000001
`
`BEDGEAR 1015
`IPR of U.S. Pat. No. 8,566,982
`
`

`
`U.S. Patent
`
`Jan. 2, 2001
`
`Sheet 1 of 7
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`US 6,167,825 B1
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`

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`U.S. Patent
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`Jan. 2, 2001
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`Sheet 2 of 7
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`US 6,167,825 B1
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`U.S. Patent
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`Jan. 2, 2001
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`Sheet 3 of 7
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`U.S. Patent
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`Jan. 2, 2001
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`Sheet 4 of 7
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`US 6,167,825 B1
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`U.S. Patent
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`Jan. 2, 2001
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`Sheet 5 of 7
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`US 6,167,825 B1
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`U.S. Patent
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`Jan. 2, 2001
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`Sheet 6 of 7
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`US 6,167,825 B1
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`U.S. Patent
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`Jan. 2, 2001
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`Sheet 7 of 7
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`US 6,167,825 B1
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`US 6,167,825 B1
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`1
`EQUIPMENT FOR SEWING MACHINES FOR
`OBTAINING A FLAT SEAM WHEN JOINING
`PIECES OF SHEER KNIT FABRIC
`
`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 “over-
`lock” 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 pro-
`duced 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
`
`is
`it
`With the equipment described herein, however,
`possible to make the abovementioned type of overlook
`machine capable of producing a special form of fiat seam for
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`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 com-
`prises 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.
`
`for forming the chain
`
`In practice the looper thread,
`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
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`US 6,167,825 B1
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`3
`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 fiat, 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 disadvan-
`tageous impact on either the practical or aesthetic effect from
`the fact that the width of the fiat 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 pointed out with particularity in the claims
`annexed to and forming a part of this disclosure. For a better
`understanding of the invention, its operating advantages and
`specific objects attained by its uses, reference is made to the
`accompanying drawings and descriptive matter in which
`preferred embodiments of the invention are illustrated.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`In the drawings:
`FIG. 1 shows a highly diagrammatic perspective view of
`a pair of panty-hose or tights;
`FIGS. 2, 3 and 4 show an enlarged detail of the area
`indicated by arrow fII, a cross section on III—III from FIG.
`2 and an enlarged view of a detail indicated by arrow fIV in
`FIG. 1;
`FIG. 5 shows a perspective diagram of the feeding of the
`threads in an overlock machine of the type indicated above;
`FIGS. 6 and 7 are a diagrammatic lateral view of a detail
`from FIG. 5 to illustrate the two extreme positions of the
`needles and the increased feeding of the thread to the upper
`looper;
`FIG. 8 shows a view on the plane VIII—VIII as marked
`in FIG. 7 which illustrates the throat plate modified to
`produce the seam shown in FIGS. 2 to 4;
`FIGS. 9, 10 and 11 show a view on IX—IX, an enlarged
`section of X—X as marked in FIG. 8 and a perspective view
`of the underside of said throat plate;
`FIGS. 12, 13, 14 and 15 show diagrammatic views
`roughly on the plane marked XII—XII in FIG. 7 with
`various positions assumed by the members illustrated here
`during one cycle; and
`FIGS. 16, 17 and 18 show perspective views of the
`modified looper and spreader and a view on the plane
`marked XVIII—XVIII in FIG. 16.
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENT
`
`The accompanying drawing, with initial reference to
`FIGS. 1 to 4, shows the so-called “flatlock” seams of loose,
`flat stitches, which are used to close the toes P and to connect
`the two components, each of which consists of a leg G and
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`a portion of the body section C, along the crotch, with the
`possible addition of a gusset T. The toe seam is marked CP,
`while the seam along the crotch line is given the general
`reference CC and is shown in greater detail in FIGS. 2 to 4.
`In the seam area the fabric of the two pieces L1 and L2,
`which are sewn together, can optionally be formed by two
`portions of non-run fabric marked I, while further away, the
`fabric of the article can be made with a normal knit and is
`therefore more elastic and more suited to the function of the
`
`article, using techniques known per se; the non-run portions
`I along the pieces L1 and L2 that are to be sewn give the
`knitted stitches greater resistance to unravelling because of
`the cut made by the overlock machine along the lines T.
`The seam is made with two needle threads F1 and F2 and
`
`one looper thread F3. Thread F1 makes long stitches, while
`thread F2 makes short stitches positioned in an intermediate
`position relative to that occupied by the long stitches formed
`by thread F1; the third thread F3 is fed to a looper and forms
`the chain stitches, which are particularly visible on the
`opposite side to that on which the long stitches of thread F1
`and short stitches of thread F2 can be seen. The long stitches
`and short stitches of threads F1 and F2 respectively are
`particularly visible in FIG. 2, while the looper stitches, the
`so-called chain stitches, formed by thread F3 are visible
`more in FIG. 4. Thread F1 for forming the long stitches is
`fed to the needle that passes through the pieces L1 and L2
`at the furthest position from the line of the cut T, while
`thread F2 is fed to the needle closest to the line of the cut T.
`
`The so-called flatlock seam described above is particu-
`larly effective because under the conditions of tension of the
`fabric when the article is worn,
`the two pieces L1 and
`L2—which are connected by the seams such as CP and such
`as CC formed by threads F1, F2 and F3—are basically
`brought edge-to-edge along the lines of the cut T with no
`overlap and especially without that cord-like bunching up of
`the fabrics which is present in the conventional structure of
`seams produced by overlock machines. The seam can be
`produced in such a way that the stitches formed by threads
`F1 and F2 lie primarily on the outside while the stitches
`formed by thread F3 of the chain-stitch seam produced with
`the thread fed to the looper are on the inside of the article
`when worn. However, the possibility of choosing the reverse
`position of that indicated is not excluded.
`Essential considerations in the seam that is to be produced
`are what strength is desired and how much stretch capacity
`is required of the two pieces L1, L2 sewn together, which
`stretch is produced by increasing the length of the long
`stitches and short stitches (with threads F1 and F2) and
`likewise the chain-stitch seam (with thread F3).
`FIGS. 5 ff show the equipment with which a sewing
`machine of the overlock type as indicated above is fitted to
`produce the seam defined above. Of the complicated over-
`lock machine of the conventional type, well-known to the
`experts, only certain significant parts are shown, notably
`those that form part of said modified equipment for adapting
`the machine to produce the seam defined above. Typical
`parts of the overlock machine are referred to in the course of
`the following description, with its modifications and variants
`explained.
`The three threads F1, F2 and F3 are fed, as shown in FIG.
`5, through respective tension discs 11, 12 and 13 and suitable
`thread guides. Thread F1 is fed to needle 15 which is furthest
`from the cut edge, i.e. the line of the cut T shown in the
`drawing as a chain line, particularly in FIGS. 5, 8, 10, 11 and
`12. 17 indicates the needle closest to the line of the cut and
`fed with thread F2. Both the needles 15 and 17 are fixed at
`
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`US 6,167,825 B1
`
`5
`19 to the needle bar 21, which oscillates about a shaft 23.
`Said shaft controls a moving assembly that must be made to
`oscillate and that comprises the needle bar 20, the needles 15
`and 17 and a thread-pulling arm 25 whose function is to pull
`off thread F3 for the chain stitch formed with the help of an
`upper looper 30 described below. This thread-pulling arm 25
`replaces the conventional thread-pulling arm which is out-
`lined at 25X, and, like the latter, is positioned between two
`adjacent arms 27, each of which has a guide hole 27A at its
`end for the thread F3 to be fed to the upper looper. The shape
`of the thread-pulling arm is modified and the position of this
`thread-pulling arm 25 is further forward—compared with
`the position of the conventional thread-pulling arm 25X—in
`the direction of arrow F21, which indicates the movement of
`the moving assembly of the needle arm 21 and of the
`thread-pulling arm 25 in the direction in which the needles
`15 and 17 move down when passing through the pieces L1,
`L2 of fabric to be sewn. The result is that (see in particular
`FIG. 7) the amount of thread F3 pulled off by the thread-
`pulling arm 25 for forming the chain-stitch seam is longer
`than the amount of thread that could have been pulled off by
`a thread-pulling arm 25X of the conventional type, which
`stops before the arm 25 (as shown in FIG. 7) with respect to
`the holes 27A of the arms 27.
`
`The numeral 30 denotes an upper looper to which thread
`F3 is fed; thread F3 is guided by thread guide means 32 after
`having been guided by the holes 27A. The numeral 34
`denotes a lower spreader having a forked end for collecting
`threads F1 and F2 when these have been brought by needles
`15 and 17 down below fabric pieces L1 and L2 by the
`oscillation of the moving assembly 21, 17, 15, 25 in the
`direction of arrow 121 shown in FIGS. 6 and 7.
`
`The numeral 36 is a general indication for a throat plate
`or needle plate whose general shape is analogous to that of
`known plates of this kind for the formation of seams in the
`abovementioned conventional machines, but its shape has
`been modified as indicated here: the throat plate 36 com-
`prises two longitudinal slots 38 and 40 for the two needles
`15 and 17, respectively, and comprises, next to slot 40, a
`stitch finger 42 situated generally on the position of the line
`of the cut T. It is on this line that knives act in a space 43
`provided for this purpose in the throat plate 36. The stitch
`finger 42 comprises an initial portion with straight sides
`42A, 42B and with an approximately constant width D that
`is greater than the corresponding dimension of the stitch
`finger present in the conventional type of throat plate; this
`constant dimension D extends through the area where the
`needles 15 and 17 and the upper looper 30 and lower looper
`34 operate. In dimension E,
`the stitch finger 42 is also
`increased in the longitudinal direction,
`that
`is,
`the feed
`direction fA indicated in FIG. 8, which is the direction in
`which the pair of fabric pieces L1 and L2 are fed, cut along
`the line of the cut T and sewn; the stitch finger 42 then tapers
`to an almost sharp end 42C. Characteristically, the stitch
`finger 42 is also reduced on the underside to allow room for
`the lower spreader 34, the movement of which is similar to
`that of the conventional spreaders; 42S denotes the reduced
`or thinner underside of said stitch finger 42. As an order of
`magnitude, the constant dimension D may be around 3 to 5
`mm and more particularly around 4 mm for sheer panty-hose
`articles. The width of each of the longitudinal slots 40 and
`38 is also of the order of a millimeter. These dimensions are
`
`used to determine the distance between the edge 42A of the
`stitch finger 42 and the position of the needles 15 and 17
`when lowered by the oscillating moving assembly of the arm
`21 through the two fabric pieces L1 and L2 and the slots 40
`and 38, for the formation of the various stitches as indicated
`and clearly visible in FIGS. 2, 3 and 4.
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`FIGS. 12 to 15 show how the seam is produced with
`needles 15 and 17 and loopers 34 and 30. As the needles
`descend through the pieces L1 and L2 and through the slots
`38 and 40, and as said needles first begin to move back up
`again, the threads F1 and F2 bulge out slightly (FIG. 12)
`causing them to be caught by the forked end of the lower
`spreader 34; this spreader 34 pushes threads F1 and F2, as
`shown, from the position of FIG. 12 through intermediate
`positions and on to the position of FIG. 13, in which threads
`F1 and F2 are positioned to form two eyes through which the
`upper looper 30 then passes; the upper looper 30 pulls thread
`F3 through these two eyes and disengages them from the
`spreader 34 as shown in FIG. 14;
`the upper looper 30
`advances with thread F3 until it has positioned it around the
`raised needles 15 and 17; the needles then descend again as
`can be seen by comparing FIGS. 13 and 14, and pass
`between looper 30 and the loop formed by thread F3 so that
`threads F1 and F2 engage with thread F3 which is intended
`to form the chain stitches. FIG. 15 shows the retracted
`
`position of looper 30 which draws back from the eyes
`formed by threads F1 and F2 taking with it thread F3 which
`is now caught around the needles 15 and 17. This process is
`basically similar to that performed by corresponding com-
`ponents in conventional machines; however, the design of
`the stitch finger 42 with respect to slots 38 and 40, and the
`consequent amount of threads F1 and F2 pulled off during
`the stitch-forming operations, as well as the increased
`amount of thread F3 pulled off by the thread-pulling arm 25,
`have the effect that the stitches of the seams shown in FIGS.
`
`2 to 4 are sufficiently long and therefore the seam is fiat, i.e.
`the stitches are loose or slack. Hence in the flattened and
`
`coplanar position of the two fabric pieces L1 and L2 sewn
`together, and in particular with the two fabrics stretched
`apart (as occurs when putting the garment on), the thickness
`of the seam is very little greater than the thickness of the
`fabrics, and there is not that cord-like formation typical of
`seams produced with the conventional equipment of the
`overlock machines described above.
`
`For greater efficiency of the parts of the equipment
`described, the upper and lower loopers 30 and 34 respec-
`tively can be slightly modified compared to the correspond-
`ing loopers of the normal equipment of these conventional
`overlock machines, as shown in particular in FIGS. 16 to 18.
`In these figures, 30X and 34X indicate the parts that are
`made smaller, i.e. reduced by removal of material by com-
`parison with the conventional form of these loopers 30 and
`34 as shown in chain lines. These measures, in combination
`with the reduction or shrinking at 42S of the underside of the
`stitch finger 42 ensure the smooth movement of the two
`loopers without interfering with the throat plate 36, even
`when said stitch finger 42 is made larger—as described
`earlier—than the conventional shape of stitch finger as used
`in conventional throat plates equivalent to 36. The reduction
`42S also helps the feeding of the thread F3 forming the chain
`stitches.
`
`The particular shape and particular length of the stitch
`finger 42 mean that the stitches formed with the threads F1,
`F2 and F3 around the area of the sides 42A and 42B of said
`
`stitch finger 42 are longer and are retained for a longer
`period of time, with the result that they are looser (have less
`tension). With the same aim of reducing the tension and
`increasing the slackness of the stitch formed by thread F3,
`the thread-pulling arm 25, which is the tension device of
`thread F3 fed to the upper looper 30, is modified in terms of
`its position on the needle bar 21 as described earlier.
`While keeping to the above-indicated essential features of
`the innovation, it is possible within certain limits to vary the
`
`00001 1
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`
`US 6,167,825 B1
`
`7
`width of the stitch finger 42 in order to obtain, within the
`sense of a flat seam, a slightly wider or slightly narrower
`seam, depending on what is felt desirable in any particular
`case, e.g. depending on the purpose of the seam (on the toes
`or on the crotch). In correlation with this it is also possible,
`within certain limits, to vary the distance between the two
`needles 15 and 17 and, correspondingly, the dimensions of
`the slots 38, 40.
`Thus, as an example, for forming the body section of
`tights a throat plate 36 can be used that has an even wider
`stitch finger 42 in order that the stitches made with thread F1
`and thread F2 are even longer, in order to produce a seam of
`greater width. For the closing of the toes of stockings and of
`the legs of panty-hose, by contrast, a throat plate 36 having
`a somewhat narrower stitch finger 42 can be used, the effect
`being to make the two series of stitches formed by threads
`F1 and F2 somewhat shorter, so that only a limited width of
`fabric is picked up by the stitches of the seam and so that,
`as a consequence, the resulting seam is somewhat narrower.
`Those skilled in the art wishing to carry out the present
`innovation will have no difficulty in deciding
`experimentally, case by case, the ideal width for the stitch
`finger 42 to produce a seam of the desired width, and to
`decide, as a consequence of this, what the distance should be
`between needles 15 and 17, varying the thickness to be
`interposed between them on the attachment 19 accordingly.
`It is also possible within certain limits to vary the number of
`seam stitches per unit length to suit the strength of the knit
`fabrics.
`What is claimed is:
`
`1. Equipment for conventional overlooks comprising a
`throat plate with needle slots and with a stitch finger on a line
`of a cut feeders for feeding needle threads and a looper
`thread;
`a twin needle fed with the needle threads;
`an upper looper and a lower looper, one of which is fed
`with a looper thread, the other being a spreader;
`a throat plate having two slots for the needles said stitch
`finger being positioned adjacent one of said two slots
`said stitch finger having a width for forming seam
`stitches and comprises, in an area where stitch loops are
`formed, a portion with approximately parallel sides
`before a final narrowing and is reduced,
`i.e. made
`
`8
`thinner on underside to make way for movements of the
`lower looper; and said looper thread pull-off member is
`arranged to increase an amount of looper thread pulled
`off by it each time;
`looper thread pull-off member which is a thread-pulling
`arm oscillating with said twin needle, said looper
`thread pull-off member is positioned on a needle bar of
`said twin needle at an angle which is further forward in
`a direction in which the twin needle moves down, in
`such a way as to increase an active stroke of said
`pull-off member and thereby increase an amount of the
`looper thread pulled off at each stroke.
`2. Equipment according to claim 1, wherein: said stitch
`finger is longitudinally elongate.
`3. Equipment according to claim 1, wherein: said spreader
`is reduced, i.e. made thinner at a portion so as not to interfere
`with the throat plate and with the stitch finger, the upper
`looper is reduced, i.e. made thinner at a portion to avoid
`interferences with one of said lower looper, said throat plate
`and said twin needle.
`
`4. An apparatus for forming an overlock seam between
`two fabric portions, the apparatus comprising:
`a throat plate positionable adjacent the two fabric portions
`in an overlapped condition, said throat plate defining
`two needle slots;
`a twin needle fed with two needle threads and movable
`
`through said two needle slots and the overlapped fabric
`portions;
`a stitch finger arranged adjacent one of said needle slots
`and positionable on a cut line of the seam;
`a first looper arranged as a spreader of the needle threads;
`a second looper being fed with a looper thread and for
`connecting the looper thread with the needle threads;
`a looper thread pull-off member for feeding the looper
`thread to said second looper, said looper thread pull-off
`member is arranged to cooperate with a size of said
`stitch plate and said loopers to form a plurality of
`stitches having length to have the overlook seam lie
`substantially flat when the two fabric portions are
`coplanar.
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`000012
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