is routed around a portion 39 of the lower feed plate 17 along a slightly U-shaped path therein, the portion 39 of the lower feed plate 17 defining a stitch hole 18.

Figure 6 shows the same in the formation of the corresponding track member is designed as a short stitch line sewing line S 1 after _five trace set gear position "back needle" in. In this position of the track setting drive mechanism, repositioning is performed by corresponding control of the shift drive 18a.

Due to the "return" position, the feed plate shaft 37 of Figure 5 is rotated more counterclockwise than Figure 6, such that the lower feed plate is in the current position of Figure 6 as compared to the current position according to Figure 5. 17 is displaced in the positive x direction (ie, the stitching direction). This causes the feed plate portion 39 to be displaced relative to the cutting positions of the wires 13, 35, independent of the stitch setting transmission, and in principle also cuts the edge 32 and the opposite in the same positive x direction as in Fig. 6. The upper line 13 and the lower line 35 between the blade edges 34 are previously frame-fixed. The feed plate portion 39 moves relative to the sewing fabric portion 15 when repositioned to the "return needle" position. At the same time, the sewing fabric portion 15 is fixed relative to its holding position by the presser foot 17a. The path between the last stitch S ₅ and the cut-off position between the edges 32, 34 is now more than just for the lines 13, 35, since it is in the current position according to Figure 5, in particular for the current position according to Figure 6. The bottom line 35 is such that after the cutting lines 13, 35, a smaller seam end line is produced on the sewn cloth portion 15, and in particular a shorter seam with a target seam projection of no more than 10 mm End line.

FIG. 7 shows the seam 40 produced by the sewing machine 1. Seam bottom end portion 41 from the last stitch S ₅ to protrude, wherein the target projecting seam portion A with respect to the seam 40 does not exceed 10mm.

A method for producing such a seam end bottom line having a target seam projection of no more than 10 mm includes stitching a seam with a stitch Si, wherein the lower feed plate 17 is before the end of the stitch is cut by the end of the stitch. Displacement from the stitching operation position (eg, from a "short forward stitch" position) to a cut position (ie, such as a "back stitch" position) that is displaced along the stitching direction x. Then, the bottom wire 35 and the upper thread 13 are cut by the wire slit end 29 by the engagement between the edges 32, 34.

The lower feed plate 17 can also be displaced to another cutting position, which is displaced in the negative x direction, as compared to the cutting position according to Fig. 5, such that the path of the bottom line 35 first faces between the edges 32, 24. The cut position extends, and the path of the upper line 13 further extends toward the cut position between the edges 32, 24. In this position of the lower feed plate 17, this may be the "maximum forward stitch length" position. Correspondingly extending seam end lines 13, 35 are produced.

Here, the stitch shortening (for example, the stitch shortening of the last stitch S ₅ ) is not necessary. Thus, the stitching can also continue with the normal stitch length until the last stitch, wherein the repositioning of the stitch setting drive from the "normal forward stitch" position to the subsequent cutting position of the lower feed plate 17 is then achieved. That is, for example, repositioning to the "return" position.

The controller 18b is designed such that its shift actuator 18a is controlled in a synchronized manner at the end of the line seam generation, i.e., the lower feed plate 17 is displaced from the stitching operation position to the cut position. Here, the controller 18b is designed to be programmable for setting the excess bottom line length at the end of the seam.

The shift driver 18a is designed as a stepping motor. Alternatively, the shift drive can be designed as a linear solenoid or pneumatic cylinder. When a linear solenoid or pneumatic cylinder is activated, at least one stop can be envisaged here for setting the position of the stitch setting transmission. This stop can be an adjustable design. It is also conceivable to have more than one stop.

Claims (7)

 A method for producing a seam end bottom line having a target seam projection of up to 10 mm using the following steps: - a suture seam; - feeding the lower portion before cutting the bottom thread at one end of the seam The plate is repositioned from the stitching operation position to a cutting position that is displaced in the stitching direction relative to the stitching operation position; - the bottom line is cut at the end of the seam.    The method of claim 1, characterized in that the stitch having the shortened stitch length is realized before the cutting during the stitching.    The method of claim 1, wherein the lower feed plate is displaced in the stitching direction when the lower feed plate is repositioned.    The method of claim 1 wherein the repositioning of the lower feed plate is accomplished by an adjustment device for controlling the transport length of the lower feed plate of the feed plate drive.    A sewing machine for performing the method according to claim 1, characterized in that - a stitch forming tool having a suture seam using upper and lower threads, - a lower feed plate that is displaceable in the stitching direction, - having a wire cutter for cutting a bottom thread at a seam end, having a driver for displacing the lower feed plate in a stitching direction, - having a controller for controlling the shift driver, wherein The controller is designed such that it controls the shifting drive in a synchronized manner at the end of the spool creation such that the lower feed plate is displaced from the stitching operating position to the severed position.    A sewing machine according to claim 5, characterized by comprising a stitch setting transmission mechanism for setting a conveyance length of said lower feed plate.    A sewing machine according to claim 6, wherein the shifting driver has a rotary actuator for a stitch setting shaft of the stitch setting transmission mechanism.