TW201920796A - Method of operating a sewing machine and sewing machine adapted to carry out the method - Google Patents

Abstract

In the operation of a sewing machine, at least one seam is sewn in a piece of fabric. At the same time, a feed unit of the piece of fabric is driven in a fabric feed direction (2) by means of a fabric feed drive mechanism (8). While the seam is being sewn, a needle feed unit (18) of the sewing machine (3) is operated in such a way that a needle (4, 5) feeds the piece of fabric counter to the fabric feed direction (2) while a respective stitch is being made. As a result, an operating method and a sewing machine operating therewith are obtained which allow an improved seam pattern to be produced.

Description

Method for operating sewing machine and sewing machine configured to perform said method

FIELD OF THE INVENTION The present invention relates to a method of operating a sewing machine. The invention also relates to a sewing machine configured to perform the method.

BACKGROUND OF THE INVENTION A method for operating a sewing machine is known from EP 3 088 589 A1 and DE 100 22 237 B4. Document DE 10 2011 100 103 A1 describes a sewing machine with a needle feed unit to change the step size. German Patent No. 1 485 148 describes a sewing machine with a needle feeder, in which a corresponding feeding tool is provided to add an additional layer of sleeve fabric required for embedding the sleeve. Document DE 34 11 217 A1 describes a double-chain sewing machine with a shuttle drive mechanism that can be driven to set the absolute amount of fabric feed or the swinging motion of the sewing needle. Document DE 10 2007 004 549 A1 describes a feed adjustment device for a sewing machine. German patent No. 868 832 describes a feeding device for a sewing machine. Document DE 33 42 391 C1 describes a sewing machine with a needle feed unit and a bottom feed mechanism.

SUMMARY OF THE INVENTION The object of the present invention is to further develop a sewing machine of the type mentioned at the beginning, so that the seam pattern is improved.

According to the invention, this object is achieved by an operating method for a sewing machine, which method comprises the steps of sewing at least one seam in a fabric sheet while simultaneously feeding the fabric feed direction in the fabric feed direction using a fabric feed drive mechanism Fabric pieces, and the needle feed unit of a sewing machine operated when a seam is sewn, so that the needles feed the fabric pieces in the opposite direction to the fabric feed direction when the corresponding stitches are manufactured.

Surprisingly, it has been found that, depending on the fabric quality and fabric thickness, and according to the sewing thread parameters, if the needle feed unit for feeding a fabric piece is operated in a direction opposite to the fabric feed direction of the additional fabric feed drive mechanism, The seam pattern is improved. Although it is expected that this "reverse operation" of the needle feed unit and the fabric feed driving mechanism will cause a poor seam pattern, in fact, this reverse operation according to the type of fabric and the type of sewing thread can be reproduced reproducibly Improved seam patterns.

The adjustable phase relationship of the fabric feed drive with respect to the needle feed unit allows fine adjustment of the reverse operation between the periodic operation sequence of the fabric feed drive and the needle feed unit, which can be used to optimize the seam pattern. One cycle of the corresponding operation sequence of the fabric feed driving mechanism and the needle feed unit may coincide with the cycle of the sewing machine to form exactly one stitch.

The advantages of fine-tuning the operating sequence are particularly applicable to the phase relationship adjustment performed when sewing a seam. For example, the first phase relationship between the periodic operation sequence of the fabric feed driving mechanism and the needle feed unit may exist at the beginning of the seam to be sewn, and this type of different phase relationship may exist at the end of the seam Office. This phase relationship adjustment allows the sewing machine to adapt to different sewing conditions during seam formation.

The step length relationship has proven to be particularly suitable for improving the seam pattern, which makes the stitch feeding step of feeding the fabric piece by means of the needle feeding unit while the stitches are performed, smaller in absolute value than the stitches used in manufacturing the stitch At the same time, the feed step of the fabric sheet is fed by means of a fabric feed driver. The absolute relationship between the needle feed step and the fabric feed step can be in the range of 1/10 to 2/1. In reverse operation, the absolute needle feed step can also be larger than the fabric feed step.

The advantages of a sewing machine configured to perform the method according to the invention correspond to those described above with reference to the method of operation. The sewing machine can be a single-needle sewing machine or a double-needle sewing machine.

A fabric feed driver configured as a fabric clamp allows independent actuation of the fabric feed in the fabric feed unit relative to the actuation of the needle feed unit. Alternatively, the fabric feeding driving mechanism may also be configured to include a top feeding unit including at least one top feeding device and / or a bottom feeding unit including at least one bottom feeding device. The fabric feed driving mechanism is capable of feeding the fabric sheet to be sewn by frictional contact with the fabric sheet during the formation of the seam.

The stepper motor of the needle feed unit allows precise setting of the needle feed step size, which acts on the adjustment shaft to adjust the needle feed step size, which can be changed in small incremental increments, especially almost continuously Variety.

A control unit configured to define a phase relationship between the fabric feed driving mechanism and the needle feeding unit allows flexible setting of a reverse operation between the fabric feeding driving mechanism and the needle feeding unit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a partial schematic view of the main components of a sewing unit 1 which is particularly used, for example, to produce bags with pocket openings, which are trimmed by piping. The sewing unit 1 can be used to sew an additional fabric portion such as a piping to a basic fabric portion such as a pants portion or a blazer portion. The sewing unit can also be used to sew covered pockets or welt pockets.

When the seam is sewn into the fabric sheet, the fabric sheet is simultaneously fed in the fabric feed direction 2 (hereinafter also referred to as the sewing direction) in a driven manner. The sewing direction 2 extends along the x direction of the Cartesian xyz coordinate system included in FIG. 1.

The sewing unit 1 has a sewing machine 3 adapted to sew a fabric piece, and the sewing machine 3 is configured as a two-needle sewing machine including sewing needles 4, 5 (see, for example, FIG. 2). When viewed in the sewing direction 2, the piping or cover is folded and the feeding device is arranged upstream of the sewing needles 4, 5, in other words, offset in the negative x direction. The general operating mode of the hemming feed device is known from the prior art. More information on this can be found in the previously published documents DE 100 16 410 C1, DE 199 26 866 C1 and DE 198 45 624 C1 and the references cited there.

The fabric piece is located on a support plate 7 of the sewing machine 1. The support plate 7 defines a support plane parallel to the xy plane.

The driven fabric gripper 8 of the fabric feed drive mechanism, which is only drawn by dashed lines and is generally known from document EP 3 088 589 A in the schematic diagram according to FIG. 1, is used to press the fabric sheet against the corresponding seam to be produced. The fabric sheet is fed on a support plate 7 on the side and in the sewing direction 2. The sewing machine 3 allows an additional needle feed unit to be optionally activated, for example temporarily activated.

An operable display of the sewing unit 1 that can be configured as a touch screen is provided to the user to select a sewing program, enter sewing data, and monitor the sewing process. An unshown display is actuated via a central control unit 9 shown in the schematic diagram in FIG. 1.

The fabric jig 8 including the jig frame is covered with a cover cover 10.

The sewing unit 1 has a main frame 11 which carries a sewing machine 3 and a fabric feed conveying member configured to feed a fabric sheet to a stitch formation region and a fabric discharge member configured to eject the fabric sheet from the stitch formation region. The main frame 11 includes a support plate 7. The sliding plate 12 of the sewing unit 1 is mounted in the region of the support plate 7. During the feeding, the fabric sheet slides along the sliding plate 12.

2 to 7 show details of a needle feeding unit 18 for generating a needle feeding movement, the needle feeding unit 18 being configured such that the sewing needles 4, 5 entering the fabric piece are in the sewing direction 2 or the sewing direction 2 Conversely, the fabric piece is fed or the sewing needles 4, 5 entering the fabric piece have no fabric feed function. 2 and 3 show the needle feeding unit 18 in the setting position "needle feeding in the sewing direction 2", in other words, in the positive x direction. The setting positions shown in FIGS. 4 and 5 are such that the needle feeding unit 18 is configured to perform a needle feeding motion opposite to the sewing direction 2, in other words, in the negative x direction. In the setting position of the needle feeding unit 18 shown in Figs. 6 and 7, the sewing needles 4, 5 have no fabric feeding function.

The needle feed driver originates from an arm shaft 19 which extends in the arm 20 (see FIG. 2) of the sewing machine 3. At the free end, the arm shaft 19 is non-rotatably connected to a manually operable hand wheel 21.

The arm shaft 19 acts on the needle feed adjustment gear mechanism 23 via the eccentric 22. The adjustment gear mechanism 23 is configured as a tongue gear mechanism.

In the sewing operation, the arm shaft 19 is driven by a drive motor, which is not shown in the figure, and can be accommodated in, for example, the bracket 24 or the main frame 11 below the support plate 7 of the sewing machine 3.

The adjustment gear mechanism 23 generates a swinging motion of the output lever 25 of the needle feeding unit 18. Both the swing angle and swing width of the output lever 25 are determined in advance by the corresponding gear settings of the adjustment gear mechanism 23. The gear setting is performed by rotating an adjustment shaft configured as a gear shaft 26 that interacts with the adjustment gear mechanism 23 and also extends parallel to the arm shaft 19. Accordingly, the corresponding angular setting of the gear shaft 26 causes different feed strokes of the needle feed unit in the sewing direction 2.

The angle setting of the gear shaft 26 can be changed by means of a needle feed switching device 27 which is configured as an actuator in the form of a stepper motor. The stepper motor is rigidly connected to the frame of the sewing machine 3 via a frame latch 28 in a manner not shown in more detail. The motor shaft 29 of the stepping motor 27 is connected to the gear shaft 26 via a lever driving mechanism 30. The frame of the adjustment gear mechanism 23, the output lever member 31 of the lever driving mechanism 30, and the gear shaft 26 are non-rotatably connected to each other. The swing motion of the motor shaft 29 from the neutral position in FIGS. 6 and 7 is +/- 30 ° to reach the maximum “forward needle feed” according to FIGS. 2 and 3 and the maximum “back needle” according to 4 and 5 Feed "positions.

The stepping motor 27 performs signal communication with the central control unit 9 of the sewing unit 1. The control unit 9 is used to actuate, for example, a fabric feed driving mechanism via a fabric clamp 8, a stepper motor of the needle feed switching device 27, and a drive motor for the arm shaft 19.

As shown in FIGS. 2 to 7, the needle feeding unit 18 can be “needle fed in the sewing direction 2” (see FIG. 2/3) and “needle fed in the opposite direction to the sewing direction 2” by means of the needle feeding switching device 27. "(See Fig. 4/5) and" Neutral position without needle feed function "(see Fig. 6/7).

The output lever 25 transmits the swing amplitude defined by the adjustment gear mechanism 23 to the needle lever link shaft 36. Therefore, the swing amplitude of the needle bar link shaft 36 is defined by the swing amplitude of the output lever 25. The needle bar link shaft 36 also extends parallel to the arm shaft 19.

The needle bar link shaft 36 is non-rotatably connected to a needle bar link 37 for a needle bar 38 to which the two sewing needles 4, 5 are fixed by means of a needle holder 39.

The needles 4 and 5 perform a swing motion around the needle feed swing shaft 40 in response to the swing amplitude of the needle bar link shaft 36.

2 to 7 further show an arm shaft crank 42 for actuating the needle bar 38 in upward and downward directions, and a threaded rod 43 including a threaded rod adjustment element 44 with a support point.

When the sewing machine 3 is operated, the corresponding seams are sewn, and at the same time, the fabric pieces are fed in the sewing direction 2, that is, in the fabric feed direction, by means of a fabric feed drive mechanism, that is, driven by the fabric clamp 8 . When sewing the corresponding seam, the needle feed unit 18 is operated so that the needles 4 and 5 feed the fabric piece in the opposite direction to the fabric feed direction 2 when making the corresponding stitches. Therefore, during the sewing operation, the operation position of the needle feed unit 18 is either as shown in FIGS. 4 and 5 or an intermediate position defined by the corresponding step position of the stepper motor 27, which is located as shown in FIGS. Between the "Maximum Backward Needle Feed" position shown in 5 and the neutral position shown in Figures 6 and 7.

The stepper motor 27 allows almost continuous adjustment between the "maximum forward / backward needle feed" position shown in Fig. 2/3 and the neutral position shown in Fig. 6/7.

If the fabric feed driving mechanism, that is, the fabric clamp 8 has a periodic operation sequence when making stitches, the fabric feed driving mechanism 8 works with an adjustable phase relationship related to the needle feed unit 18 when making the corresponding stitches . By actuating the feed drive mechanism of the fabric clamp 8 via the control unit 9 accordingly, the phase relationship can be adjusted during the formation of the corresponding seams or even when the corresponding stitches are manufactured.

The fabric piece is fed by means of a needle feed unit 18 during the manufacture of the stitches along a needle feed step that can be adjusted via a stepper motor 27, which can be smaller in absolute value than by means of The feeding step of the fabric clamp 8 for feeding the fabric pieces. In general, the needle feed step may also be larger than the feed step in absolute value. The absolute step ratio of the needle feed step / feed step can be in the range of 1/10 to 2/1, especially in the range of 1/10 to 8/10, in the range of 2/10 to 7/10 Within the range of, for example, within the range of 3/10, within the range of 4/10, within the range of 5/10, or even within the range of 6/10. The fabric feed step can be in the range of 2.5mm. The absolute needle feed step in reverse operation can be in the range of 0.1mm to 3.5mm.

Instead of the fabric feed driving mechanism configured as a fabric clamp, the fabric feed driving mechanism may also be configured as a top feeding unit and / or a bottom feeding unit. From DE 196 03 294 C1, a feed jaw configured to provide a feed movement of the top of the fabric is known. From EP 2 330 241 B1, a feed tooth configured to provide a feed motion of the bottom of the fabric is known.

Adjusting the needle feed step size can be performed in a controlled manner, for example in response to detecting the fabric thickness. To this end, the control unit 9 can communicate with a fabric thickness sensor (not shown) and actuate the stepper motor 27 when a predetermined fabric thickness is reached. The needle feed can also be adjusted in response to the measured fabric feed speed. For this reason, during the sewing operation, the speed of the fabric feed is monitored, for example, using an optical sensor.

1‧‧‧ sewing unit

2‧‧‧ fabric feed direction; sewing direction

3‧‧‧ sewing machine

4, 5‧‧‧ sewing needles

7‧‧‧ support plate

8‧‧‧ fabric feed drive mechanism; fabric fixture

9‧‧‧ control unit

11‧‧‧ main frame

12‧‧‧ sliding board

18‧‧‧ Needle feed unit

19‧‧‧ arm shaft

20‧‧‧ arm

21‧‧‧Handwheel

22‧‧‧eccentric wheel

23‧‧‧adjusting gear mechanism

25‧‧‧output lever

26‧‧‧adjustment shaft; gear shaft

27‧‧‧ stepper motor; switching device

28‧‧‧Frame latch

29‧‧‧Motor shaft

30‧‧‧ Lever-driven mechanism

31‧‧‧Output lever parts

36‧‧‧ Needle bar connecting rod shaft

37‧‧‧ Needle bar connecting rod

38‧‧‧ Needle bar

39‧‧‧ Needle holder

40‧‧‧ swing axis

42‧‧‧arm shaft crank

43‧‧‧Threaded Rod

44‧‧‧Threaded rod adjustment element

x‧‧‧ direction

Exemplary embodiments of the present invention will be explained in more detail below with reference to the drawings, in which:

Figure 1 shows a perspective view of the main components of a sewing unit including a two-needle sewing machine;

2 and 3 respectively show perspective views of a needle feeding part assembly of the sewing machine, the needle feeding part assembly including a needle feeding driver and a setting part derived from an arm shaft in a "forward needle feeding" position;

Figures 4 and 5 show views of the needle feeding member assembly in a "backward needle feeding" position similar to Figures 2 and 3; and

Figures 6 and 7 show views of the needle feeding member assembly in a "neutral needle feeding" position similar to that of Figures 4 and 5.

Claims (8)

A method of operating a sewing machine, the method having the following steps: -Sew at least one seam in the fabric sheet, while using the fabric feed drive mechanism to feed the fabric sheet in the fabric feed direction; -Operate the needle feed unit of the sewing machine while sewing the seam so that the needle feeds the fabric piece in the opposite direction to the fabric feed direction when making the corresponding stitches. The method according to claim 1, wherein the fabric feed driving mechanism operates in an adjustable phase relationship with respect to the needle feed unit. The method according to claim 2, wherein the phase relationship is adjusted when sewing a seam. The method according to claim 1, characterized in that the step of feeding the fabric piece by means of a needle feeding unit by means of a needle feeding unit during the production of the stitches is, in absolute terms, smaller than the feeding by means of the fabric when the stitches are produced The feeding step of the fabric sheet by the driver. A sewing machine configured to perform the method as described in claim 1. The sewing machine according to claim 5, wherein the fabric feed driving mechanism is configured as a fabric clamp. The sewing machine according to claim 5, wherein the needle feeding unit has a stepping motor, and the stepping motor acts on the adjustment shaft to adjust the needle feeding step. The sewing machine according to claim 5, further comprising a control unit configured to define a phase relationship between the fabric feed driving mechanism and the needle feed unit.