Sewing – Elements – Thread cutting – severing or breaking
Reexamination Certificate
2000-04-10
2001-07-24
Izaguirre, Ismael (Department: 3741)
Sewing
Elements
Thread cutting, severing or breaking
Reexamination Certificate
active
06263813
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for preventing a stitching from raveling from the sewn end side on forming a double chain stitch in a cloth by a sewing machine.
2. Description of the Prior Art
This kind of stitching ravel preventing device is used in a sewing machine having at least one needle moving vertically, and a looper oscillating almost horizontally between the forward position and backward position across the needle, in which the double chain stitch is formed in the cloth after a thread triangle is formed by a loop-shaped needle thread consecutive to the needle via the looper from the cloth and a looper thread along the looper via the looper eyelet from the cloth by collaboration of the needle and looper.
By this sewing machine, when a stitch, for example, JISL0120 stitch type 406, is formed, if the looper thread is pulled from the sewn end side of the stitching, the stitching is raveled out. As an apparatus for preventing a stitching from raveling, it is disclosed in Japanese Laid-open Patent No. 9-225163 that the construction comprises such a sewing machine, looper thread engaging means, a looper thread cutter and a thread cutter.
A looper thread engaging means forms a looper thread loop consecutively from the cloth at the engaged portion by driving the sewing machine in a state engaged within the longer thread consecutive to the looper from the cloth by moving when the looper is located at the forward position. The looper thread cutter cuts off the looper thread loop at the engaged portion. The thread cutter cuts off the loop-shaped needle thread consecutive to the needle via the looper from the cloth and the looper thread consecutive to the looper from the cloth between the cloth and the looper
According to such a construction, when nearing the finish of sewing on the double chain stitch formed in the cloth, it makes the looper thread engaging means engage with the looper thread consecutive to the looper from the cloth. In this state, the sewing machine is driven for one stitch, and the looper thread loop consecutive from the cloth is formed at the engaged portion, and then the looper thread loop at the engaged portion is cut off, and afterward, or at the same time, the loop-shaped needle thread consecutive to the needle through the looper from the cloth and the looper thread consecutive to the looper from the cloth are cut off between the cloth and the looper.
In such a conventional ravel preventing method, however, since the moving distance of the looper thread engaging means cannot be defined, the length of the looper thread loop formed by the looper thread engaging means cannot be changed, and therefore the length of the thread end left over in the cloth by the looper thread cutter could not be changed.
SUMMARY OF THE INVENTION
The present invention is provided in light of the above-mentioned background, and it is hence an object of the present invention to provide an apparatus capable of preventing a stitching from raveling from the sewn end side on forming a double chain stitch in a cloth by a sewing machine, and obtaining a good-looking sewn product by varying the length of thread end consecutive to the sewn end side.
To achieve the object, the apparatus for preventing a stitching from raveling of the present invention comprises a sewing machine having at least one needle (
5
,
6
) moving vertically and a looper (
3
) for forming a double chain stitch (S) made up of needle threads (
8
,
9
) and looper thread (
10
) in a cloth (W) by collaboration with the needle by oscillating almost horizontally between the forward position and backward position across the needle (
5
,
6
), looper thread engaging means (
11
) for forming a looper thread loop (
10
L) consecutive from the cloth (W) at its engaged portion by driving the sewing machine in an engaged state by engaging with the looper thread (
10
) consecutive to the looper (
3
) from the cloth (W) by moving when the looper (
3
) is at the forward position, a looper thread cutter (
12
) for cutting the looper thread loop (
10
L) at the engaged portion, and a thread cutter (
30
) for cutting loop-shaped needle threads (
8
L,
9
L) consecutive to the needles (
5
,
6
) via the looper (
3
) from the cloth (W) and the looper thread (
10
) consecutive to the looper (
3
) from the cloth (W) between the cloth (W) and the looper (
3
), in which defining means (
27
) is further provided to define the moving distance of the looper thread engaging means (
11
), and the length of the looper thread loop (
10
L) is changed by definition of moving distance of the looper thread engaging means (
11
) by the defining means (
27
), and therefore the length of the thread end left over in the cloth (W) by the looper thread cutter (
12
) can be varied.
According to the present invention having the above-mentioned characteristic construction, when the looper is at the forward position near the sewing finish on the double chain stitch formed in the cloth by the sewing machine, the looper thread engaging means is moved and is engaged with the looper thread consecutive to the looper from the cloth. The moving distance of the looper thread engaging means is defined by the defining means. In this engaged state, by driving the sewing machine, a looper thread loop consecutive from the cloth is formed at the engaged portion of the looper thread engaging means. The length of the looper thread loop is defined by changing the engaged state with the looper thread engaging means by the defining means. The looper thread loop at the engaged portion by the looper thread engaging means is cut off by the looper
In the apparatus having such a construction, the looper thread engaging means includes at least a looper thread engaging member and a driving member for moving the looper thread engaging member to the engagement position of the looper thread, and the defining means is composed of a stopper piece for defining the moving distance of the driving member. When the looper thread engaging member is moved by the driving member and is engaged with the looper thread consecutive to the looper from the cloth, its moving distance is defined by the stopper piece.
Also, in the apparatus having such a construction, the looper thread engaging member has a taper portion and two crooks protruding nearly at the middle position and tip position of the taper portion. When a position of the looper thread engagement with the taper portion across the crook at the middle position can be changed depending on the definition of the moving distance of the driving member by the stopper piece, the crook can be easily engaged with the looper thread consecutive to the looper from the cloth. In addition, the looper thread loop can be cut off by the looper thread cutter securely at the corresponding crook.
Moreover, the stopper piece is a rectangular block fixed in the sewing machine so as to be variable in angle and the definition of the moving distance in the driving member is done by varying the fixing angle of the rectangular block in the sewing machine, the moving distance of the driving member can be defined in a simple construction.
Other objects and effects of the present invention will be better understood from the following detailed description of the embodiments.
REFERENCES:
patent: 1284911 (1918-11-01), Lautenschlager
patent: 4169422 (1979-10-01), Hayes et al.
patent: 5722338 (1998-03-01), Douyasu
patent: 5881663 (1999-03-01), Tsukioka et al.
patent: 6119613 (2000-09-01), Douyasu et al.
Nakano Kazuyuki
Toume Fumio
Watanabe Masashi
Izaguirre Ismael
Jones Tullar & Cooper P.C.
Pegasus Sewing Machines Mfg. Co., Ltd.
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