Double chainstitch sewing machine

Details Double chainstitch sewing machine Double chainstitch sewing machine

2001-08-06

2002-05-21

Nerbun, Peter (Department: 3765)

Sewing

Stitch forming

Multiple needle

C112S249000

Reexamination Certificate

active

06390000

ABSTRACT:

The present invention relates to a double chainstitch sewing machine for forming stitches for applying a cover thread at the lower side or upper and lower sides of a workpiece.
BACKGROUND OF THE INVENTION
FIG. 11
shows a double chainstitch sewing machine for forming stitches related to stitch type number 407 and others designated in the United States Federal Standards No. 751a.
In this sewing machine, the needle thread is first passed from a thread tension device
117
into a thread eye of a first thread take-up
116
through a fixed thread guide
114
. In succession, the needle thread is passed into a thread eye of a movable thread guide
115
through a U-shaped second thread take-up
118
, and is passed into an eyelet of a needle holder
120
at the lower end of a needle bar
112
and an eyelet of a needle
119
.
When forming stitches for applying a cover thread at the upper and lower sides of a workpiece by this double chainstitch sewing machine, an upper cover thread mechanism disclosed in Japanese Utility Model 63-26144 is disposed beneath a sewing machine head
111
a.
The upper cover thread is supplied into the upper cover thread mechanism by way of a thread take-up for upper cover thread (not shown) provided in the first thread take-up
116
from the thread tension device
117
.
The movable thread guide
115
is affixed to the upper end of the needle bar
112
, and moves up and down together with the needle bar. The first thread take-up
116
is affixed to an oscillating shaft
113
, and oscillates about the shaft. All these members move up and down or oscillate outside of the sewing machine arm
111
and are hence dangerous. Accordingly, to protect the operator from danger, a guard is required, but such guard makes it difficult to pass the thread. If the guard is designed to be opened and closed for the ease of passing of thread, it leads to a cost increase.
Further, in this sewing machine, there is a probability of oil leak from the support parts of the needle bar projecting from the top of the sewing machine arm, and the oscillating shaft projecting to the front side of the sewing machine arm.
In such double chainstitch sewing machine, the needle thread from the thread tension device to the workpiece runs for a long thread pathway extending from the thread tension device to the workpiece by way of the fixed thread guide, first thread take-up, second thread take-up and movable thread guide. Accordingly, it is likely to have effects of stretchable characteristic of thread, and it is hard to obtain an optimum thread take-up amount.
Especially in largely stretchable thread such as woolly thread, the movable thread guide, first thread take-up and second thread take-up act more to stretch thread than to take up thread, so that the take-up action is unstable. It is hard to adjust by the first and second thread take-up amounts and is hence difficult to obtain a double chainstitch of a desired touch. Still more, since the upper cover thread is taken up at the same timing as the needle thread, it is hard to obtain a desired covering chainstitch.
It is hence an object of the present invention to eliminate the difficulty in threading without substantially increasing the cost, by eliminating movable thread take-up members on the upper side and front side of the sewing machine arm, and installing substituent movable thread guide and first and second thread take-ups centrally at the lower end of the needle bar or jaw of the sewing machine arm so as to decrease the dangerous positions for the operator. It is other object of the present invention to avoid the probability of oil leak from the support parts of the needle bar projecting from the top of the sewing machine arm, and the oscillating shaft projecting to the front side of the sewing machine arm.
It is a further object of the present invention to present a double chainstitch sewing machine capable of obtaining a desired stitch tension easily by shortening the thread pathway length from the workpiece to the thread tension device and decreasing effects of thread stretchable characteristic on take-up of needle thread, and a double chainstitch sewing machine related to a flat seam for taking up upper cover thread at optimum timing by installing a thread take-up for upper cover thread independently of a thread take-up for the needle thread.
SUMMARY OF THE INVENTION
In a first aspect of the double chainstitch sewing machine according to the present invention, a movable thread guide for guiding the needle thread is fixed to the lower end of the needle bar. A fixed thread guide is fixed to the jaw of the sewing machine arm. A thread take-up cam is also fixed to the jaw of the sewing machine arm, and the cam section of the thread take-up cam extends in the vertical direction by intersecting with the needle thread pathway between the fixed thread guide and the movable thread guide. The needle thread from the fixed thread guide to the movable thread guide is oscillated up and down from the fixed thread guide by the movable thread guide moving up and down together with the needle bar, and is supplied into the cam section of the thread take-up cam. Thus, by interaction of the movable thread guide and the cam section of the thread take-up cam, the needle thread is taken up from the thread tension device to the needle.
In a second aspect of the double chainstitch sewing machine according to the present invention, a movable thread guide for guiding the needle thread is fixed to the lower end of the needle bar, and a fixed thread guide having mutually opposite right and left thread eyes is fixed to the jaw of the sewing machine arm. A thread take-up cam is also fixed to the lower end of the needle bar, and the cam section of the thread take-up cam is disposed between the thread eyes of the fixed thread guide. The needle thread from the fixed thread guide to the movable thread guide is oscillated up and down from the fixed thread guide by the movable thread guide moving up and down together with the needle bar, and the needle thread between the thread eyes of the fixed thread guide is bent by the vertical motion of the cam section of said thread take-up. Thus, by interaction of the movable thread guide and the thread take-up cam, the needle thread is taken up from the thread tension device to the needle.
According to these aspects of the present invention, since the thread take-up oscillating vertically at the front side of the sewing machine arm and the movable thread guide moving vertically as being affixed to the upper end of the needle bar are eliminated, the operator is liberated from the danger during operation of the sewing machine at the front side and upper side of the sewing machine arm. At the same time, the support parts of the needle bar projecting from the top of the sewing machine arm, and the oscillating shaft projecting to the front side of the sewing machine arm in the conventional sewing machine can be eliminated, and probability of oil leak is avoidable. Further, the movable thread guide of the thread take-up mechanism is attached to the lower end of the needle bar, the fixed thread guide is fixed and installed at the jaw of the sewing machine arm, and the thread take-up cam is attached to the lower end of the needle bar or fixed and installed at the jaw of the sewing machine arm, so that the thread take-up action of the needle thread takes place near the needle, and the thread pathway length from the workpiece to the thread tension device can be shortened, and the thread take-up action of the needle thread is done without substantially having effects of the stretchable characteristic of the thread.
In a third aspect, relating to a double chainstitch sewing machine having a plurality of needles, two or more thread eyes are provided in the movable thread guide, and are disposed obliquely to the motion direction of needle bar.
In a fourth aspect, relating to a double chainstitch sewing machine having a plurality of needles, two or more thread eyes are provided in the movable thread guide, the fixed thread guide is composed

Affiliated with

Also associated with

Rating

Double chainstitch sewing machine does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Double chainstitch sewing machine, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Double chainstitch sewing machine will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2888605