EP3088591B1 - Stitch length adjustment device for a sewing machine and sewing machine with such a stitch length adjustment device - Google Patents

Description

The present patent application takes the priority of the German patent application DE 10 2015 207 998.8 claim, the contents of which are incorporated herein by reference.

The invention relates to a stitch length adjusting device for a sewing machine. Furthermore, the invention relates to a sewing machine with such a stitch length adjusting device.

A stitch length adjusting device for a sewing machine is known from the DE 100 13 414 C1 , The JP 06292778 A also describes a stitch length adjusting device for a sewing machine. The DE 10 2007 004 549 A1 describes a feed adjusting device of a sewing machine. The EP 2 325 364 A2 describes a mass transfer device of a sewing machine. The CH-PS 290562 describes a reversible fabric feed device on a sewing machine. The EP 2 617 884 A1 describes a mass transfer adjustment of a sewing machine.

It is an object of the present invention to improve stability of stitch length setting by the stitch length adjusting device.

This object is achieved by a stitch length adjusting device with the features specified in claim 1.

About a specification of the transport movements of the carrier is given in the stitch length adjusting device, the specification of the respective stitch length. According to the invention it has been recognized that a rotationally fixed connection of the adjusting frame of the Stichstellergetriebes with the convertible between the stop positions for transport movement specification lever body, ie a common axis of rotation of the adjusting frame and the lever body leads to an increased stability of the stitch length adjusting device and correspondingly to a higher precision and stability of the stitch length specification. Undesirable relative movements between the Stichstellergetriebe and the lever body are avoided. Also a one-piece design the stitch regulator gear box with the lever body is possible.

The execution of the stop unit as Einstellkulisse according to claim 2 leads to a high-precision positive coupling of the specification of forward stitch and reverse stitch stop position.

An actuating shaft according to claim 3 is a particularly suitable component for the rotationally fixed connection of the lever body with the adjusting frame.

A changeover drive according to claim 4 allows automatic switching between forward and reverse stitch. The Umstellantrieb can be designed as a pneumatic cylinder.

Forward adjusting devices according to claims 5 and 6, respectively, increase the convenience of operating the sewing machine.

A short stitch adjustment device according to claim 7 allows the additional specification of a short stitch length. Such a short stitch is used, for example, in the thread section at the end of a seam to be sewn.

A rotationally fixed connection according to claim 8 ensures a correspondingly high stability of the short stitch adjustment device.

A predefinable stop position according to claim 9 leads to a simple adjustment of a short stitch length.

A short stitch reversing drive according to claim 10 allows automatic switching of the sewing machine in the short stitch operation. The short stitch reversing drive can be designed as a pneumatic cylinder.

A stop position specification according to claim 11 avoids a direct stop of the short stitch lever body on the short stitch stop body and thus reduces wear of the short stitch lever body.

A calibration device according to claim 12 allows a fine balance of the lengths of forward stitch on the one hand and reverse stitch on the other. It is then ensured that the reverse stitch the needle punctures exactly at the same position in the fabric as the forward stitch. The calibration device can be embodied via an eccentric adjustment of the stop unit for specifying the forward stitch and reverse stitch stop position of the lever body and, in particular, by an eccentric adjustment of the adjusting slide.

The advantages of a sewing machine according to claim 13 correspond to those which have already been explained above with reference to the stitch length adjusting device according to the invention.

Fig. 1

eine Rückansicht einer Nähmaschine, wobei externe Maschinenkomponenten teilweise weggelassen sind;

Fig. 2

eine Vorderansicht, also eine Ansicht von einer Bedienerseite her, der Nähmaschine nach Fig. 1, wobei eine Gehäuseabdeckung zum Verschließen der Bedienerseite eines Nähmaschinengehäuses sowie interne und auch externe Maschinenkomponenten weggelassen sind;

Fig. 3

eine perspektivische Ansicht der Nähmaschine nach Fig. 2;

Fig. 4

Antriebskomponenten der Nähmaschine zum Antreiben von Stichbildungswerkzeugen sowie eines oberen und eines unteren Nähguttransports;

Fig. 5

einen Schnitt gemäß Linie V-V in Fig. 1 durch Komponenten einer Stichlängen-Stellvorrichtung, die in einem Ständer des Nähmaschinengehäuses untergebracht sind, wobei die Stichlängen-Stellvorrichtungskomponenten in der Position "große Stichlänge bei Vorwärtsstich" dargestellt sind;

Fig. 6

in einer zur Fig. 5 ähnlichen Ansicht die Stellvorrichtungskomponenten in der Position "Rückwärtsstich";

Fig. 7

von der Bedienerseite her eine Detailansicht der Nähmaschine im Bereich zweier Einstellräder zur Vorgabe einerseits einer Vorwärts-Stichlänge und andererseits einer RückwärtsStichlänge;

Fig. 8

einen Schnitt gemäß Linie VIII-VIII in Fig. 7;

Fig. 9

eine im Bereich eines Kurzstich-Umstellantriebs teilweise geschnittene Ansicht der Nähmaschine aus Blickrichtung IX in Fig. 1, dargestellt in der Umstellposition "größte einstellbare Vorwärtsstichlänge";

Fig. 10

den Kurzstich-Umstellantrieb in der Position "Kurzstich"; und

Fig. 11

einen Schnitt gemäß Linie XI-XI in Fig. 10.

An embodiment of the invention will be explained in more detail with reference to the drawing. In this show:

Fig. 1

a rear view of a sewing machine, wherein external machine components are partially omitted;

Fig. 2

a front view, so a view from an operator side, the sewing machine after Fig. 1 , wherein a housing cover for closing the operator side of a sewing machine housing as well as internal and external machine components are omitted;

Fig. 3

a perspective view of the sewing machine after Fig. 2 ;

Fig. 4

Drive components of the sewing machine for driving stitching tools and an upper and a lower fabric transport;

Fig. 5

a section along line VV in Fig. 1 by components of a stitch length adjusting device accommodated in a stand of the sewing machine housing, the stitch length adjusting device components being shown in the position "large stitch length in forward stitch";

Fig. 6

in a to Fig. 5 similar view the Stellstellrichtungskomponenten in the position "backward stitch";

Fig. 7

from the operator side a detailed view of the sewing machine in the range of two dials to specify on the one hand a forward stitch length and on the other hand, a RückwärtsStichlänge;

Fig. 8

a section according to line VIII-VIII in Fig. 7 ;

Fig. 9

a section of the sewing machine partially cut in the region of a short stitch reversing drive from the direction of view IX in Fig. 1 , shown in the changeover position "largest adjustable forward stitch length";

Fig. 10

the short stitch reversing drive in the "short stitch"position; and

Fig. 11

a section along line XI-XI in Fig. 10 ,

One in the Fig. 1 and 3 Sewing machine 1 illustrated with partial omission of internal and external components has a base plate 2, a stand 3 upstanding therefrom and an upper arm 4. The base plate 2, stand 3 and arm 4 are parts of a sewing machine housing 5 having a base plate housing portion 2a, a stator housing section 3a and an arm housing section 4a. The arm 4 terminates in a head 6 with a head housing portion 6a.

In the area of the head housing section 6 a, the sewing machine 1 has stitch forming tools, namely a needle bar 7 with a sewing needle (not shown) attached thereto and one in the Fig. 1 The gripper 8 is arranged below a support plane 9, which is defined by a support plate 10. Part of the support plate 10 is a throat plate 11 (see. Fig. 4 ). The needle plate 11 has a central passage opening for a lower material feed conveyor 12. This in turn has a tap hole for the passage of the sewing needle.

The sewing machine housing 5 has a cast main body portion 13, which is made open on an operator side, as the views of the Fig. 2 and 3 can be seen. The main housing part 13 is in one piece and includes the stator housing portion 3a, the arm housing portion 4a and the head housing portion 6a. The main housing part 13 is designed so that it can be cast without undercut in a core-free form.

To close the operator side of the sewing machine housing 5 is a housing cover 14, which in the Fig. 6 broken in section is shown. The housing cover 14 may be made in one piece or alternatively also in several parts. The housing cover 14 is made of plastic.

The stitch forming tools, ie the needle bar 7 and the gripper 8, are driven by an arm shaft 15. With the arm shaft 15 is a arm shaft drive motor 16 (see. Fig. 3 and 4 ) via a toothed belt 17 in operative connection.

The arm shaft drive motor 16 is mounted on the arm housing portion 4a on a side remote from the operator side of the housing. The arm shaft drive motor 16 is received in a recess of the sewing machine housing 5. An axial extent of the arm shaft drive motor 16 corresponds to a width of the stator housing section 3a.

With the toothed belt 17 meshes a drive gear 18 (see. Fig. 9 ), which is non-rotatably connected to a drive shaft 19 of the arm shaft drive motor 16. The arm shaft drive motor 16 is mounted fixed to the housing in the region of the arm housing section 4a.

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

The drive means, that is the toothed belt 17, is arranged on a side of the arm shaft drive motor 16 opposite the head housing section 6a. The drive motor 16 is not an extension of the arm shaft 15. The drive shaft 19 is not aligned with the arm shaft 15th

Between the drive gear 18 and the arm shaft gear 20, the toothed belt 17 passes through a tension pulley 22. The arm shaft gear 20 is interposed between the arm housing portion 4a and a handwheel rotatably connected to the arm shaft 15 23 of the sewing machine 1 is arranged. The lower shaft gear 21 is rotatably connected to a lower shaft 24 through which, inter alia, the gripper 8 is driven.

Parallel to the arm shaft 15 extends a needle transport shaft 24a over which, derived from the Armwellendrehung, a swinging movement of a Nadelstangenkulisse 24b takes place. By way of this, in a manner known per se, a needle transport as a material feed is provided by the sewing machine 1.

On the other hand, the sewing machine 1 allows both upper and lower feed for the sewing material via the needle bar link 24b on the one hand and via the lower feed dog 12 on the other hand.

The sewing machine 1 has a stitch length adjusting device 25, of the components in particular in the Fig. 4 to 10 are shown. With the stitch length adjusting device 25, a large stitch length during the forward transport of sewing material in a workpiece conveying direction x (see FIG. Fig. 3 ), a backward stitch length during the fabric transport (-x) against the fabric transport direction x and a short stitch stitch length in the fabric transport direction x, in particular for a thread section, are specified. In addition, an aspect ratio between the forward stitch length and the back stitch length can be calibrated.

The stitch length adjusting device 25 has a stop unit 26 for specifying stops for a lever body 27, which can be switched around an adjusting axis 28. The stop unit 26 is formed as Einstellkulisse for a bolt 29 of the lever body 27 and is also referred to as throat.

The lever body 27 is changeable between a in the Fig. 5 shown forward stitch stop position for specifying a transport movement of the material to be transported 12 in the fabric transport direction x and one in the Fig. 6 shown reverse stitch stop position for specifying a transport movement of the material to be transported 12 opposite (-x) the fabric transport direction x. The forward stitch stop position is a forward stitched gate position wherein the pin 29 abuts a forward stitch curve portion 30 of the adjustment gate 26. The reverse stitch stop position is formed as a reverse stitched gate position in which the pin 29 abuts against a reverse stitch curve portion 31 of the adjustment gate 26.

For switching the lever body 27 between the forward stitch stop position and the reverse stitch stop position is a Umstellantrieb 32, which is designed as a pneumatic cylinder with a piston 33. The piston 33 is in the forward stitch stop position after Fig. 5 fully retracted and behind in the reverse stitch stop position Fig. 6 extended so far until the lever body 27 in the Fig. 5 and 6 counterclockwise about the adjusting axis 28 is pivoted in the reverse stitch stop position. The piston 33 rests against an arcuate surface 34 of the lever body 27.

The Fig. 5 and 6 show the stopper unit 26, so the Einstellkulisse, in the position "large stitch length". To specify the large forward stitch length in the position after Fig. 5 and the corresponding large back stitch length in the position Fig. 6 serves a first forward adjustment 35. The latter is formed by a dial, which cooperates with an axially displaceable threaded spindle.

A crowned running, free end 36 of the threaded spindle is located on a lever surface 37 of the stopper unit 26 to specify their position "large stitch length". In this position "large stitch length", the stop unit 26 is biased by means of a biasing spring. About an adjustment of the dial 35, this position can be fine-adjust and thus specify the large stitch length.

By means of a further Umstellantriebes 38, the stopper unit 26 can be switched between in the Fig. 5 and 6 shown position "large stitch length" and a position "small stitch length", which is not shown in the drawing. In the position "small stitch length" is a piston 39 of the likewise designed as a pneumatic cylinder Umstellantriebs 38 extended and presses on an in turn arcuate surface 40 of the stopper unit 26 until the further lever surface 41 abuts against again convex free end 42 of a threaded spindle of a second forward-adjusting 43. The second forward adjustment device 43, like the first forward adjustment device 35, is also designed as a dial.

When switching between the positions "large stitch length" and "small stitch length", the stop unit 26 is pivoted about an eccentrically mounted calibration shaft 44. The calibration shaft 44 is part of a calibration device 45 for setting a length ratio between a forward stitch length and a backward stitch length. An eccentric 46 is mounted on the calibration shaft 44 and a calibration adjustment screw 47 (see. Fig. 8 ) fixed. By loosening the calibration adjustment screw 47, the eccentric 46 can be rotated about the calibration shaft 44. The calibration adjustment screw 47 is accessible from the outside via a slot 48 from the operator side. A z-extension of the slot 48 limits a calibration adjustment range of the eccentric 46.

In an alternative, not shown embodiment of the calibration device 45 of the eccentric 46 is releasably connected by means of a calibration adjustment with the stop unit or the Einstellkulisse 26. In this variant, an adjustment of the stitch length results from the common rotation of the Einstellkulisse 26 and the eccentric 46 to the Kalibrierwelle 44. The calibration adjustment in this variant is accessible from the outside via a curved slot, which specifies a permissible calibration adjustment of the eccentric 46 ,

Part of the stitch length adjusting device 25 is a Stichstellergetriebe 49, which is designed in a conventional manner as a lashing gear. The Stichstellergetriebe 49 is connected on the one hand to the lever body 27 and the other via a transmission lever 50 and a lever deflection with a feed dog drive shaft 51, which is also referred to as Stichstellerwelle. The Stichstellerwelle 51 is designed as a rocking shaft. An oscillation angle of the stitcher shaft 51 about its longitudinal axis is a measure of the transport movement of the lower material conveyor 12 in or against the material to be conveyed. Via a further deflection, the stitcher shaft 51 is connected to the lower material feed conveyor 12.

An adjusting frame 52 of the Stichstellergetriebes 49 is rotatably connected to the lever body 27, which cooperates with the Einstellkulisse 26 connected. This rotationally fixed connection via an actuating shaft 53, which extends along the control axis 28. In an alternative embodiment, the lever body 27 and the adjusting frame 52 may also be connected to one another, for example via a pin connection or a screw connection, in a position determined precisely relative to one another without releasing a fixation by a displacement degree. As a further alternative, it is possible to carry out the lever body 27 in one piece with the adjusting frame 52 of the Stichstellergetriebes 49.

The Stichstellergetriebe 49 transmits one of the arm shaft 15 via an eccentric lever 53 a transmitted drive movement to a drive movement of the transmission lever 50th

Based on Fig. 9 and 10 Below is a short stitch adjustment 54 for specifying a short stitch stitch length in the Sewing material transport direction x described. The short stitch length is used in particular for the thread section at the end of a seam. The short stitch length is smaller than the small forward stitch length explained above.

Fig. 9 shows the short stitch adjuster 54 in a neutral position. In this a piston 55 of a turn designed as a pneumatic cylinder short stitch Umstellantriebs 56 is retracted. The piston 55 constitutes a drive body of the short stitch reversing drive. Biased by a biasing spring, an arcuate surface 57 of a short stitch lever body 58 bears against the free end of the piston 55.

The short stitch lever body 58 is rotatably connected to the actuating shaft 53, with which also the lever body 27, which cooperates via the pin 29 with the Einstellkulisse 26, is rotatably connected.

Fig. 10 shows the short stitch adjustment 54 in the position "short stitch for the thread section". The piston 55 of the short stitch Umstellantriebs 56 is extended and accordingly the short stitch lever body 58 in the Fig. 9 and 10 pivoted counterclockwise about the control shaft 53.

By this pivoting of the short stitch lever body 58 results in a corresponding adjustment of the Stichstellergetriebes 49, which leads to the short stitch drive the Stichstellerwelle 51.

A specification of the short stitch stitch length via a short stitch stop body 59. In the position "short stitch for the thread section" after the 10 and 11 beats a circumferential collar 60 of the piston 55 of the Short stitch Umstellantriebs 56 on an arcuate counter surface 61 of the short stitch stop body 59, whereby the piston stroke and thus the position of the short stitch lever body 58 is limited and defined. The short stitch stop body 59 is pivotable about a pivot axis 62, which is predetermined by a mounting screw 63 for the short stitch stop body 59. The mounting screw 63 thus represents a stopper body shaft.

A specification of the stop position is carried out by a corresponding pivoting of the short stitch stop body 59 to the stop body shaft 63. This pivoting is done by turning a threaded pin 64 which is screwed into the short stitch stop body 59 and machine side against a fixed wall 65 is supported. From the outside, an adjusting head 66 of the threaded pin 64 is freely accessible.

The drives 16, 32, 38 and 56 are controlled via a central control device 67, which in the Fig. 1 indicated by dashed lines.

The sewing machine 1 allows a stitch count of more than 2,000 stitches per minute and typically 3,000 stitches per minute.

With the sewing machine 1 sewing material can be sewn with a material thickness of more than 4 mm.

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

A thread thickness can be thicker than 0.3 mm in diameter. In particular, the thread thickness may be thicker than nominal 60 (60 m thread weigh 1 g). In particular, the thread thickness can be thicker than 0.5 mm, as 0.7 mm, as 0.9 mm or as 1 mm in diameter.

Claims (13)

1. Stitch length-adjusting device (25) for a sewing machine (1)

   - with a stop unit (26) for specifying stops for a lever body (27), which can be adjusted by pivoting about an adjusting axis (28) between

   -- a forward stitch stop position for specifying a transport movement of a sewing workpiece transporter (12) in a sewing workpiece transport direction (x),

   -- a backward stitch stop position for specifying a transport movement of the sewing workpiece transporter (12) opposite (-x) the sewing workpiece transport direction (x),

   - comprising 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 (51),

   characterised in that
   an assembly frame (52) of the stitch regulator gear (49) is connected in a rotationally secure manner to the lever body (27).
2. Adjusting device according to claim 1, characterised in that the stop unit (26) is designed as an adjusting slide for the lever body (27), which can be adjusted by pivoting about the adjusting axis (28) between

   -- a forward stitch slide position, which forms the forward stitch stop position, for specifying the transport movement of the sewing workpiece transporter (12) in the sewing workpiece transport direction (x),

   -- a backward stitch slide position, which forms the backward stitch stop position, for specifying the transport movement of the sewing workpiece transporter (12) opposite (-x) the sewing workpiece transport direction (x).
3. Adjusting device according to claim 1 or 2, characterised by an adjusting shaft (53) running along the adjusting axis (28), to which the lever body (27) and the assembly frame (52) are connected in a rotationally secure manner.
4. Adjusting device according to any one of claims 1 to 3, characterised by a switchover drive (32), which is in operative connection with the lever body (27) for switching over the latter.
5. Adjusting device according to any one of claims 1 to 4, characterised by a first forward stitch adjusting device (35) for specifying a large forward stitch length in the sewing workpiece transport direction (x) by displacing at least one stop (30, 31) of the stop unit (26).
6. Adjusting device according to claim 5, characterised by a second forward stitch adjusting device (43) for specifying a second, smaller forward stitch length in the sewing workpiece transport direction (x) by displacing at least one stop (30, 31) of the stop unit (26).
7. Adjusting device according to any one of claims 1 to 7, characterised by a short stitch adjusting device (54) for specifying a short stitch length in sewing workpiece transport direction (x), which is smaller than a forward stitch length, by displacing a short stitch stop body (59) for a short stitch lever body (58), which is connected to the stitch regulator gear (49).
8. Adjusting device according to claim 7, characterised in that the assembly frame (52) of the stitch regulator gear (49) is connected in a rotationally secure manner to the short stitch lever body (58).
9. Adjusting device according to claim 7 or 8, characterised in that a stop position of the short stitch lever body (58) on the short stitch stop body (59) is specifiable by displacing the short stitch stop body (59) about a stop body shaft (63).
10. Adjusting device according to any one of claims 7 to 9, characterised by a short stitch switchover drive (56) which is in operative connection with the short stitch lever body (58) for switching over the latter.
11. Adjusting device according to claim 10, characterised in that the specification of the stop position of the short stitch lever body (58) on the short stitch stop body (59) is performed by specifying a stop of a drive body (55) of the short stitch switchover drive (56) on the short stitch stop body (59).
12. Adjusting device according to any one of claims 1 to 11, characterised by a calibrating device (45) for adjusting a length ratio between a forward stitch length and a backward stitch length.
13. Sewing machine (1) with a stitch length-adjusting device (25) according to any one of claims 1 to 12.

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