TW201702450A - Stitch length-adjusting device for a sewing machine and sewing machine with such a stitch length-adjusting device - Google Patents

Abstract

A stitch length-adjusting device (25) for a sewing machine has a stop unit (26) for specifying stops for a lever body (27). The latter can be reset by pivoting about an adjusting axis (28) between a forward stitch stop position and a backward stitch stop position. The adjusting device (25) also has a stitch regulator gear (49), which is connected on the one hand to the lever body (27) and on the other hand to a transporter drive shaft. An assembly frame (52) of the stitch regulator gear (49) is connected in a rotationally secure manner to the lever body (27). This results in a stitch length-adjusting device with improved stability of a stitch length specification.

Description

Stitch length adjusting device for sewing machine and sewing machine having such stitch length adjusting device Reference to related application

The content of the German patent application DE 10 2015 207 998.8 is incorporated herein by reference.

Field of invention

The present invention relates to a stitch length adjusting device for a sewing machine. The present invention also relates to a sewing machine including such a stitch length adjusting device.

Background of the invention

A stitch length adjusting device for a sewing machine is known from DE 100 13 414 C1.

Summary of invention

An object of the present invention is to improve the stability of a stitch length specification (a designated value, a predetermined value) by a stitch length adjusting device.

According to the invention, the object is achieved by a stitch length adjusting device for a sewing machine, The stitch length adjusting device has a stop (limit) unit for specifying (defining, pre-specifying) a stop for the lever body, the lever body being pivotable by about the adjustment axis Adjustment between positions:--forward stitch stop position, the forward stitch stop position is used to specify the conveying motion of the sewing workpiece conveyor in the conveying direction of the sewing workpiece;--backward stitch stop position, the backward line The track stop position is for specifying a conveying motion of the sewing workpiece conveyor in an opposite direction of the conveying direction of the sewing workpiece, the stitch length adjusting device comprising a stitch adjuster gear, the stitch adjuster gear Connected to the lever body, on the other hand to the conveyor drive shaft; wherein the assembly frame of the stitch adjuster gear is coupled to the lever body in a rotationally fixed (non-rotatable) manner.

By specifying the conveying motion of the conveyor in the stitch length adjusting device, the specification of the corresponding stitch length can be defined. According to the invention, it has been recognized that the assembly frame of the stitch adjuster gear and the lever body - which can be adjusted between the stop positions for conveying the motion specifications - are rotationally fixed or torque-proof connections That is, the common rotational axis of the assembly frame and the lever body increases the stability of the stitch length adjusting device and correspondingly makes the accuracy and stability of the stitch length specification larger. Unwanted relative motion between the stitch adjuster gear and the lever body is avoided. It is also possible to have the stitch adjuster gear assembly frame and the lever body have an integral design.

The stop unit as an embodiment of the adjustment slider leads to the forward The stitching is coupled with a highly precise form fit of the specification of the rear stitch stop position, which in this embodiment is designed as an adjustment slider for the lever body, the adjustment slider being Pivoting about the adjustment axis to pivot between: a forward stitch slider position that forms the forward stitch stop position for specifying the sewing workpiece transport a conveying motion in the conveying direction of the sewing workpiece; - a backward stitching slider position, the backward stitching slider position forming the backward stitching stop position for specifying the sewing workpiece conveyor in the The conveying motion in the opposite direction of the conveying direction of the sewing workpiece.

An adjustment shaft extending along the adjustment axis is a particularly suitable member for connecting the lever body to the assembly frame in a rotationally fixed or torque-proof manner, the lever body and the assembly frame It is connected to the adjustment shaft in a rotationally fixed manner.

A setting drive operatively coupled to the lever body to set the lever body enables automatic adjustment between the forward stitch and the backward stitch. The set drive can be designed as a pneumatic cylinder.

The forward adjustment device includes a first forward stitch setting device and a second forward stitch setting device for designating by shifting at least one of the stop units a large forward stitch length in the conveying direction of the sewing workpiece, the second forward stitch setting means for specifying the conveying direction of the sewing workpiece by displacing at least one of the stopper units The second smaller forward stitch length. The forward adjustment device increases the level of comfort when operating the sewing machine.

The short stitch adjusting device is for specifying a short stitch length in a sewing workpiece conveying direction by shifting a short stitch stopper body for the short stitch lever body connected to the stitch adjuster gear, the short stitch length Less than the length of the forward stitch. This short track adjustment device allows the short stitch length to be additionally specified. Such a short stitch can be used, for example, for a line segment to be sutured at the end of the seam.

The assembly frame of the stitch adjuster gear is coupled to the short stitch lever body in a rotationally fixed manner, which ensures a suitable reliability height of the short stitch adjusting device.

Wherein the stop position of the short stitch lever body on the short stitch stop body can be specified by pre-defining the short stitch stop body about the stop body axis so that the short line can be easily adjusted Trace length.

A short stitch setting device operatively coupled to the short stitch lever body to set the short stitch lever body enables the sewing machine to be automatically set to a short stitch operation. The short track setting drive can be designed as a pneumatic cylinder.

In the stop position designation, the short-tracking lever body is on the short-track stop body by designating a stop of the short-track setting actuator of the driver body on the short-track stop body The designation of the stop position specifies that the short track lever body is prevented from being directly stopped on the short stitch body, thereby reducing wear of the short stitch lever body.

A calibration device for adjusting the length ratio between the forward stitch length and the backward stitch length enables fine adjustment of the length of the forward stitch on the one hand, and the other The length of the backward stitch can be finely adjusted. It is thus ensured for the backward stitch that the needle is accurately pierced at the same position in the sewing workpiece as for the forward stitch. The calibration device can be designed by the eccentric adjustment of the stop unit in order to specify the forward stitch and the backward stitch stop position of the lever body, and in particular by the eccentric adjustment of the adjustment slider.

The advantages of the sewing machine having the stitch length adjusting device according to the present invention correspond to those described above with reference to the stitch length adjusting device according to the present invention.

1‧‧‧ sewing machine

2‧‧‧Substrate

2a‧‧‧Substrate housing

3‧‧‧ column

3a‧‧‧Pole housing

4‧‧‧ Arm

4a‧‧‧ Arm housing

5‧‧‧Sewing machine housing

6‧‧‧ head

6a‧‧‧Head shell

7‧‧‧ Needle bar

8‧‧‧Clamping device

9‧‧‧Support plane

10‧‧‧Support plate

11‧‧‧track board

12‧‧‧Sewing workpiece conveyor

13‧‧‧Main housing parts

14‧‧‧ housing cover

15‧‧‧Bear axis

16‧‧‧Bear shaft drive motor

17‧‧‧ toothed belt

18‧‧‧ drive gear

19‧‧‧ drive shaft

20‧‧‧Bear gear

21‧‧‧lower shaft gear

22‧‧‧Tighten pulley

23‧‧‧Handwheel

24‧‧‧ Lower shaft

24a‧‧‧needle conveying shaft

24b‧‧‧ Needle bar slider

25‧‧‧Stripe length adjustment device

26‧‧‧stop unit, adjustment slider

27‧‧‧Leverage body

28‧‧‧Adjustment axis

29‧‧‧Bolts

30‧‧‧ Forward stitch bending area

31‧‧‧Backward track bending area

32, 38‧‧‧Set the drive

33, 39, 55‧ ‧ piston

34, 40‧‧‧ curved surface

35‧‧‧First forward adjustment device

36, 42‧‧‧ spherical free ends

37, 41‧‧‧ lever surface

43‧‧‧Second forward adjustment device

44‧‧‧calibration axis

45‧‧‧ calibration device

46‧‧‧Eccentric parts

47‧‧‧ Calibration adjustment screw

49‧‧‧Stroke adjuster gear

50‧‧‧Transmission lever

51‧‧‧Transport drive shaft

52‧‧‧ Assembly frame

53‧‧‧Adjustment axis

53a‧‧‧Eccentric lever

54‧‧‧Short track adjustment device

56‧‧‧Short Trace Setting Driver

58‧‧‧ Short track lever body

59‧‧‧Short-track stop body

60‧‧‧outer zone

61‧‧‧Bend opposing surface

62‧‧‧ pivot axis

63‧‧‧Assembled screws

64‧‧‧Rotating thread pin

Example embodiments of the present invention are explained in more detail below with reference to the accompanying drawings.

Figure 1 shows a rear view of the sewing machine in which the external sewing machine parts have been partially omitted; Figure 2 shows a front view of the sewing machine according to Figure 1, i.e. from the operator's side, in which the sewing machine has been omitted for closing The operator side of the housing and the housing cover of the inner and outer sewing machine parts; FIG. 3 shows a perspective view of the sewing machine according to FIG. 2; FIG. 4 shows the driving part of the sewing machine for driving the stitch forming tool and the upper and Lower sewing workpiece conveyor; FIG. 5 shows a cross-sectional view of the component of the stitch length adjusting device housed in the column of the sewing machine housing according to the line VV of FIG. 1, wherein these components of the stitch length adjusting device are shown Is located at the "large stitch length for forward stitch" position; Figure 6 shows a view similar to Figure 5 of the components of the adjustment device at the "back stitch" position; Figure 7 shows, from the operator's side, a detailed view of the sewing machine in the vicinity of the two adjustment wheels for setting the forward stitch length on the one hand and the rear stitch length on the other hand; Figure 8 shows the sewing machine according to Figure 7 A cross-sectional view of line VIII-VIII; FIG. 9 shows a partial cross-sectional view of the vicinity of the short stitch setting drive of the sewing machine from the viewing direction IX of FIG. 1, the short stitch setting drive being shown as being located at "maximum adjustable forward stitch length" Position; FIG. 10 shows a short stitch setting driver at the "short stitch" position; and FIG. 11 shows a cross-sectional view along line XI-XI of FIG.

detailed description

The sewing machine shown in Figs. 1 and 3 - in which the inner and outer members are partially omitted - has a base 2, a column 3 and an upper arm 4 which are arranged upright from the substrate 2. The substrate 2, the column 3, and the arm 4 are components of the sewing machine housing 5, and the sewing machine housing 5 has a substrate housing portion 2a, a pillar housing portion 3a, and an arm housing portion 4a. The arm 4 terminates in a head 6 having a head housing portion 6a.

In the vicinity of the head housing portion 6a, the sewing machine 1 has a stitch forming tool, that is, a needle bar 7 in which an organic needle (not shown) is fixed, and a wire gripper 8 schematically shown by a broken line in Fig. 1. The gripper 8 is arranged below the support plane 9 defined by the support plate 10. A portion of the support plate 10 is a track plate 11 (see Fig. 4). The stitch plate 11 has a central through opening for lower sewing the workpiece conveyor 12. The lower sewing workpiece conveyor 12 has a stitch hole through which the needle passes.

The sewing machine housing 5 has a cast main housing part 13 which is zero The piece 13 is designed to be open on the operating side, as shown in the views according to Figures 2 and 3. The main casing part 13 is designed as a single piece and includes a pillar housing portion 3a, an arm housing portion 4a and a head housing portion 6a. The main housing part 13 is configured such that it can be cast without a core in a coreless form.

In order to close the operator side of the sewing machine housing 5, a housing cover 14 is used, which is shown in cross section in Fig. 6 in a cutaway view. The housing cover 14 can be designed as a single piece or alternatively can also be designed as a plurality of parts. The housing cover 14 is made of plastic.

The stitch forming tool - that is, the needle bar 7 and the wire gripper 8 - is driven by the arm shaft 15. The arm shaft drive motor 16 (see FIGS. 3 and 4) is operatively coupled to the arm shaft 15 by a toothed belt 17.

The arm shaft drive motor 16 is attached to the arm housing portion 4a on the side of the housing that faces away from the operator side. The arm shaft drive motor 16 is mounted in a recess of the sewing machine housing 5. The axial extension of the arm shaft drive motor 16 corresponds to the width of the pillar housing portion 3a.

The drive gear 18 meshes with a toothed belt 17 (see FIG. 9) that is coupled to the drive shaft 19 of the arm shaft drive motor 16 in a rotationally fixed manner. The arm shaft drive motor 16 is firmly attached to the housing in the vicinity of the arm housing portion 4a.

The drive shaft 19 of the arm shaft drive motor 16 extends parallel to the arm shaft 15. The drive shaft 19 is at a greater distance from the support plane 9 than the arm shaft 15.

The drive means, i.e., the toothed belt 17, is disposed on the opposite side of the arm shaft drive motor 16 from the head housing portion 6a. The drive motor 16 does not represent an extension of the arm shaft 15. The drive shaft 19 is not aligned with the arm shaft 15.

The arm shaft gear 20 and the lower shaft gear 21 mesh with the toothed belt 17. The toothed belt 17 travels between the drive gear 18 and the arm shaft gear 20 on the tension pulley 22. The arm shaft gear 20 is disposed between the arm housing portion 4a and the hand wheel 23 of the sewing machine 1, and the hand wheel 23 is coupled to the arm shaft 15 in a rotationally fixed manner. The lower shaft gear 21 is coupled to the lower shaft 24 in a rotationally fixed manner, and the lower shaft 24 drives the gripper 8 and other components.

Parallel to the arm shaft 15 is a needle transport shaft 24a by which the oscillating motion of the needle bar slider 24b is effected, which is derived from the rotation of the arm shaft. Thus, in a known manner, the needle transport is performed in such a manner as to be transported through the sewing workpiece of the sewing machine 1.

The sewing machine 1 is capable of performing upper and lower conveyance of the sewing workpiece by the needle bar slider 24b and the lower conveyor 12.

The sewing machine 1 has a stitch length adjusting device 25, and the components of the stitch length adjusting device 25 are specifically shown in Figs. By the stitch length adjusting device 25, it is possible to specify a large stitch length for the forward conveyance of the sewing workpiece in the sewing workpiece conveying direction x (see FIG. 3), which can be in the opposite direction (-x) of the sewing workpiece conveying direction x. The sewing workpiece conveyance specifies the length of the backward stitch, and a short stitch length can be specified for the line segment particularly in the sewing workpiece conveying direction x. In addition, the length ratio between the forward stitch length and the backward stitch length can be calibrated.

The stitch length adjusting device 25 has a stop unit 26 for specifying a stop for the lever body 27. The lever body 27 can be re-adjusted about the adjustment axis 28. The stop unit 26 is designed as an adjustment slider for the bolt 29 of the lever body 27 and is also referred to as a jaw.

The forward stitch stop position for specifying the conveyance motion of the sewing workpiece conveyer 12 in the sewing workpiece conveyance direction x shown in FIG. 5 and the sewing workpiece conveyor 12 for sewing specified in FIG. The lever body 27 is adjusted between the backward stitch stop positions of the conveying motion in the opposite direction (-x) of the workpiece conveying direction x. The forward stitch stop position is the forward stitch slider position in which the bolt 29 abuts against the forward stitch bending region 30 of the adjustment slider 26. The backward stitch stop position is designed as a rearward track slider position in which the bolt 29 abuts against the backward stitch curved region 31 of the adjustment slider 26.

In order to adjust the lever body 27 between the forward stitch stop position and the backward stitch stop position, a setting drive 32 is used, which is designed as a pneumatic cylinder having a piston 33. The piston 33 is fully retracted at the forward stitch stop position according to Fig. 5, and protrudes to the extent of the backward stitch stop position according to Fig. 6 such that the lever body 27 of Figs. 5 and 6 surrounds the adjustment axis 28 Move counterclockwise to the backward stitch stop position. The piston 33 thus abuts against the curved surface 34 of the lever body 27.

Figures 5 and 6 show the stop unit 26, i.e. the adjustment slider, located at the "large stitch length" position. In order to specify the large forward stitch length at the position according to Fig. 5 and the corresponding large backward stitch length at the position of Fig. 6, the first forward adjustment means 35 is used. The first forward adjustment device 35 is formed by an adjustment wheel that mates with an axially displaceable threaded spindle.

The spherical free end 36 of the threaded mandrel abuts against the lever surface 37 of the stop unit 26 to specify its "large stitch length" position. In this "large stitch length" position, the stop unit 26 is pretensioned by a prestressed spring. By setting adjustment The wheel 35 is capable of fine adjustment of the position and thus is capable of defining a large stitch length.

By additionally setting the drive 38, the stop unit 26 can be reset between the "large stitch length" position shown in Figures 5 and 6 and the "small stitch length" position not shown in the figure. In the "small stitch length" position, the piston 39, which is also designed as the setting actuator 38 of the pneumatic cylinder, projects and pushes against the curved surface 40 of the stop unit 26 until its additional lever surface 41 abuts against the second direction. The spherical free end 42 of the threaded mandrel of the front adjustment device 43. Like the first forward adjustment device 35, the second forward adjustment device 43 is also designed as an adjustment wheel.

When adjusted between the "large stitch length" position and the "small stitch length" position, the stop unit 26 pivots about the eccentrically mounted calibration shaft 44. The calibration axis 44 is part of a calibration device for adjusting the length ratio between the forward stitch length and the backward stitch length. The eccentric 46 is mounted on the calibration shaft 44 and secured by a calibration adjustment screw 47 (see Figure 8). By releasing the calibration adjustment screw 47, the eccentric 46 can be rotated about the calibration axis 44. The calibration adjustment screw 47 is accessible from the outside via an elongated aperture 48 in the user side. The z-direction extension of the elongated aperture 48 defines a calibration adjustment region of the eccentric 46.

In an alternative embodiment of the calibration device 45, not shown, the eccentric 46 is releasably coupled to the stop unit or adjustment slider 26 by a calibration adjustment screw. In this variation, the stitch length is determined by adjusting the common rotation of the slider 26 and the eccentric 46 about the calibration axis 44. The calibration adjustment screw in this variation can be accessed externally via a curved elongated aperture that specifies the allowable calibration adjustment range of the eccentric 46.

A part of the stitch length adjusting device 25 is designed to be flat in a known manner. A track adjuster gear 49 of a tab gear. The stitch adjuster gear 49 is connected on the one hand to the lever body 27 and on the other hand to the transport drive shaft 51 via a transmission lever 50 and a lever joint, which is also represented as a stitch adjuster shaft. The stitch adjuster shaft 51 is designed as a pivot shaft. The pivot angle of the stitch adjuster shaft 51 about its longitudinal axis is a measure of the transport motion of the lower sewing workpiece transporter 12 in the opposite direction of the sewing workpiece transport direction or in the sewing workpiece transport direction. The stitch adjuster shaft 51 is connected to the lower sewing workpiece conveyor 12 by further deflection.

The assembly frame 52 of the stitch adjuster gear 49 is coupled to the lever body 27 in such a manner as to be rotationally fixed or prevented from generating torque, and the lever body 27 is engaged with the adjustment slider 26. Therefore, the assembly frame 52 is not rotatable relative to the lever body 27. The rotationally fixed connection is achieved by an adjustment shaft 53 extending along the adjustment axis 28. In an alternative embodiment, the lever body 27 and the assembly frame 52 can be accurately positioned relative to each other, for example via a pin connection or a screw connection, without releasing a fixation that causes a degree of freedom of displacement about the adjustment axis. . As another alternative, the lever body 27 and the assembly frame 52 of the stitch adjuster gear 49 can be designed as a single piece.

The stitch adjuster gear 49 transmits the driving motion transmitted by the arm shaft 15 via the eccentric lever 53a into the driving motion of the transmission lever 50.

Referring to Figures 9 and 10, a short stitch adjusting device 54 for specifying a short stitch length in the sewing workpiece conveying direction x is described hereinafter. The short stitch length is especially used for the line segment at the end of the seam. The short stitch length is smaller than the small forward stitch length described above.

Figure 9 shows the short stitch adjustment device 54 in the neutral position. At this neutral position, the piston 55 of the short stitch setting drive 56 designed as a pneumatic cylinder is retracted. The piston 55 represents the drive body of the short stitch setting driver. The pre-stressed spring pre-stresses the curved surface of the short-track lever body 58 against the free end of the piston 55.

The short-track lever body 58 is connected to the adjustment shaft 53 in such a manner as to be fixed in rotation or to prevent the generation of torque, and the lever body 27 that is engaged with the adjustment slider 26 via the bolt 29 is also connected by the adjustment shaft in a rotationally fixed manner.

Figure 10 shows the stitch adjustment device 54 located at the "short stitch for line segment" position. The short stitch setting drive 56 has the piston 55 extended so that the short stitch lever body 58 rotates counterclockwise about the adjustment shaft 53 in FIGS. 9 and 10.

The stitch adjuster gear 49 is adjusted accordingly by the pivoting of the short stitch lever body 58, which results in adjustment of the short stitch drive of the stitch adjuster shaft 51.

The short stitch length is specified by the short stitch stop body 59. At the "short stitch for line segment" position according to Figures 10 and 11, the outer peripheral band 60 of the piston 55 of the short stitch setting drive 56 strikes the curved opposing surface 61 of the short stitch stop body 59, thereby limiting and defining the piston stroke The position of the short stitch lever body 58 is thus limited and limited. The short track stop body 59 is pivotable about a pivot axis 62 provided by an assembly screw 63 for the short stitch stop body 59. The assembly screw 63 thus represents the stop body shaft.

The designation of the stop position is made by the corresponding pivoting of the short track stop body 59 around the stop body shaft 63. This pivoting is achieved by rotating a threaded pin 64 that is rotated into the short stitch stop body 59 and against the housing. The wall 65 is fixed to the machine side. The adjustment head 66 of the threaded pin 64 can be freely accessed from the outside.

The drivers 16, 32, 38 and 56 are controlled by a central control unit 67, shown in phantom in Fig. 1.

The sewing machine 1 allows the amount of stitches of more than 2,000 stitches per minute, and is usually 3,000 stitches per minute.

The sewing machine 1 can be used to suture the sewing workpiece with a material thickness of 4 mm or more.

The needle thickness (thickness) of the sewing machine 1 can be larger than 1.1 mm in diameter (needle of the nominal size 110). The needle thickness can be greater than 1.25 mm, can be greater than 1.5 mm, can be greater than 1.75 mm, and can also be greater than 2 mm.

The wire thickness can be greater than 0.3 mm in diameter. In particular, the wire thickness can be greater than the nominal size 60 (the wire weight of 60 m is 1 g). In particular, the wire thickness may be greater than 0.5 mm, greater than 0.7 mm, greater than 0.9 mm or 1 mm in diameter.

10‧‧‧Support plate

25‧‧‧Stripe length adjustment device

26‧‧‧stop unit, adjustment slider

27‧‧‧Leverage body

28‧‧‧Adjustment axis

29‧‧‧Bolts

30‧‧‧ Forward stitch bending area

31‧‧‧Backward track bending area

32‧‧‧Setting the drive

39‧‧‧Piston

40‧‧‧Bend surface

35‧‧‧First forward adjustment device

36‧‧‧Spherical free end

37, 41‧‧‧ lever surface

38‧‧‧Setting the drive

42‧‧‧ spherical free end

43‧‧‧Second forward adjustment device

44‧‧‧calibration axis

46‧‧‧Eccentric parts

49‧‧‧Stroke adjuster gear

50‧‧‧Transmission lever

51‧‧‧Transport drive shaft

52‧‧‧ Assembly frame

53‧‧‧Adjustment axis

53a‧‧‧Eccentric lever

Claims (13)

A stitch length adjusting device for a sewing machine, having a stop unit for specifying a stop for a lever body, the lever body being adjustable between the following positions by pivoting about an adjustment axis :-- Forward stitch stop position, the forward stitch stop position is used to specify the conveying motion of the sewing workpiece conveyor in the conveying direction of the sewing workpiece; -- the backward stitch stop position, the backward stitch stop position Means for specifying a conveying movement of the sewing workpiece conveyor in a direction opposite to the conveying direction of the sewing workpiece, comprising a stitch adjuster gear connected to the lever body on the one hand and to the lever body on the other hand a conveyor drive shaft; - wherein the assembly frame of the stitch adjuster gear is coupled to the lever body in a rotationally fixed manner. A stitch length adjusting device according to claim 1, wherein the stop unit is designed as an adjustment slider for the lever body, the adjustment slider being pivotable by about the adjustment axis Adjusted between: - the forward stitch slider position, the forward stitch slider position forming the forward stitch stop position for specifying the sewing workpiece conveyor in the sewing workpiece conveying direction Conveying motion; -- rearward track slider position, the backward stitch slider position forming the A backward stitch stop position for specifying a conveying motion of the sewing workpiece conveyor in an opposite direction to the conveying direction of the sewing workpiece. A stitch length adjusting device according to claim 1, comprising an adjustment shaft extending along the adjustment axis, the lever body and the assembly frame being coupled to the adjustment in a rotationally fixed manner axis. A stitch length adjusting device according to claim 1, comprising a setting driver operatively coupled to the lever body to set the lever body. The stitch length adjusting device according to claim 1, characterized by comprising a first forward stitch setting device for causing at least one stopper in the stopper unit Shift to specify a large forward stitch length in the conveying direction of the sewing workpiece. A stitch length adjusting device according to claim 5, characterized by comprising a second forward stitch setting means for making at least one of the stopper units Shift to specify a second smaller forward stitch length in the conveying direction of the sewing workpiece. A stitch length adjusting device according to claim 1, characterized by comprising short stitch setting means for making a short line for the short stitch lever body connected to the stitch adjuster gear The track stop body is displaced to specify a short stitch length in the sewing workpiece conveying direction, the short stitch length being less than the forward stitch length. A stitch length adjusting device according to claim 7, characterized in that The assembly frame of the stitch adjuster gear is coupled to the short stitch lever body in a rotationally fixed manner. The stitch length adjusting device according to claim 7, wherein a stop position of the short stitch lever body on the short stitch stop body can surround the stop body by the short stitch stop body Axis shift to specify. The stitch length adjusting device of claim 7, comprising a short stitch setting driver operatively coupled to the short stitch lever body to set the short stitch lever body. The stitch length adjusting device according to claim 10, wherein the position of the stop position of the short stitch lever body on the short stitch stop body is specified by specifying the short stitch setting driver body of the driver The stop on the short track stop body is performed. A stitch length adjusting device according to claim 1, comprising a calibration device for adjusting a length ratio between a forward stitch length and a backward stitch length. A sewing machine having a stitch length adjusting device for a sewing machine, the stitch length adjusting device having: a stop unit for specifying a stop of the lever body, the lever body being able to pass around the adjustment axis Pivot and adjust between: --- Forward stitch stop position, which is used to specify the sewing workpiece conveyor in the sewing workpiece conveying direction Sending motion; -- a backward stitch stop position for specifying a conveying motion of the sewing workpiece conveyor in a direction opposite to the conveying direction of the sewing workpiece, including a stitch adjuster gear, a stitch adjuster gear is coupled to the lever body on the one hand and to the conveyor drive shaft on the other hand; - wherein the assembly frame of the stitch adjuster gear is coupled to the lever body in a rotationally fixed manner .