Sewing machine

Abstract

A sewing machine has seam-forming tools, comprising a needle for guiding an upper thread and a looper. The needle is designed as a curved needle which is pivotable about a needle pivot axis. This embodiment is such that a distance of the curved needle from the pivot axis is equal to a radius of a curve of the curved needle about the pivot axis. The looper is designed as a looper which is rotatable about a looper rotational axis and has a lower thread reserve. The looper rotational axis runs parallel to a sewing material support region. The sewing machine can be used to produce a durable seam.

Claims

1. A sewing machine (1) having seam-forming tools (6), comprising a needle (7) for guiding an upper thread (8) and a looper (9), wherein the needle (7) is designed as a curved needle (7) which is pivotable about a needle pivot axis (10) in such a way that a distance (A) of the curved needle (7) from the pivot axis (10) is equal to a radius (r) of a curve of the curved needle (7) about the pivot axis (10), wherein the looper (9) is designed as a looper (9) which is rotatable about a looper rotational axis (15) and having a lower thread reserve (16), wherein the looper rotational axis (15) runs parallel to a sewing material support region (12), wherein an arrangement of the sewing material support region (11) with respect to a movement path (13) of the curved needle (7) is such that the curved needle (7), during a sewing movement along the movement path (13), penetrates into sewing material (4) to be sewn from a sewing material side (14) and exits again on the same sewing material side (14), having a design such that the sewing material is sewn in the form of an abutting-edge sewing using a single-sided double lockstitch.

2. The sewing machine according to claim 1, wherein the needle pivot axis (10) runs parallel to the looper rotational axis (15).

3. The sewing machine according to claim 1, wherein the lower thread reserve (16) is designed as a bobbin case accommodated in or at the looper (9) for a lower thread winding.

4. The sewing machine according to claim 1, comprising a design for sewing material thicknesses (D) greater than 8 mm.

5. The sewing machine according to claim 1, comprising a belt drive (18) for driving the curved needle (7) and the looper (9).

6. The sewing machine according to claim 1, wherein the curved needle (7) has a guide groove (39) arranged helically around the curved needle (7), over which the upper thread (8) is guided.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0018] FIG. 1 shows a schematic view of stitch-forming and drive components of a sewing machine upon abutting-edge sewing of two adjacent pieces of sewing material; and

[0019] FIG. 2 in an illustration similar to FIG. 1, shows a view of upper thread guide components of the sewing machine.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0020] A sewing machine 1, of which drive and stitch-forming components are shown in FIG. 1 and upper-thread guide components are shown in FIG. 2, serves for abutting-edge sewing of two pieces 2, 3 of sewing material 4 placed end to end. The sewing machine 1 as a whole is designed as a hand sewing machine, i.e. it is not permanently installed for stationary operation and can be held in the hand by an operator during the sewing process. In particular, the sewing machine 1 can be designed without supply lines which are connected to an external supply unit.

[0021] The two pieces 2, 3 of the sewing material 4 butt against each other via an abutting edge 5. The sewing machine 1 is designed to sew sewing material 4 having a material thickness D which is greater than 8 mm. The sewing material 4 can have a material thickness in the range between 10 mm and 25 mm, for example.

[0022] Seam-forming tools 6 of the sewing machine 1 include a needle 7 for guiding an upper thread 8 (cf. also FIG. 2) and a looper 9.

[0023] The needle 7 is designed as a curved needle. The curved needle 7 can be pivoted about a needle pivot axis 10. A distance A between the curved needle 7 and the needle pivot axis 10 is equal to a radius r of a curve of the curved needle 7 about the needle pivot axis 10.

[0024] A stitch plate 12 belongs to a sewing material support region 11, which specifies a position of the sewing material 4 relative to the seam-forming tools 6 upon abutting-edge sewing.

[0025] The sewing material support region 11 is arranged in relation to a movement path 13 of the curved needle 7, which is indicated by a dashed line in FIG. 1, in such a way that during the sewing movement along the movement path 13, the curved needle 7 penetrates into the sewing material 4 to be sewn from a sewing material side 14, which points upward in FIGS. 1 and 2, and exits again on the same sewing material side 14. This entry/exit sewing material side 14 faces the looper 9. The curved needle does not come out of the sewing material 4 on the sewing material side opposite this entry/exit sewing material side 14.

[0026] The looper 9 is rotatable about a looper rotational axis 15 and has a lower thread reserve in the form of a bobbin case 16. The stitch plate 12 has a case stop piece 17 for preventing rotation of the bobbin case about the looper rotational axis 15.

[0027] The looper rotational axis 15 runs parallel to the needle pivot axis 10. Both axes 10, 15 run horizontally and perpendicularly to the drawing plane in FIGS. 1 and 2.

[0028] The looper rotational axis 15 runs parallel to the sewing material support region 11.

[0029] A belt drive 18 having a drive motor 19, which may be an electric motor having a battery supply, and a belt 20 are used to drive the curved needle 7 and the looper 9. The belt 20 is driven via a drive shaft 21 of the drive motor 19 and runs over a main shaft 22, a thread lever eccentric 23, a tension roller 24 and a looper shaft which runs along the looper rotational axis 15.

[0030] Via a further eccentric 25, the main shaft 22 is pivotally connected to a swing lever 26, which in turn is eccentrically pivotally connected to a needle drive shaft 28 via a needle drive wheel 27. Via a further belt 29, the needle drive wheel 27 is connected to a needle shaft which runs along the needle pivot axis 10. The shafts 21, 22 and 28 again run parallel to the needle pivot axis 10 and to the looper rotational axis 15. The belt drive with the belts 20, 29 is designed in such a way that the looper 9 rotates twice during a movement period of the curved needle 7. Via the swing lever 26 and the further belt 29, an oscillating drive of the curved needle 7 about the needle pivot axis 10 is achieved, which is synchronized with the rotation of the looper 9 about the looper rotational axis 15. The sewing machine 1 generates a double lockstitch in the sewing material 4 via the seam-forming tools 7, 9 and the belt drive 18 for abutting-edge sewing and thus for durably joining the two pieces 2, 3 of the sewing material 4.

[0031] The tension roller 24 is pretensioned against the belt 20 by a tensioning spring and provides sufficient tension to the belt 20. The belt 29 may also have a tension roller not shown in the drawing.

[0032] The movement of the curved needle along the movement path 13 is guided by a frame-fixed curve guide 30. The curved needle 7 is connected to the needle shaft by a needle holder 31.

[0033] A thread lever 32 of the sewing machine is driven via the thread lever eccentric 23. The thread lever 32 has a thread lever arm 33.

[0034] FIG. 2 additionally shows upper thread guide components of the sewing machine 1. The upper thread 8 is fed via an upper thread reserve in the form of a thread reel 34. From there, the upper thread 8 first runs over a thread pre-tensioning unit 35 and a thread deflection eyelet 36. From there, the upper thread 8 runs over a thread lever eyelet 37 and another thread deflection eyelet 38 to a guide groove 39, which is arranged helically in a jacket wall of the curved needle 7. At this free end, the curved needle 7 has an eye 40.

[0035] A plane of the movement path 13, which runs parallel to the drawing plane of FIG. 1, is offset perpendicularly to the drawing plane of FIG. 1 with respect to a movement path of a looper tip 41 of the looper, so that the looper tip 41 can run past a needle tip of the curved needle 7 when gripping an upper thread loop upon stitch formation. The needle tip of the curved needle 7 having the eye 40 passes through a stitch hole 42 in the stitch plate 12.

[0036] As far as possible, the seam-forming tools 6 and the upper thread guide components are accommodated in a housing 43 of the sewing machine 1 (cf. FIG. 2).