EP1620592B1 - Sewing machine - Google Patents

Abstract

A sewing machine having two needles ( 8, 9 ) that are at an angle (alpha) to the vertical axis of a piercer (C) is provided. After the piercer has pierced the item to be sewn with a tip thereof, the needles pierce through vertical slits ( 27 ) in the piercer (C). The two needles are driven in a direction of the respective axis thereof, i.e., in a direction of the axes (V<SUB>1</SUB>, V<SUB>2</SUB>).

Description

The invention relates to a sewing machine according to the preamble of claim 1 and a engraver for a sewing machine.

Hemstitch sewing machines and two-needle sewing machines have been known for around a hundred years and still work on the same principle today. This is that by two needles, each associated with a gripper, two parallel juxtaposed zig-zag seam sections are generated. In order to separate the two seams from each other, the weaving threads are slightly pushed apart and a recess or a hole is formed in the sewing material with a leader. To be able to wrap around the spaced-apart woven threads at the edges of the holes with the needles, deep axial grooves are recessed in the engraver laterally. Due to the tension of the weaving threads, when the stitcher is pierced in the sewing material, a free passage for the needles remains in the grooves. In order to be able to guide the needles through these two opposing passages, the latter are pivotably mounted at the lower end of the common needle needle oscillating perpendicular to the needle plate. and pre-piercing bar attached and swinging. That is, a first pass is made with inwardly pivoted needles, so that their tips in the lateral grooves of the engraver led by the created in the free space of the grooves opening in the fabric down to the grippers. During piercing, the needles are so strongly applied to the grooves that they have a bend. The subsequent stitch is then carried out with swung back, that is substantially vertically penetrating into the fabric then not bent needles. In the subsequent stitch, the needles are pivoted back inwards and are bent when penetrating into the fabric and abut the grooves of the engraver. They are also bent by the grippers something aside, so that the hook tip can detect the upper thread loop.

This process, which has been used unchanged for a century, has the disadvantage that lateral forces act on the needle at every other stitch and bend it. Furthermore, it is not ensured that the internal stitch, ie the stitch, in which the needles are bent in the grooves of the engraver, press all web threads to the outside. Often there are still individual Webfäden within the recess, which worsen the optical image of the hemstitch, because they traverse the hole formed. Another disadvantage is that the tips of the needles with complete engagement in the fabric are very close to each other and consequently the gripper tips of the two grippers under the throat plate must be very close to each other. Due to the close proximity of the two grippers the engraver can not penetrate very deeply into the fabric or its tip must have a large Konizitätswinkel to form sufficiently large holes. This has the consequence that when spreading the Web threads by the rapid penetration of "blunt" tip of the engraver can tear the Web threads. Such a hemstitch sewing machine is in the US-A 2,093,588 disclosed.

In the further known from the International search report DE-109 522 a device for producing hollow effects on embroidery machines is known in which a hole in the embroidery material is initially produced with a drill and, after the drill has been withdrawn from the embroidery material at high speed, a needle at an acute angle to the drill axis for stitch formation in the prefabricated Hole is introduced. Such a device can only work reliably if the embroidery material has a suitable structure and the hole produced by the drill does not close when the drill is withdrawn. In addition, with this known device during the stitching of the hole, the hole cross section can not be maintained constant.

The further mentioned German patent specification DE-100 814 relates to a stub device, with which the impressions of the hollow embroidery is prevented. When stubbing is not the edge of the hole, created by a drill hole by a sewing needle, which interacts with a gripper, bordered. Only the hole that has already been enclosed will be widened again. It is a completely different device.

Object of the present invention is to provide a sewing machine and a engraver, which overcomes the disadvantages of the known and allows the proper production of hollow seams both loosely as well as tightly woven fabric.

This object is achieved by a sewing machine having the features of patent claim 1 and a engraver for a sewing machine according to claim 10.
Advantageous embodiments of the sewing machine are defined in the dependent claims.

It succeeds with the inventive sewing machine hollow seams with larger holes and greater distance of To create holes. Furthermore, there is no bending of the needles, since they are neither pressed to the side during piercing nor carry out a translatory movement, but always oscillate exactly in the needle axis. Due to the oscillating in an acute angle to the engraver needles needle tips are the full penetration of the fabric by a multiple further apart than before and it can be the two grippers in greater mutual distance and also exactly at the sewing technically optimal location. It can be used with horizontal horizontal axis of rotation gripper, so that the changing of the lower thread bobbins without lifting the material from the stitch plate is possible. The farther apart grippers allow the use of a piercer and a piercer with much less conicity, ie with much longer tip, so that the weaving threads are pushed apart less quickly during piercing and thereby yarn breaks can be prevented. Since the two needles lying in a V-shape penetrate the piercer within the opening formed in the sewing material by the piercer, it is avoided that individual weaving threads are not looped around by the sewing threads. The always oscillating in the direction of the needle axis needles are not subject to bending forces and therefore a needle breakage can be excluded by material fatigue. In the further are the ears of the Needles perfectly accessible for the insertion of the needle thread.

The engraver according to the invention can be fastened to a household sewing machine and makes it possible to produce hollow seams even in the private sector.

Figur 1

eine Aufsicht auf ein Nähgut und Horizontalschnitt durch die beiden Nadeln, geführt in den Nuten des Stechers (Nähgut angedeutet),

Figur 2

einen Horizontalschnitt über dem Nähgut in Figur 1, Nadel nach aussen geschwungen,

Figur 3

ein Horizontalschnitt über dem Nähgut beim dritten Stich (Nadeln in Nuten des Stechers verlaufend Figur 1', wie Figur 1 Beginn des folgenden Hohlsaumloches),

Figur 4

einen Vertikalschnitt durch eine Hohlsaum-Nähmaschine nach dem Stand der Technik im Bereich der Nadeln und Greifer mit eingeschwenkten Nadeln,

Figur 5

einen Vertikalschnitt durch eine Hohlsaum-Nähmaschine nach dem Stand der Technik im Bereich der Nadeln und Greifer mit ausgeschwenkten Nadeln,

Figur 6

eine Seitenansicht von Vorstecher und einem Stecher mit zwei vertikalen Schlitzen,

Figur 7

eine Seitenansicht der beiden Stecher in einer weiteren Ausgestaltung der Erfindung,

Figur 8

eine Aufsicht auf die Stichplatte mit den Transporteurriemchen,

Figur 9

einen Vertikalschnitt durch die erfindungsgemässe Hohlsaum-Nähmaschine im Bereich der Nadeln und Greifer (Einstichstelle aussen) und

Figur 10

einen Vertikalschnitt durch die erfindungsgemässe Hohlsaum-Nähmaschine im Bereich der Nadeln und Greifer (Einstichstelle innen),

Figur 11

eine vergrösserte Darstellung der Nadeln und der Ausnehmung im Stecher gemäss Figur 9 und Stichstelle,

Figur 12

eine vergrösserte Darstellung der Nadeln und der Ausnehmung im Stecher gemäss Figur 10 und Stichstelle im Stichbild,

Figur 13

einen Vertikalschnitt durch die vertikal liegende Nadel einer Haushalt-Nähmaschine und einem zur Nadel in spitzem Winkel liegenden Stecher bei eingestochener Nadel,

Figur 14

einen Vertikalschnitt durch die vertikal liegende Nadel einer Haushalt-Nähmaschine und einem zur Nadel in spitzem Winkel liegenden Stecher bei angehobener Nadel,

Figur 15

eine Ansicht eines Stechers mit seitlich liegenden Nuten,

Figur 16

eine Seitenansicht des Stechers gemäss Figur 15 mit abgesenkter Nadel (in der Nut liegend),

Figur 17

eine schematische Seitenansicht einer erfindungsgemässen Hohlsaum-Nähmaschine,

Figur 18

eine schematische Seitenansicht einer Haushalt-Nähmaschine mit einem erfindungsgemässen Stecher.

Reference to an illustrated embodiment, the invention is explained in detail. Show it

FIG. 1

a view of a fabric and horizontal section through the two needles, guided in the grooves of the engraver (sewing material indicated),

FIG. 2

a horizontal section above the fabric in FIG. 1 , Needle swung outwards,

FIG. 3

a horizontal section above the fabric at the third stitch (needles in grooves of the engraver running FIG. 1 ' , as FIG. 1 Beginning of the following hemstitch hole),

FIG. 4

a vertical section through a hemstitch sewing machine according to the prior art in the field of needles and grippers with pivoted needles,

FIG. 5

a vertical section through a hemstitch sewing machine according to the prior art in the field of needles and grippers with pivoted needles,

FIG. 6

a side view of Vorstecher and a engraver with two vertical slots,

FIG. 7

a side view of the two engravers in a further embodiment of the invention,

FIG. 8

a view of the throat plate with the transport straps,

FIG. 9

a vertical section through the inventive hemstitch sewing machine in the field of needles and grippers (puncture site outside) and

FIG. 10

a vertical section through the inventive hemstitch sewing machine in the field of needles and grippers (puncture site inside),

FIG. 11

an enlarged view of the needles and the recess in the engraver according to FIG. 9 and sting site,

FIG. 12

an enlarged view of the needles and the recess in the engraver according to FIG. 10 and stitching point in the stitch image,

FIG. 13

a vertical section through the vertical needle of a household sewing machine and a needle lying at an acute angle engraver with pierced needle,

FIG. 14

a vertical section through the vertical needle of a household sewing machine and a needle lying at an acute angle Engraver with raised needle,

FIG. 15

a view of a engraver with lateral grooves,

FIG. 16

a side view of the engraver according FIG. 15 with lowered needle (lying in the groove),

FIG. 17

a schematic side view of an inventive hemstitch sewing machine,

FIG. 18

a schematic side view of a household sewing machine with an inventive engraver.

For a better understanding of the invention and the differences from the prior art are in the FIGS. 1 to 5 the formation of a hemstitch with a conventional hemstitch sewing machine according US-A 2,093,558 illustrated and explained.

In FIG. 1 is the fabric 1 can be seen in the already two hemstitch openings or holes A have been generated. The Vorstecher, whose cross-section may be, for example, oval, has penetrated into the fabric 1. The engraver C located behind at a distance has also penetrated the sewing material 1. In the engraver C are laterally two axially extending grooves 3 can be seen (see in particular FIG. 2 ), in which in FIG. 1 already the two needles 8 and 9 are. Due to the spreading movement of the weaving threads through the penetration of a piercer twice, first of the piercer D and then of the piercer C, the weaving threads are pushed to the side and the needles 8 and 9 can penetrate into the recess A. In the second sewing step according to FIG. 2 are the needles 8 and 9 pivoted outwards, swinging outwards in the sewing language, and pierce outside the recess A directly into the fabric 1 a. At each puncture of the two needles 8 and 9, the two upper threads 6 and 7 devoured with the lower threads, not shown, and when pulling out the needles 8.9 from the fabric 1, the stitches are contracted according to the set thread tension and form along the recess A forming zig -Zack seams. FIG. 3 shows the third puncture, in which the two needles 8 and 9 are again guided in the grooves formed by the grooves 3 of the engraver C. FIG. 1 ' represents the beginning of the production of a new recess A after the fabric 1 has been transported with the conveyor by one step in the direction of the arrow 5.

The swinging of the two needles 8 and 9 is in the FIGS. 4 and 5 shown closer. The two needles 8 and 9 are pivotally connected to two-armed levers 10 and 11 about pivot axes 12,13. The two needles 8 and 9 are attached to the first lever arms 14 and 15; the second lever arms 16 and 17 are connected to drive rods 18 and 19. The two two-armed levers 10 and 11 are articulated at the front end of a vertically up and down movable Stecherstange 20. Besides the two Needles 8,9 are on the Stecherstange 20 and the two engravers C, D, namely the Vorstecher D and the engraver C, attached. The engraver C, D and the two needles 8,9 are consequently moved up and down together with the piercing rod 20 perpendicular to the throat plate 21. The oblique needles 8,9 experience a bending towards the engraver ..

Below the throat plate 21, the feed dog 23 and the two grippers 24,25 are visible.

In FIG. 4 is the Stecherstange 20 with the needles 8 and 9 and the punches D and C in the highest position in which the fabric 1 can be pushed under the needles 8 and 9 and Stecher D and C, respectively. The two needles 8 and 9 are steady, ie their tips are close to each other and they are also (in FIG. 4 not visible) according to FIG. 1 in the lateral grooves 3 of the second engraver C. In this mutual position, ie inclined needles 8 and 9, these are guided together with the punches D and C of the needle bar 20 through the fabric 1 and the needle plate 21 down. The two needles 8 and 9 perform a translational motion, ie their tips penetrate close to each other lying in the fabric and the further down driving (not shown) displace the two needles because of their oblique position the fabric 1 to the outside. Shortly before the Hubumkehr the Stecherstange 20, the two upper thread loops of the Gripper tips of the two grippers 24 and 25 detected and engulfed with the lower thread.

When puncture according to FIG. 2 the two needles 8 and 9 swing outwards (see also FIG. 5 ) and are now perpendicular to the throat plate 21. They sting through the fabric 1 through and form the first zig-zag stitch. Out FIG. 5 It can be seen that the two hook tips must be spaced so far that the two needles 8 and 9 can slide past it. This means that the thread loop transfer in any case, neither in zusammengeschwungenen needles as well as in spaced apart needles 8,9 sewing technology optimal.

In the schematic representations according to FIGS. 9 and 10 which shows the geometric arrangement of the two needles 8 and 9 in the embodiment of the sewing machine N1 according to the invention FIG. 17 shows, it can be seen that the needle axes V ₁ and V _{2 are} at a preferably acute angle alpha to the axis of movement Y of the piercing rod 20. The engraver rod axis Y is perpendicular to the surface of the throat plate 21. The movement drive for the two needles 8.9 takes place in the two needle axes V ₁ and V ₂ with an independent from the drive of the engraver rod 20 but synchronous drive 22nd

When piercing the needles 8,9 no translational movement takes place. The position of the puncture through the fabric 1 and the Nähgutebene in the holes is not changed and there are no lateral forces on the needles 8,9 and the weaving threads of the fabric 1 during piercing. To these intersecting feed paths of the needles 8.9 to allow the two needle axes V ₁ and V ₂ are offset in the sewing direction 5 by at least one needle diameter, ie the needles 8,9 intersect (see. FIG. 11 ). The point of intersection K _{1 of} the two needles 8, 9 lies within the engraver C. For this purpose, in the engraver C (cf. FIG. 6 ) two parallel to the longitudinal axis (Y) extending slots 27 are inserted. Each of these slots 27 is traversed by one of the two needles 8.9, after the engraver C has penetrated into the fabric 1 and the recess A formed and the weaving threads of the fabric 1 has gently pushed apart. Alternatively, a single recess may be provided for both needles 8,9. In a further embodiment of the engraver C can be formed on this oblique grooves 28 which form the passage for the needles 8.9 within the Stecherquerschnitts (see. Figures 15/16 ). The two V-shaped oscillating needles 8,9 are at an angle of preferably 60 ° to each other. This entangled position causes with fully inserted needles 8.9 whose tips with that in the corresponding eye 30th Guided upper threads 6,7 are not as close to each other as in the prior art, but in much greater distance. This makes it possible to rotate the two grippers 24,25 vertically, ie their axes of rotation 28,29 are horizontal. This gripper arrangement makes it possible further to form the engraver C much longer and thereby significantly reduce the taper of its tip 30 and thus make the spreading of the weaving threads during piercing gentler because slower and thus to prevent yarn breakage. Furthermore, the vertically encircling grippers 24, 25 allow the bobbins accommodated therein to be exchanged without lifting the material 1 from the throat plate 21. Further, such vertical grippers 24,25 seen in sewing direction 5 can be arranged behind the needles 8,9 and thus sewing technique a better stitch pattern can be obtained. The two preferably designed as a rotary gripper gripper 24,25 may be driven synchronously or in opposite directions.

In FIG. 11 is the point of intersection K _{1 of} the two needles 8,9 on the sewing material 1 on the throat plate 21. In this position, the tips of the needle meet 8.9 in a lateral distance x to the engraver C on the fabric 1 and penetrate this at an angle alpha. So they form the outer punctures of the formed around the hole A zig-zag seam. By a pivoting or a parallel shift the needle axes V ₁ , V ₂ , as in FIGS. 10 and 12 ₂ , the point of intersection K _{2 of} the needles 8, 9 shifts downward, specifically into the plane of the throat plate 21 or of the sewing material 1, which lies on the throat plate 21 (in FIGS FIGS. 9 and 10 Sewing material 1 not shown). The two needle tips there consequently penetrate the material level within the engraver C, ie in the recess (webfädenlosen) formed by the engraver C. If the engraver C has two laterally attached, obliquely to the piercing axis lying peripherally open grooves 30, the stitch formation happens analogously.
Alternatively to the in FIG. 6 shown engraver C with two vertical slots 27, as in the FIGS. 9 and 10 is used, two engravers C could each be provided with a slot and the two needles 8.9, of course, correspondingly larger spaced, are guided by the engraver C. In this method, the recesses A would not synchronously provided on both sides with zig-zag seams, but each offset by a recess A (see. FIG. 7 ). This also means that a hemstitch seam can be produced with only one needle if only one side of the recesses A formed is to be provided with stitches.

The shift of the point of intersection K of the needles 8,9 down, as already mentioned, by changing the two angles alpha to the vertical axis Y or by a Parallel displacement of the needle axes V ₁ and V ₂ carried out to the outside. The drive direction of the needles 8.9 in the axial direction V ₁ or V ₂ is always maintained. That is, there is no translational movement of the needles 8,9 as in the previous method according to FIG. 4 , As a result, a displacement of weaving threads during the advance of the needles 8,9 and laterally acting on the needle 8 forces can be prevented.

In a preferred embodiment of the invention, instead of a conventional conveyor 23, which performs a translatory movement in the throat plate 21, a twin conveyor 31 according to FIG. 8 , This comprises two easily over the surface 32 of the needle plate 21 projecting or guided over this conveyor belts 33. Between the two conveyor belts 33 which are gradually driven and have a freewheel, are preferably two clamping and transport rollers 34,35. These are synchronously drivable and provided with a freewheel. is located above the one transport roller 34, attached to the presser foot, which has been omitted for the sake of clarity in the drawings, a second roller with which the fabric 1 can be kept clamped. By this inventive conveyor 31, the fabric is held not only the side of the needle hole 36, but also in front of and behind this as in an embroidery hoop. The fabric can therefore neither during stitch formation, glide uncontrolled during the feed. The drive of the two conveyor belts 33 and at least one of the two transport rollers 34,35 is usually carried out at every third puncture, ie after completion of a Hohlsaumausnehmung A. The feed corresponds to the distance of the two axes of the engraver C, D and is about 4mm. Such a large hole spacing can not be produced with the known machines.

In the FIGS. 13, 14 and FIG. 18 shows how the inventive production of a hemstitch with a piercer C, in which a passage opening 27 for the at least one needle 8 is present, can also be used on a household sewing machine N2. As in the household sewing machine according FIG. 18 the needle 8 is fixed and pierces vertically into the fabric, the at least one engraver C is arranged at an acute angle to the needle axis V ₁ . Since in a household sewing machine no drive device for a engraver C is provided and also in the area laterally the needle bar is not enough space for such a drive is present invention the engraver drive housed in a separate, attachable to the sewing machine N2 housing 51. The housing 51 is suitably releasably attached to the lower, rear or front side of the upper arm 53 of the sewing machine. In the housing 51 is a drive element, such as a linear motor, a crank mechanism or the like, arranged with which the engraver C at an acute angle to the axis V _{1 of} the needle 8 in the fabric pierceable and retractable. Usually, three pinholes are made per puncture of the engraver C. This means that the engraver only needs to penetrate the needle into the material at every second puncture of the needle 8 and then has to be pulled out of it again. In the drive housing 51, a controller can be accommodated in addition to the linear drive, which, connected to the sewing machine via a cable not visible in the figures or a plug controls the movement of the engraver C. In addition to the engraver C, which is mounted in the drive housing 51, a somewhat larger recess 18 must be provided in a needle sewing machine in the throat plate so that the engraver C can penetrate the needle plate 21 before piercing the needle.
In FIG. 13 the engraver C has already penetrated the throat plate 21 and also the needle 8 is driven vertically from above through the recess 27 in the engraver. FIG. 14 shows the engraver C and the needle 8 in optimally retracted position, for example, before the fabric is pushed under the needle 8 and the engraver C or when the fabric is advanced by the feed dog.

Claims (9)

1. A sewing machine with at least one needle (8) for creating a hemstitch in a material to be sewn (1), as well as with a transporter (31) for the transport of the material to be sewn, wherein the axis (V₁) of the at least one needle (8) runs at an acute angle (α) to the axis (Y) of a piercer (C), and the needle (8) may be driven by a needle rod drive in the direction of the axis (V₁) and the piercer (C) by a piercer bar drive in the direction of the axis (Y) of the piercer (C), characterised in that the at least one piercer (C), seen in the sewing direction (5), is arranged laterally of the needle, and comprises a slot (27) extending in the piercer (C) or at least one groove (28) incorporated peripherally on the piercer (C), through which slot or groove the at least one needle (8) may be led within the piercer cross section, on stitch formation with a pierced piercer (C).
2. A sewing machine according to claim 1, characterised in that two needles (8, 9) are arranged axially symmetrical to the piercer (C) lying in a V-shape, and cross in the slot (27) in the piercer (C) or in the lateral grooves (28), within the piercer cross section, on stitch formation.
3. A sewing machine according to claim 2, characterised in that in each case a slot (27) for one of the two needles (8, 98), or a common slot (27) for both needles (8, 9) or in each case a groove (28) for both needles (8, 9), is formed in the piercer (C).
4. A sewing machine according to one of the claims 1 to 3, characterised in that the needle axis (V₁, V₂) with the at least one needle (8, 9) is pivotally or slidably mounted for changing the stitch insert location.
5. A sewing machine according to one of the claims 1 to 4, characterised in that the angle (α) between the axis (V₁, V₂) of the needle (8, 9) and the axis of the piercer (C) is approx. 30°.
6. A sewing machine according to one of the claims 1 to 5, characterised in that the transporter (31) comprises two drivable transport belts (33) which revolve in parallel and whose belt face lying at the top projects beyond the * (21) and/or that at least one drivable transport wheel (34, 35) is arranged, which cooperates with a counter holding wheel on the presser foot on sewing, and in a clamped manner, transports the material to be sewn.
7. A sewing machine according to claim 6, characterised in that the transport belts (33) and/or the at least one transport wheel (34, 35) have a freewheel.
8. A sewing machine according to one of the claims 2 to 7, characterised in that the two grippers (24, 25) revolve or oscillate on rotation axes arrange parallel to the * (21), and that the rotation axes (28, 29) lie parallel to the sewing direction (5).
9. A piercer for a sewing machine according to one of the preceding claims, characterised in that the drive element for the at least one piercer (C) is accommodated in a separate housing which may be fastened on the sewing machine, and is connectable to the control and feed of the sewing machine, and that the piercer axis (Y) lies at an acute angle to the * (21) of the sewing machine, and may be driven in coordination with the needle drive.

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