Sewing – Stitch forming – Overseaming
Utility Patent
1998-12-28
2001-01-02
Izaguirre, Ismael (Department: 3741)
Sewing
Stitch forming
Overseaming
C112S188000, C112S260000
Utility Patent
active
06167825
ABSTRACT:
FIELD OF THE INVENTION
The present innovation relates to equipment intended to be fitted to “overlock” machines, such as the well-known machines made by Union Special, Juki, Rimoldi and others, to make them suitable for producing a seam of little thickness, when sewing articles made of sheer knit fabric, such as women's stockings, panty-hose (tights) and the like.
BACKGROUND OF THE INVENTION
The overlock machine is also used as a component of assemblies or lines of machinery—such as, for example those produced by “Takatori” of Japan, “Detexomat” of Great Britain, and “Solis” of Italy which require the manual intervention of an operator only to feed in the pair of pieces of fabric to be assembled and automatically assemble the parts of the knitted fabric that go to make up the panty-hose and/or sew the stocking toes. In these complexes or lines of machinery the overlock machine “automatically” (i.e. also without requiring to be guided and controlled by a person) cuts the pieces of fabric and joins them together by seams with oscillating needles and “loopers”.
The only problem is that the seams that can be produced on these machines, in which the margins of the pieces of fabric being joined are drawn tightly together (the “overlock” seam) have considerable thickness, assuming the form of a cord; this is undesirable both as regards the comfort and “wearability” of the garment, owing to the irritation produced by a seam of this shape, and as regards the aesthetic acceptability of the garment, it being desirable for both of the above reasons, practical and aesthetic, to have a “flat” seam, that is to say a seam that is slightly wider and very much less thick.
To produce such a flat seam (a “flatlock” seam), machines of another and quite different type can be used: these are not, however, “overlock” machines, being unsuitable for cutting the fabrics but only for sewing them, and moreover being unable to operate “automatically”, having instead to be controlled and guided manually by a special operator who must be skilful and expert at the task; such machines cannot therefore be introduced into the abovementioned lines of machinery designed for the automatic assembly of tights.
Union Special overlook machines, as well as JUKI, Rimoldi and other types, have been successfully used to produce this “flatlock” seam only in the production of foundation garments, in which the fabrics used are very much thicker and have a denser weft than those used in the production of women's stockings and tights. This is because in the production of foundation garments, in view of the greater strength of the fabric employed, the fabric pieces can be joined together with seams of loose stitches, made up, that is to say, of slack stitches without tension, in which seam the margins of the pieces of fabric to be sewn together are not drawn tightly together and therefore do not give the seam the cord-like appearance, but nonetheless overlap a certain width.
SUMMARY AND OBJECTS OF THE INVENTION
With the equipment described herein, however, it is possible to make the abovementioned type of overlook machine capable of producing a special form of flat seam for joining together sheer knit fabrics such as those of women's stockings and panty-hose. This particular form of seam is different from that obtained with that type of sewing machine which is not suitable for operating “automatically” and which therefore requires to be controlled and guided by hand by a highly skilled person; but it too is similarly very thin. The result with this equipment is that the margins of the fabric pieces to be assembled have practically no overlap and instead are “edge-to-edge”, i.e. “adjacent” and “juxtaposed”, or overlie or overlap each other only very partially at least when the garment is put on and therefore stretched; and this without in any way detracting from the strength of the seam and of the article.
The present equipment has been designed for sewing machines known as overlooks comprising a throat plate with needle slots and with a stitch finger on the line of the cut, an upper looper, a lower looper, cutting means and means for feeding the two pieces of fabric to be sewn, feeders for feeding needle threads and looper thread, and a looper thread pull-off member, with the object of producing seams with loose stitches, i.e. flatlock seams on sheer knit fabrics for panty-hose or tights. The equipment characteristically comprises in combination:
A—a twin needle fed with two needle threads;
B—an upper looper and a lower looper, one of which is fed with a looper thread with chain stitches, the other being a spreader;
C—a throat plate that has two slots for the needles and a stitch finger (on the line of the cut) of increased width, for forming relatively long seam stitches; and
D—a looper thread pull-off member, modified in order to increase the amount of looper thread pulled off by it each time.
In practice the looper thread, for forming the chain stitches, is fed to the upper looper.
More particularly the aforesaid stitch finger of said throat plate comprises, in the area where the loops are formed, a portion with approximately parallel sides before the final narrowing. Said stitch finger is advantageously also elongate in the longitudinal direction, that is, in the direction in which the fabrics to be sewn are fed. In addition, said stitch finger of the throat plate is reduced, i.e. made thinner, on the underside, to make way for the movements of the lower looper.
The lower spreader is reduced, i.e. made thinner, so as not to interfere with the throat plate and with the stitch finger of the latter. Similarly the upper looper is advantageously reduced, i.e. made thinner, so as to help the threads to run better and to avoid interferences.
The looper thread pull-off member, which is a thread-pulling arm oscillating with the moving assembly of the bar of the needles, is positioned on the needle bar at an advanced angle in order to increase the active stroke of said pull-off member and thereby increase the amount of looper thread pulled off at each downward stroke of the needles.
With the above equipment the result is basically a seam consisting of three threads forming three series of stitches, specifically:
a) a first series of short stitches, formed with a first needle thread, which extend across the “line of the cut”, passing out of one of the two pieces of fabric being joined together and entering the other at positions relatively near to the cut edges;
b) a second series of longer stitches, formed with a second needle thread, which stitches also extend across the line of the cut, passing out of one of the two pieces of fabric being assembled and entering the other at a greater distance from the same line of the cut than the stitches forming the aforesaid first series of stitches, so that the shorter stitches of the first series of stitches lie inside the longer stitches of the second series of stitches; and
c) a third series of stitches, formed with “slack” stitches of a looper thread, much longer and “slacker” than those of the first two series of stitches, which stitches of the third series form the “chain” seam, extending across the line of the cut and forming chain stitches with the first and second needle threads.
It follows from the structural characteristics of the seam described above that, under the stretching of the garment as it is put on, the seam becomes wider and quite flat, with virtually no overlapping of the fabric pieces. This has the obvious advantages of greater comfort and a much more pleasing appearance of the garment. There is no disadvantageous impact on either the practical or aesthetic effect from the fact that the width of the flat seam produced in this way cannot be made to equal that obtained with the type of seam produced with only manual sewing machines; because in fact, from the aesthetic point of view, it is actually decidedly preferable, in tights and stockings, for the width of the seam to be limited.
The various features of novelty which characterize the invention are pointe
Golden Lady S.P.A.
Izaguirre Ismael
McGlew & Tuttle P.C.
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