Sewing – Elements – Thread cutting – severing or breaking
Reexamination Certificate
2003-03-10
2004-11-16
Izaguirre, Ismael (Department: 3765)
Sewing
Elements
Thread cutting, severing or breaking
Reexamination Certificate
active
06817306
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thread cutting device for sewing machine used when a sewing operation is performed while inserting an elastic cord in a circular part of a sewing object such as a waist part of underwear.
2. Description of the Background Art
Referring to
FIG. 10
, for example, in the case that the operator performs a sewing operation while inserting an elastic cord into a waist part (circular part)
51
of a sewing object
50
, such as underwear, by using a multi-needle sewing machine, the operator performs the sewing operation while moving the waist part
51
in a direction indicated by arrow A, in the state that the edge of a looper thread is held by a looper thread end holder disposed in the inside of a sewing bed. As the result, a plurality of seams
52
are formed throughout the periphery of the waist part
51
.
In this sewing operation, at the completion of the sewing throughout the periphery of the waist part
51
, the looper thread is hung on a thread guard part disposed at the tip of a movable thread guard member moved to the underside of an needle location. With the retraction of the movable thread guard member in this state to a side orthogonal to a sewing direction with respect to the needle location, the looper thread hung on the thread guard part is pulled into a preset position and then cut at this setting position by mutually contact action between the movable thread guard member and a stationary blade member, and the vicinity of a cutting edge of the looper thread is nipped between the movable thread guard member and a thread nip member in the looper thread end holder, then entering the state of waiting for the next following sewing operation.
In the sewing machine provided with the above-mentioned thread cutting device, a looper thread end
52
c,
so-called “fluff,” remains (normally, as long as about 5 cm to 7 cm) at a starting position
52
a
of the seams
52
, because the next sewing operation is started in the state that the vicinity of a cut end of the looper thread is nipped between the movable thread guard member and thread nip member. In order to eliminate such a long looper thread end
52
c,
i.e., fluff, the operation must cut off by manual operation with scissors etc every time the sewing operation is completed. This manual operation is time consuming, thereby lowering the sewing efficiency and increasing the sewing cost. In addition, there is the problem of imposing on the operator the serious burden if the operator continuously sews a large number of sewing objects one after another.
It can be considered that in order to omit the operation of fluff removal, part of the remaining long looper thread end
52
c
is sewed into the seams
52
in the following manner that the staring position
52
a
and a termination position
52
b
of the seams
52
are sewed one over the other. However, in this manner, the looper thread end
52
c
is extremely unstable and likely to drift during the time of sewing, failing to exactly match the seams
52
. This produces a poor finish on the sewing product, leading to non-conforming article. Consequently, the fluff is usually removed by manual cutting that is time consuming and imposes on the operator the serious burden.
As means for omitting such fluff removal by manual cutting, there have been proposed the followings.
Firstly, in a device disclosed in Japanese Patent Publication No. 7-34838 (hereinafter referred to as “device X”, concurrently with, alternatively, immediately after a sewing operation is started in the state that the vicinity of a cut end of a looper thread is nipped by a movable thread guard member and a thread nip member that constitute a lower thread (looper thread) retainer, the cut end of a looper thread is pulled into seams so as to reduce the edge length of the looper thread projecting from the starting position of the seams in the following manner that a stationary blade member and thread nip member are further retracted in a direction in which they depart from a setting position retracted to a side of a needle location with respect to the needle location, in order to release the nipping of the looper thread cut end by the movable thread guard member and thread nip member.
Secondly, in a device disclosed in Japanese Patent Unexamined Publication No. 1-290571 (hereinafter referred to as “device Y”), concurrently with, alternatively, immediately after a sewing operation is started, a cut end of a looper thread is pulled into seams and the edge length of the looper thread projecting from the starting position of the seams is reduced in the manner that a movable thread guard member is allowed to approach a needle location side by a predetermined amount in order to release nipping of the looper thread cut end by the movable thread guard member and a thread nip member.
With a conventional thread cutting device for sewing machine having the construction as shown in device X or device Y, the fluff removal by manual cutting can be omitted by reducing the length of the looper thread end projecting and extending from the starting position of the seams. However, to device X, in addition to the functions required for a thread cutting device, such as the cutting of a looper thread when a sewing operation is completed; and the nipping of a looper thread end so cut, in preparation for the next following sewing operation, it is necessary to add the following special functions that the nipping of the cut end of the looper thread is released concurrently with or immediately after the sewing operation is started, and that in order to apply tension to the cut end and pull the edge of the looper thread into the seams, the stationary blade member and thread nip member are further retracted in a direction in which they depart from their respective setting positions with respect to the needle location, while the movable thread guard member is maintained in its setting position. It is therefore necessary to convert an existing thread cutting device throughout its structure, thereby complicating the structure and increasing the cost of the device.
In device Y, an existing thread cutting device can be used as it is. Further, the structure of device Y is simpler than that of device X, and it is easy to reduce the cost. It is however necessary to add to the existing thread cutting device such a construction that only the movable thread guard member is moved so as to approach the needle location side by a predetermined amount while the stationary blade member and thread nip member are maintained at their setting positions. Therefore, an increase in the cost of the device is unavoidable.
Additionally, the conventional thread cutting devices, such as device X and device Y, are of the type in which the nipping of the cut end of the looper thread is released at a position away from the side of the needle location, in order to pull the cut end into the seams. It is therefore unavoidable that a looper thread having a considerable length (i.e., fluff) remains and projects beyond the starting position of the seams, although no manual cutting may be required. A further reduction in the length of the remaining thread is therefore desired in the case of quality sewing product, and depending on the type of the sewing product.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a thread cutting device for sewing machine that can considerably reduce the length of a looper thread end remaining at a starting position of seams merely by adding a very simple construction to an existing thread cutting device.
According to a first aspect of the present invention, in a thread cutting device for sewing machine including a thread cutting device that immediately after a sewing operation is completed, cuts a looper thread after pulling it into a setting position located at a side orthogonal to a sewing direction with respect to a needle location of a throat plate, there is provided a nip means for temporally nipping and holding a cut end of the looper t
Hochberg D. Peter
Izaguirre Ismael
Mellino Sean
Vieyra Katherine R.
Yamato Sewing Machine Seizo Co., Ltd.
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