TWI788349B - Assembly for producing a starting top thread of a seam with a target seam protrusion and sewing machine comprising the same - Google Patents

Abstract

An assembly (40) serves for producing a starting top thread of a seam with a target seam protrusion of at most 10 mm. The assembly (40) has a top thread catcher (41) for taking up the starting top thread of the seam. The top thread catcher (41) has a top thread blade (42) with a top thread take-up section. The top thread catcher (41) further has a counterblade (44) and a top thread clamp (45) as well as a displacement drive (48) for the top thread take-up section. The latter can be displaced with the displacement drive (48) between a top thread take-up position, a top thread clamping position and a top thread cutting position. The result is a reproducible desired short target seam protrusion and a safe attachment.

Description

Assembly for producing a seam start top thread with a target seam projection and sewing machine comprising the assembly

The content of German patent application DE 10 2017 207 627.5 is hereby incorporated by reference.

The invention relates to an assembly for producing a seam starting top thread with a target seam overhang of at most 10 mm. The invention also relates to a sewing machine with such an assembly.

Sewing machines are known from EP 1 847 641 B1, DE 102 34 251 C1, DE 10 2006 019 193 A1 and DE 101 23 075 C1. DE 10 2015 223 194 B3 describes a method for producing a seam starting top thread with a short target seam overhang and an assembly for implementing the method. DE 34 34 40 874 A1 discloses a thread cutting device for sewing machines. US 6 062 152 A discloses an automatic thread cutting device for embroidery machines. DE 38 12 092 C2 discloses a button sewing machine with a thread separating and clamping device. DE 100 63 003 B4 describes a thread cutter for sewing machines. DE 197 19 847 A1 describes a thread cutting device for a sewing machine. DE 10 2006 059 192 A1 discloses a sewing machine line separator. DE 298 11 472 U1 discloses a thread cutting device for a sewing machine for chain sewing tasks. DE 10 2007 056 132 A1 discloses a sewing machine with a thread cutting mechanism. DE 100 55 258 C1 discloses a thread cutter for use in sewing machines with a rotary gripper.

It is an object of the present invention to further develop an assembly of the above-mentioned type such that a reproducible desired short target seam protrusion is achieved. At the same time, secure attachment is guaranteed at the start of seam production.

This object is solved according to the invention by an assembly for producing a seam-starting top thread with a target seam projection of at most 10 mm, which assembly comprises a top-thread catcher for provoking the seam-starting top thread, Wherein the top thread catcher has a top thread blade with a top thread raising part, a butt blade, a top thread clamp, a shift drive for the top thread raising part, wherein the top thread raising part can be used with a shift drive Top thread pick-up position for seam start top thread, top thread clamping position between top thread blade and top thread clamp for seam start top thread and between top thread blade and counter blade Shift between the top thread cutting positions for the top thread at the start of the cut seam.

According to the present invention, it has been found that the top thread or upper thread pick-up portion of the top thread blade can be used both to clamp the seam start top thread and also to cut the seam start top thread in order to produce a defined seam. Short starting top line. Thus, a compact assembly is possible that ensures clamping on the one hand and cutting of the starting top line on the other hand. Butt blades can simultaneously form a top wire clamp. Alternatively, the top wire clip can be designed as a separate component from the butt blade. The butt blade may be arranged to be fixed to the frame. Alternatively, the butt blade may move relative to the frame of the sewing machine during cutting. The top thread raising position, the top thread clamping position and the top thread cutting position are the top thread raising part relative to each other different locations. The top thread clamping position may be a position where the top thread raising portion is located between the top thread raising position and the top thread cutting position.

The shift drive is designed to be cost effective with exactly one drive that shifts the top wire lifter between the three positions.

The displacement drive is designed to be precise as a linear drive, where a linear guide guides the displacement movement of the top wire provocation between three positions.

The displacement drive can be designed as a lifting cylinder, in particular as a pneumatic lifting cylinder. Alternatively, the shift drive can be designed as a stepper motor. The stepper motor can be controlled with a corresponding controller in such a way that the three positions of the top wire raising portion are equal to the corresponding step positions of the stepper motor. With this design of the stepper motor, stops for defined positions can be omitted.

An adjustable clamping position stop for specifying the relative position of the top thread blade and the top thread clamp in the top thread clamping position simplifies the production of the assembly.

Clamping position stops with self-restraining threaded pins are cost-effective for production. Self-damping is achieved by screwing threaded pins into a plastic body secured to the frame.

An adjustable cutting position stop for specifying the relative position of the topline blade and the abutment blade in the topline cutting position simplifies production of the assembly.

The stop body of the cutting position stopper can be displaced transversely to the cutting motion direction of the top line blade to specify the relative position of the top line blade and the butt blade, and can realize precise adjustment of the cutting position stopper, wherein the cutting position stopper The force absorbed by the element does not act in the displacement direction of the locking body, which can lead to an undesired sliding of the locking element.

Suction device for suctioning off the severed top line section avoids the top line Undefined deposition of parts. This avoids undesired accumulation of cut thread remnants in the area of the sewing machine.

The advantages of the sewing machine with the assembly according to the invention are equal to those already described above with reference to the assembly according to the invention, the sewing machine having a driven needle bar with a needle for guiding the top thread carried by it. A sewing needle, the sewing machine also has a gripper for picking up the top thread forming the stitch.

1:Sewing machine

2: Platen

3: Bracket

4: arm

5: head

6: Arm shaft

7: crank mechanism

8: wire rod

9: needle bar

10: Needle

11: axis

12: Spool

13: needle thread; top thread

13a: Beginning of the top line

14: Contact plate

15: Sewing workpiece

17:Material pusher

18: pinhole

19: Gripper

20: Gripper body

21: Gripper tip

22: Spool housing

22a: Spool

23: Gripper axis

24: Rotation direction

25: axis

26: bearing seat

27: drive shaft

28: Belt drive

29:Pull wire blade

30: presser foot

31: Transporter

32: Line tensioning device

33:Top thread guide clip

34:Tension disc

35: guide rod

36: Pressure spring

37: Support

38: Electromagnet

39: Central controller

40:Sewing machine components

41: Top Line Catcher

42: Topline Blade

43: Top line provocation part

44: Butt blade

45: top wire clip; clamping spring

46, 47: screw

48: shift drive; lifting cylinder

49: Guide pin

50:piston

51: piston rod

52: Slender hole

53: Mounting plate

54: threaded pin

55: Plastic body

56: Through hole

57: Driver support plate

58: Clamp stop driver

59: Piston rod

60: stop body; stop plate

61: inclined wall part

62: Adjusting screw

63: Slender hole

64: Suction device

65: suction pipe

65a: cut off area

66: Opposite end

67: seam

A: seam protrusion

S ₁ -S _u : Stitch

Embodiments of the present invention will be explained in more detail below with reference to the accompanying drawings. The accompanying drawings show: Fig. 1 is a front view of a double-sided backstitching sewing machine; Fig. 2 is a perspective view of a stitch forming area of a sewing machine; Fig. 3 is a perspective view of a bedplate of a sewing machine, with some parts removed so The assembly for producing a seam-starting top thread with a defined target seam protrusion is visible; FIG. Part of the top thread blade or face thread blade is shown in the fully extended top thread raised position; Fig. 5 is the assembly according to Fig. 4 seen from above; Fig. 6 is the assembly according to Fig. 4 seen obliquely from above Fig. 7 is the assembly according to Fig. 4 when the top wire lifting part is in the retracted top wire clamping position; Fig. 8 is the assembly viewed from the viewing direction VIII in Fig. 7; Fig. 9 is a view similar to Fig. 5 The illustrated components are in the position of Figure 7; Figure 10 is similar to the position of the components illustrated in Figure 6 in Figure 7; Figure 11 is an oblique perspective view from below of the assembly shown in Figure 7; Figure 12 is a top-line cutting position of the assembly similar to that shown in Figure 4 with the top-line lifting portion more retracted relative to the top-line clamping position ; Fig. 13 is a partial sectional view according to the line XIII-XIII in Fig. 12; Fig. 14 is a position similar to that shown in Fig. 5 in the position of Fig. 12; position; and FIG. 16 is a schematic top view of a seam sewn with the sewing machine according to FIG. 1 for illustrating the initial top thread produced by the seam with a defined target seam protrusion.

A sewing machine 1, which is particularly designed as a double-sided reverse stitch sewing machine, has a table 2 with an angled arm 4 with a bracket 3 extending upwardly therefrom. The angled arms end with a head 5 . An arm shaft 6 is rotatably installed in the arm 4 . The arm shaft drives the crank mechanism 7 via a wire rod 8 in the head 5 . The crank mechanism 7 is connected to be driven by a needle bar 9 arranged axially displaceably in the head 5 . The needle bar has a needle 10 at its lower end. The needle 10 can be moved up and down on a vertical axis 11 by means of a crank mechanism 7 .

In order to simplify the illustration of the positional relationship, we will use the Cartesian xyz coordinate system in the following. The vertical axis 11 extends in the z-direction of this coordinate system. The direction x extends perpendicularly into the drawing plane of FIG. 1 and parallel to the sewing direction of the sewing machine 1 . The direction y extends to the left in FIG. 1 .

The needle 10 brings the needle thread 13 fed from the bobbin 12 through the thread tensioning device and the thread rod 8 into the eye of the needle. Needle thread 13 is also described as top thread or upper thread. The needle thread 13 has a free top thread start 13a.

The table 2 has a screw-mounted contact plate 14 on which a sewing workpiece 15 rests. The contact plate 14 is equipped with a pusher 17 for the lower material to be worn past recesses. The lower material pusher has a needle hole 18 through which the needle 10 passes. The material pusher 17 is connected to a pusher lift gear arranged below the table 2 and is driven in a known manner.

The gripper 19 is located below the contact plate 14 and has a gripper body 20 with a gripper tip 21 . Mounted in the gripper body 20 is a pot-shaped spool housing 22 for receiving a gripped line reservoir in the form of a spool 22a. The contours of the upper edges of the spool housing 22 on the one hand and the spool 22a on the other hand are indicated by dashed lines in the schematic diagram of FIG. 2 . This clamping line is also referred to as a bottom line.

The gripper 19 is rotatable about a vertical gripper axis 23 extending in the z-direction. The sewing operation rotational direction 24 of the gripper body 20 extends clockwise about the gripper axis 23 in FIG. 3 . The gripper body 20 is permanently connected to a shaft 25 extending coaxially with the gripper axis 23 . The shaft 25 is rotatably mounted in a bearing seat 26 screwed to the table 2 . A drive shaft 27 connected to a gear transmission arranged inside the bearing housing 26 is mounted in this bearing housing. The gear transmission has a gear ratio of 1:2 so that one rotation of the drive shaft 27 rotates the gripper body 20 on the shaft 25 twice. The drive shaft 27 is connected to be driven by the arm shaft 6 through a belt drive 28 .

A thread-drawing blade 29 (see FIG. 3 ) is used to cut the needle thread 13 and the clamping thread at the end of the seam and is known, for example, from EP 1 847 641 B1.

The sewing machine 1 also has a presser foot 30 for holding and conveying the sewing workpiece 15 and an upper carrier 31 cooperating with the lower material pusher 17 to convey the sewing workpiece.

The schematic diagram 2 additionally shows the path of the top thread 13 from the spool 12 to the top thread pick-up portion 13a. Starting from the bobbin 12 , the top thread 13 is guided to the needle 10 via the thread tensioner 32 and the thread rod 8 and the top thread guide clip 33 .

The top thread guide clip 33 has a tension disc 34 mounted on a guide rod 35 . The tensioning disk 34 is pulled against the housing mount 37 of the top wire guide clip 33 by means of a compression spring 36 for clamping the top wire 13 . The electromagnet 38 shown schematically in FIG. 2 is mounted on a support 37 and can be controlled by a central controller 39 of the sewing machine 1 in a manner not shown in detail here.

An embodiment of a sewing machine assembly 40 for producing a seam-starting thread with a target seam overhang of at most 10 mm is described below with reference to FIGS. 3 to 15 .

With respect to the xz level on which the axis of movement 11 of the sewing needle 10 lies, the assembly 40 is arranged on the opposite side of the xz level to the gripper 19 (see FIGS. 1 and 3 ).

The assembly 40 has a top thread catcher 41 for picking up the seam starting top thread at the beginning of the seam to be sewn with the needle thread 13 . The top thread catcher 41 has a top thread blade 42 (see eg FIG. 5 ) with a top thread pick-up portion 43 designed as a through channel. The top thread catcher 41 also has an abutment blade 44 which cooperates with the top thread blade 42 to cut the needle thread 13 . The butt blade 44 is permanently mounted on the frame of the sewing machine 1 .

The top thread catcher 41 also has a top thread gripper 45 . The top wire clamp 45 is designed as a U-shaped clamping spring. The contact pressure of the clamp spring 45 against the top thread blade 42 can be adjusted by a clamp spring adjustment screw 46 . Blade pressure, ie the contact pressure of the butt blade 44 against the topline blade 42 , can be adjusted by the blade adjustment screw 47 .

The top thread blade 42 can be displaced by a shift driver 48 together with the top thread pick-up portion 43 . The displacement drive 48 is designed as a pneumatic lifting cylinder. The displacement movement of the top wire provocation portion 43 extends in the direction y and thus extends linearly. The top thread raising part 43 can be displaced between three positions by means of a displacement drive 48, namely between the following three positions: - a top thread raising position for raising the seam start top thread, - a top thread clamping position for clamping the seam start top thread between the top thread blade 42 and the top thread clamp 45, and - Top thread cutting position for cutting seam starting top thread between top thread blade 42 and butt blade 44 .

The position of the top line provocation is shown in Figure 4 to Figure 6. The top line clamping position is shown in Figure 7 to Figure 11. Top wire cutting locations are shown in Figures 12 to 15.

The top thread raising position, the top thread clamping position, and the top thread cutting position are positions of the top thread raising portion 43 that are different from each other. These three positions can be specified by shifting the actuator 48, ie with only one actuator.

A linear guide guides the displacement movement of the top thread pick-up portion 43 between the three positions. The linear guide comprises a guide pin 49 which extends approximately in the direction z and is mounted on a connecting piston 50 which is connected with high tensile strength to the piston rod 51 of the lifting cylinder 48 . The guide pin 49 cooperates with an elongated hole 52 in the mounting plate 53 of the assembly 40 for guiding the displacement movement of the top wire pick-up portion 43 (see eg FIGS. 4 and 5 ). The top thread blade 42 is mounted to the guide pin 49 at the end opposite to the mounting plate 53 .

In the top-line pick-up position, the top-line blade 42 extends in the negative y-direction farther than the abutment blade 44 so that the top-line pick-up portion 43 fully protrudes from the top-line blade 42 and the top-line clamp 45 and is freely accessible. For needle 10 to pass through.

The adjustable clamping position stop is used to define the relative position of the top thread blade 42 and the top thread clamp 45 in the top thread clamping position. The clamped position stop comprises a threaded pin 54 screwed into a plastic body 55 . This achieves self-damping of threaded pin 54 . In the stop position of the clamping position stopper, i.e. in the clamping position of the top line according to Figures 7 to 11, the screw The free end of the thread pin 54 hits the guide pin 49 and thus limits the movement of the top thread blade 42 in the positive y direction from the top thread raised position, ie eg to the left in FIG. 7 . In order to adjust the precise position of the top-thread lifting portion 43 in the top-thread clamping position, the threaded pin 54 is correspondingly turned relative to the plastic body 55 . To this end, the threaded pin 54 is accessible from the outside through a through hole 56 in the driver support plate 57 (see FIG. 8 ).

The clamped position stop is displaceable between a stop position shown in particular in FIG. 7 and an inactive intermediate position. This intermediate position is shown, for example, in FIG. 12 . A clamping stop drive 58 is used for displacing the threaded pin 54 of the clamping position stop, which is also designed as a pneumatic lifting cylinder. The plastic body 55 is connected to a clamping stop drive 58 via a clamping stop drive piston rod 59 .

In the stop position of the clamped position stop, the plastic body 55 supports itself on the driver support plate 57 against the pretension exerted by the guide pin 49 on the threaded pin 54 (see FIG. 7 ).

A pinch stop driver 58 is also mounted on the driver support plate 57 . The driver support plate 57 is arcuate in an L-shape, with the top line lifter shift driver 48 mounted on the first leg of this L and the pinch stop driver 58 mounted on the second leg. The displacement movement via the clamping stop drive 58 is effected approximately perpendicular to the displacement movement via the displacement drive 48 .

In the top thread clamping position, the top thread is clamped between the top thread clamp 45 and the top thread blade 42 . This clamped position is such that the cutting edge of the top thread blade 42 has not yet cooperated with the counter blade to sever the top thread 13 .

The assembly 40 also has adjustable cutting position stops for specifying the relative position of the topline blade 42 and the abutment blade 44 in the topline cutting position. The cutting position stop has a stop body 60 formed by a stop plate (see FIGS. 12 and 13 ). stop plate In turn the cutting stop position of the cutting position stop cooperates with the guide pin 49 of the assembly 40 . The contact between the guide pin 49 and the stop plate 60 is realized in the region of the inclined wall part 61 of the stop plate 60 , that is to say in the region of the edge part, which is related to the x-axis or the seam in the top view according to FIG. 13 . direction at an angle.

The relative position of the stop plate 60 to the mounting plate 53 can be defined by a mounting connection with an adjusting screw 62 extending through an elongated hole 63 extending in the direction x in the stop plate 60 (see FIG. 13 ). , for adjusting the cutting position stop. To adjust the cutting position stop, the stop plate 60 is displaced in direction x after corresponding loosening of the adjusting screw 62 , so that the contact area between guide pin 49 and inclined wall portion 61 is displaced in direction y in the cutting stop position.

The stopper 60 is displaceable transversely to the cutting movement direction of the topline blade 42 (ie, transverse to the direction y) to define the relative position of the topline blade 42 and the counter blade 44 .

In the stop position of the cutting position stop (see FIG. 13 ), the stop plate 60 supports itself against the pretension via the guide pin 49 on the driver support plate 57 .

When the clamping position stopper is in the middle position, the cutting position stopper operates.

The assembly 40 also has a suction device 64 for sucking a portion of the top thread 13 severed by the top thread blade 42 . The suction device 64 has a suction tube 65 with a suction end opening below the cut-off area 65a between the top line blade 42 and the counter blade 44 (see FIG. 12 ). The opposite end 66 of the suction line 65 is connected to a vacuum source (not shown here) of the suction device 64 .

In order to produce a seam starting top thread with a target seam overhang of at most 10 mm, a portion of the needle thread 13 is first transported from the top of the sewing workpiece to the bottom side of the sewing workpiece 15 at the top thread lifting position of the top thread raising portion 43 , where pin 10 passes through the The top line raises the opening of the portion 43 . Then, the top thread start 13 a is pulled out with the gripper 19 until the entire top thread start 13 a is located under the underside of the sewing workpiece 15 . After a short first stitch, then by activating the displacement drive 48 when the thread lever 8 is in the top dead center region, the top thread raising part 43 goes from the top thread raising position into the retracted top thread clamping position. With the needle thread starting portion 13 a clamped, a shorter stitch is formed, wherein the sewing needle 10 then no longer passes through the top thread pick-up 43 . After the second short stitch is completed, the clamping stopper driver 58 is activated and the clamping position stopper is transferred from the clamping position to the intermediate position, so that the top thread pick-up portion 43 and thus the top thread blade 42 are now transferred to Further retracted top wire cutting position. Here, the cutting edge of the top thread raising portion 43 cooperates with the abutting blade 44 to cut off the top thread starting portion 13a. The severed portion of the top thread starting portion 13 a is then sucked away by the suction device 64 .

After the two initial short stitches at the beginning of the seam, the sewing of the seam continues with the normal stitch length. The specification of the stitch length is provided by the controller 39 .

The remainder of the seam can now be formed by combining the top thread 13 and the bottom thread, not shown in detail here, in a double reversed seam. Then, the thread cutting process of the top thread 13 and the bottom thread is performed by the thread pulling blade 29 at the end of the seam.

The plan view according to FIG. 16 shows the seam 67 formed by the sewing assembly 40 at the beginning of the seam. The stitching direction extends in direction x to the left in FIG. 6 . Due to the top thread portion between the top thread blade 42 and the counter blade 44, the top thread start portion 13a where the seam 67 begins is so short that a maximum seam protrusion A of 10mm results.

It is also shown in Fig. 16 that the first two starting stitches _S1 , _S2 are shortened compared to the following stitches _S3 , ... _Su .

As an alternative to the above-described design of the shift drive 48 with a stop, the shift drive can also be designed as a stepper motor, so that the top wire lifts the part The various positions of 43 are equivalent to each stepping position of the stepping motor. These different step positions can be specified by the controller 39 .

40:Sewing machine components

41: Top Line Catcher

42: Top Line Blade

43: Top line provocation part

44: Butt blade

45: top wire clip; clamping spring

47: screw

48: shift drive; lifting cylinder

49: Guide pin

50:piston

51: piston rod

52: Slender hole

53: Mounting plate

54: threaded pin

55: Plastic body

57: Driver support plate

58: Clamp stop driver

59: Piston rod

60: stop body; stop plate

64: Suction device

65: suction pipe

65a: cut off area

66: Opposite end

Claims (7)

An assembly for producing a seam-starting top thread with a target seam overhang of up to 10 mm, having a top-thread catcher for raising the seam-starting top thread, wherein the top thread catcher has: with a top thread Top thread blades for lifting section, butt blade, top thread clamp, shift drive for top thread raising section, where top thread raising section can be shifted with a shift drive between the following positions: for lifting Seam start top thread top thread lifting position, seam start top thread top thread clamping position between top thread blade and top thread clamp, and top thread cutting position for top thread blade and butt joint Seam-starting top thread between blades, wherein said assembly is embodied such that said top thread raising position, said top thread clamping position and said top thread cutting position are in said top thread raising portion different positions from each other, and wherein the assembly includes an adjustable cutting position stop for defining the relative position of the top-line blade and the abutment blade in the top-line cutting position, the adjustable The cutting position stop has a stop body to which the top line blade is mounted and a guide pin in the region of the inclined wall portion of the stop body contact, and the stop body can be transverse to the The cutting motion direction of the topline blade is shifted for defining the relative position of the topline blade and the abutment blade. The assembly as claimed in claim 1, wherein said shifting drive is designed as exactly one drive which displaces said top wire lifting portion between said three positions. The assembly according to claim 1, wherein the displacement drive is designed as a linear drive, wherein a linear guide guides the displacement movement of the top wire provocation portion between the three positions. The assembly as claimed in claim 1 further has an adjustable clamping position stopper for defining the relative position of the top thread blade and the top thread clamp in the top thread clamping position. The assembly of claim 4, wherein the clamped position stop has a self-restraining threaded pin. The assembly as claimed in claim 1, further comprising a suction device for suctioning the severed top line portion. A sewing machine having an assembly as claimed in claim 1, having a driven needle bar with a sewing needle carried by it for guiding a top thread, and a needle for raising the top thread to form a thread track gripper.

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