Sewing – Elements – Thread cutting – severing or breaking
Reexamination Certificate
2000-11-28
2001-11-20
Izaguirre, Ismael (Department: 3765)
Sewing
Elements
Thread cutting, severing or breaking
Reexamination Certificate
active
06318282
ABSTRACT:
BACKGROUND OF INVENTION
The present invention relates to a thread trimming device in a sewing machine, particularly to a thread trimming device for capturing and cutting a spreader thread in a sewing machine, which is also capable of blowing the needle thread cut off by the under trimming mechanism away from the underside of the presser foot after the presser foot is lifted at the end of a sewing operation in order to facilitate the next sewing operation.
DESCRIPTION OF PRIOR ART
In order to increase the sewing speed and to improve the convenience for users, an industrial sewing machines is usually installed with an automatic thread trimming device. For spreader threads, there are specific thread trimming devices, such as disclosed in ROC (Taiwan) Publication No. 71925 “Device for cutting a cover thread in a multi-needle sewing machine”. Such a conventional device for cutting a spreader thread (cover thread) usually has a complex structure with large dimensions; moreover, when not using a spreader thread trimmer (for example, when sewing without a spreader thread), an additional blowing means is further required for blowing away the free end of the needle thread cut off by the under trimming mechanism in order to facilitate the next sewing operation, which not only increases the complexity and the difficulty in operation but also substantially raises the cost for manufacture and maintenance. Therefore, it has become a task to provide a device for trimming a spreader thread when sewing with a spreader thread and for blowing away the free end of the needle thread cut off by the under trimming mechanism when sewing without a spreader thread.
SUMMARY OF INVENTION
The object of the present invention is to provide a thread trimming device for a spreader thread, which is capable of not only cutting off a spreader thread, but also blowing away the free end of the needle thread cut off by the under trimming mechanism.
Another object of the present invention is to provide a thread trimming device for a spreader thread, which has a simple structure and is easily manufactured and maintained.
A further object of the present invention is to overcome the drawback of a conventional sewing machine having separate spreader tread trimmer and blowing means, and to provide a spreader thread trimming device which can be used to cut off a spreader thread when sewing with a spreader thread and to blow away the needle thread when sewing without a spreader thread.
The present invention comprises an air cylinder which is driven by compressed air. When sewing with a spreader thread, the air cylinder drives a movable catcher and a fixed cutter to cut off a spreader thread, which is then clamped by a spring plate to facilitate the next sewing operation. When sewing without a spreader thread, compressed air is used through an air passage to blow the free end of the needle thread cut off by an under trimming mechanism away from the underside of the presser foot after the presser foot is lifted at the end of a sewing operation to facilitate the next sewing operation. The air cylinder in the present invention may also be replaced by an electromagnetic relay, which, when powered up, stretches and retracts the central shaft to drive a movable catcher and a fixed cutter and thereby cut off the spreader thread.
REFERENCES:
patent: 3901171 (1975-08-01), Rosa
patent: 4436044 (1984-03-01), Nordstrom et al.
patent: 4550672 (1985-11-01), Kastrup
patent: 5127350 (1992-07-01), Okada et al.
patent: 71925 (1985-11-01), None
Izaguirre Ismael
Kaulin Mfg. Co., Ltd.
LandOfFree
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