Sewing – Stitch forming – Feeding work material
Patent
1990-05-04
1992-04-21
Schroeder, Werner H.
Sewing
Stitch forming
Feeding work material
112318, 1122627, 11212113, 112316, D05B 2714, D05B 6918
Patent
active
051057514
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention pertains in general to a sewing operation with a sewing machine driving both a needle, and an upper and/or lower feed means for feeding the fabric to be sewn, and specifically to a sewing operation for forming satisfactory initial stitches.
BACKGROUND OF THE INVENTION
In a sewing machine equipped with a needle oscillating in the direction of feed, the needle plate has a stitch hole designed as a slot. This stitch slot extends in the direction of feed. As a consequence of this, the interlock of the initial stitches, especially of the first stitch, will come undone due to the lack of friction between the threads at the edge of the stitch slot on the pulling by the thread lever, and satisfactory stitches will be prevented from forming. This happens mainly in the case of short thread ends after a thread cutting operation.
SUMMARY AND OBJECTS OF THE INVENTION
The object of the present invention is to provide a process in a sewing machine with needle feed which guarantees reliable stitch formation at the beginning of a new sewing operation.
This is accomplished in a process where the needle is displaced into an end zone of the stitch hole of the needle plate prior to the sewing operation. A preselected number of initial stitches are then formed in this position of the needle. The displacement of the needle is then abolished, and the feed motion of the fabric being sewn is corrected by the amount of the displacement.
The process according to the present invention makes it possible to substantially improve conditions for stitch formation at the very beginning of the seam formation by the sufficient clamping effect of the threads at the edge of the stitch slot and thereby to achieve reliable initial stitch formation.
An advantageous feature of the invention is that during the initial stitches, the needle can perform a feed motion corresponding to the feed motion of the fabric. The feed motion of the fabric being brought about by upper and lower feed means.
The process according to the invention can also be designed so that the needle is stopped in its displaced position during the initial stitching and the entire feed motion of the fabric is performed by the feed means only during the phase in which the needle is withdrawn from the fabric. After the axis of the needle returns to its normal position, the needle can be moved allowing feeding for the fabric both when the needle has penetrated the fabric and when it has been withdrawn. This feature allows both the entry and the exit of the needle into and from the fabric being sewn to take place in the immediate end zone of the stitch slot. As a result of which optimal clamping conditions are created for the free thread ends at the edge of the stitch slot.
It is also possible to have the feed motion turned off during the first stitch, causing a reduction of thread consumption during the first stitch formation and consequently a reduction of after pulling of the sewing threads through the thread lever.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which a preferred embodiment of the invention is illustrated.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is a synoptic, partially cut-away view of a sewing machine equipped with a needle feed mechanism;
FIG. 2 is an enlarged, partially cut-away side view of the sewing machine according to FIG. 1;
FIG. 3 is a sectional view along line III--III in FIG. 2;
FIG. 4 is a partially cut-away rear view of the stepping motor drive for swinging out the needle bar;
FIG. 5 is a block diagram of the electronic circuitry for the feed mechanism;
FIG. 6 is an enlarged sectional view through the needle plate of the sewing machine;
FIG. 7 is an enlarged detail from FIG. 4;
FIG.
REFERENCES:
patent: 2669206 (1954-02-01), Pinkvoss et al.
patent: 3216386 (1965-11-01), Bono
patent: 4182252 (1980-01-01), Yoneji et al.
patent: 4513676 (1985-04-01), Martell et al.
patent: 4643118 (1987-02-01), Bungert et al.
patent: 4671197 (1987-06-01), Bungert et al.
patent: 4860677 (1989-08-01), Ishihara
Balzer Dieter
Bungert Heinrich
Ulmen Mathias
Izaguirre Ismael
Pfaff Industriemaschinen GmbH
Schroeder Werner H.
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