EP1052324B1 - Sewing machine needle with offset eye lips - Google Patents

Description

The invention relates to a sewing machine needle, in particular for high-speed sewing machines.

Stitch numbers of 5000 stitches / min and more are the norm in industrial sewing machines today. In certain applications, even up to 8000 stitches / min and more are achieved.

When the needle is inserted into the sewing material, it opens a stitch hole and pulls the thread (sewing thread) into the needle hole one. At very high number of stitches, a very small time span of approximately 0.5 ms or less is available for opening the needle hole. The taphole opening time is the duration from the first contact of the material through the needle point to the Öhrdurchgang. The almost explosive opening of the needle hole causes high frictional forces between the sewing machine needle and the material to be sewn. Therefore, relatively large puncture forces may be required, which increases the energy required for the needle puncture.

Due to the high frictional force between the needle and the sewing material, heat is generated when opening the needle hole, which can cause thermal damage to the material. For example. Synthetic fibers can be melted or melted in the puncture area. In addition, fibers or fiber assemblies can be mechanically damaged by the explosive opening of the stitch hole. Another consequence is frequently occurring sewing thread breaks.

In addition, depending on the material to be sewn, the sewing production can be hindered by the smearing of laminates and coatings as well as of paint or equipment components. These problems can lead to a significantly reduced seam quality and impaired wearing properties in ready-made textiles.

This leads to a desire to reduce the size of stitchholes. However, this finds its limit in the sewing thread thickness specified in most cases and the size of the sewing machine needles required to guide the sewing thread. A certain sewing thread thickness sets a certain Minimum needle size ahead. In addition, the size of the eye of the needle increases analogously to the needle size.

Another problem associated with sewing needles is the mechanical stress on the sewing needle, especially at higher machine speeds. Rotating masses in the sewing machine can cause vibrations, which in particular have an effect on the sewing machine needle clamped on one side. In addition, acting on the needle, as a result of thread tension and deflection when hitting the sewing machine needle on the fabric and as a result of operating influences further forces. This in turn leads to the desire to use as thick sewing machine needles that have a sufficient rigidity. Both requirements, to use as thin a sewing machine needle to protect the fabric and to avoid excessive needle heating and to use the thickest possible sewing machine needle to achieve the required stability at high sewing speeds, contradict each other.

From US-PS 4,037,641 a sewing machine needle with a straight shaft is known, which has in the vicinity of its tip a transverse to its central axis through eye. The eye is bounded in the axial direction by two opposing Öhrstege, both of which lie substantially on the central axis of the sewing machine needle. A thread trench joins the eye in the direction of the clamping part of the shaft. On the opposite side of the sewing machine needle, another short groove is provided, which runs in the direction of the needle tip and runs flat in the immediate vicinity of the eye. On the same side of the sewing machine needle closes to the eye in the direction of the chucking towards a groove at. The Öhrsteg arranged between the thread groove and the groove is rounded on the tube side and serves to retract the thread in an opened tap hole.

Due to the approximately central arrangement of the Öhrstegs with respect to the shaft of the thread runs during insertion into the fabric on one side of the sewing machine needle in the yarn channel, while he finds on the other side of the sewing machine needle substantially into the groove. The eye region of the sewing machine needle is dimensioned transversely to the central axis and in the opening direction of the eye so that the open hole is relatively large. This results in the above relationships.

If the sewing machine needle is pulled out of the sewing material in a return stroke, the thread leading through the eye runs on an S-curve through the eye. Here existing friction leads to corresponding forces between the sewing machine needle and the thread and to a corresponding heating.

From DE 30 27 534 a sewing machine needle with a straight shaft is known through which passes through an eye. Both to the needle tip and to the Einspannteil out the eye is bounded by an Öhrsteg. Both Österstege lie on a common center line of the sewing machine needle. The same document discloses a further embodiment of a sewing machine needle with a cranked shaft from the Schaftkröpfung results in a small lateral offset of the Öhrstege against each other. However, the Nadelkröpfung leads to increased friction with the seam and thus to heat the same, especially at higher stitch counts.

From EP-A-0 882 831 tufting needles with a flattened needle body and a transverse eye are known. The needle body is straight and the Österstege are offset from the central axis of the needle body. However, tufting needles are generally not suitable as sewing machine needles. They are held in groups on a common carrier body, which is connected to a barre of a tufting machine. The tufting needles pierce in a relatively slow common mode the so-called backing for the production of a carpet. Tufting needles are neither intended nor suitable for creating sutures.

It is an object of the invention to improve the sewing machine needle in terms of reducing their heating.

This object is achieved with a sewing machine needle having the features of claim 1:

The sewing machine needle according to the invention has a substantially straight shaft. This has no offset area in which parts of the shaft could protrude laterally beyond its unattenuated contour. This makes it possible for the sewing machine needle, which penetrates into the sewing material, to not laterally deflect the flanks of the stitch hole that is produced, as a result of which an acceleration of the sewing material in the lateral direction and any resulting friction is avoided.

The sewing machine needle according to the invention has two spaced-apart Österstege, which are offset from the central axis of the sewing machine needle. The offset is preferably such that the pointing to the Einspannteil Öhrsteg releases a barrier-free transition into the eye. He is thus arranged on the side facing away from the thread groove of the sewing machine needle. In contrast, the Öhrsteg pointing to the tip of the sewing machine needle is offset straight to the other side of the eye. It is arranged approximately in imaginary extension of the thread trough. Overall, these measures allow a reduced friction of the thread on the sewing machine needle and a reduced friction of the sewing machine needle during insertion into the sewing material. The offset of the Österstege against each other allows a reduction in the height of the sewing machine needle in Öhrbereich compared to the nominal size of the sewing machine needle without any fundamental loss in terms of needle stiffness. The height of the sewing machine needle is measured perpendicular to the central axis and in a direction leading through the eye direction.

The reduction of the friction of the sewing machine needle with the sewing material occurs in particular when piercing the sewing machine needle in the fabric in appearance. During the return stroke, the offset of the Öhrstege allows a low-deflection threadline in the area of the eye, so that in turn there is no excessive friction.

Overall, this results in a lower puncturing force, which leads to a lower power requirement for driving the sewing machine needle. In addition, the recorded needle warming due to the reduced friction is lower. At the same time results in a material-friendly tap hole opening at the same time high thread protection. The probability of missing stitches and thread breakage is significantly reduced.

In an advantageous embodiment of the invention, the Österstege are rounded and edgeless formed, the rounding of the upper, i. preferably has a radius of 20% of the nominal needle gauge to the chuck portion indicative ear stub at a desired eye chord thickness of 50% of the nominal needle gauge. Overall, this leads to a good yarn path.

The Österstege are preferably offset from each other by a distance transverse to the central axis, which is at least 40% to a maximum of 50% of the nominal needle thickness. As a result, the thread guard can be optimized in the extended longitudinal passage of the thread through the eye.

The Österstege are preferably about half as thick as the nominal nominal thickness of the sewing machine needle. This results in both the possibility of a slim design of the sewing machine needle in Öhrbereich, as well as a good stability and rigidity.

The tip of the sewing machine needle can lie on a central axis which at the same time leads approximately centrally through the eye. If necessary, however, the tip of the sewing machine needle can also be offset relative to the central axis. Regardless, it is expedient to arrange the Österstege such that an imaginary, passing through the eye and fitting to the inner surfaces of Öststegen straight with the central axis forms an acute angle, which is smaller than 20 °. The Öhrstegversatz and at the same time the low acute angle of the thus defined, passing through the Öststeg tangent allow low friction of the thread on the sewing machine needle, even if the eye in the axial direction (direction of the central axis) is relatively narrow.

The friction can be reduced here by a concave design of Öhrstege.

The sewing machine needle preferably has a relatively short eye, in which the distance between the eye webs measured in the axial direction is about one to 1.1 times as large as the nominal needle thickness. This results in a precise guidance of the thread and may possibly lead to a reduction in the required penetration depth.

The eye walls preferably have non-planar walls on the side, with the eye walls diverge towards both eye openings. In addition, the angle trapped between the eye walls and measured transverse to the central axis may vary along the central axis. This favors the passage of the thread through the eye and reduces its friction. At the same time the two-sided support of the thread loop required for Stichverschlingung is ensured.

In the vicinity of the eye, a groove can be provided on a side of the sewing machine needle facing away from the thread groove. The groove is preferably without sharp edge in the eye, which is useful for the thread guard.

A preferred embodiment of the sewing machine needle has eye walls, which do not protrude beyond the Öhrsteg pointing towards the Einspannteil. This results in a relatively small needle cross-section in the transverse region and a comparatively slow opening of the stitch hole and a corresponding protection of the fabric.

Further details of advantageous embodiments of the invention can be taken from the drawing or the description and / or subject matter of the subclaims.

• Fig. 1 eine Nähmaschinennadel mit einem gestreckt durch das Öhr laufenden Faden, in längsgeschnittener, ausschnittsweiser und vereinfachter Darstellung,
• Fig. 2 die Nähmaschinennadel nach Figur 1, geschnitten entlang der Schnittlinie II-II in Figur 1, ohne Faden,
• Fig. 3 die Nähmaschinennadel nach Figur 1, geschnitten entlang der Schnittlinie III-III in Figur 1, ohne Faden
• Fig. 4 die Nähmaschinennadel nach Figur 1, mit einem durch das Öhr laufenden Faden beim Einstichvorgang, in längsgeschnittener, schematisierter und ausschnittsweiser Darstellung,
• Fig. 5 die Nähmaschinennadel nach Figur 1, mit einem durch das Öhr laufenden Faden, nach dem Einstichvorgang zu Beginn des Rückhubs, in längsgeschnittener, schematisierter und ausschnittsweisen Darstellung, und
• Fig. 6 die Nähmaschinennadel nach Figur 1, mit einen durch das Öhr laufenden Faden, beim Rückhub, mit ideal ausgebildeter Fadenschlinge zur Aufnahme durch den Schlingenfänger in längsgeschnittener, schematisierter und ausschnittsweiser Darstellung.

In the drawing, an embodiment of the invention is illustrated. Show it:

• 1 is a sewing machine needle with a thread running through the eye, in longitudinal section, fragmentary and simplified representation,
• 2 the sewing machine needle according to FIG. 1, cut along the section line II-II in FIG. 1, without thread, FIG.
• Fig. 3, the sewing machine needle of Figure 1, taken along the section line III-III in Figure 1, without thread
• 4 shows the sewing machine needle according to FIG. 1, with a thread running through the eye during the insertion process, in a longitudinally sectioned, schematized and fragmentary illustration, FIG.
• 5 shows the sewing machine needle according to FIG. 1, with a thread running through the eye, after the insertion process at the beginning of the return stroke, in a longitudinally sectioned, schematized and fragmentary illustration, and FIG
• Fig. 6 shows the sewing machine needle of Figure 1, with a current through the eye thread, the return stroke, with ideally trained thread loop for receiving by the loop catcher in longitudinal section, schematized and fragmentary representation.

FIG. 1 illustrates a sewing machine needle 1 whose shaft 2 extends from a clamping part (not illustrated in FIG. 1) and adjoining the shaft 2 on the left to a point 3 along a central axis 4. The tip 3 is preferably on the central axis 4. The shaft 2 is, as illustrated in FIG. 3, formed substantially flattened on its upper side 5 in the figure and on its lower side 6. Between the side 5 and the side 6 arranged side surfaces 7, 8 are convex. The cross section of the sewing machine needle 1 is approximately square in this region of the unattenuated shaft 2, apart from the convex curvature of the side surfaces 7, 8. The nominal needle thickness is determined in the shaft region above the groove in the direction of the clamping part by the diameter of the sewing machine needle 1.

Not too far away from the tip 3, an eye 11 is arranged, which leads transversely to the central axis 4 through the shaft 2 and which can be seen in FIGS. 1 and 2. The height of the eye 11 is determined by the distance of the sides 5 and 6 to each other. In this area (eye 11), the sewing machine needle 1 is preferably somewhat weaker than in the unattenuated area of the shaft 2, which is shown on the left in FIG. The reduction in the thickness of the shaft 2 in the eye region is in the exemplary embodiment at about 5% to 20%, preferably about 10% with respect to the distance between the side 5 and the side 6 in the unattenuated area.

The eye 11 is bounded in the axial direction indicated by the central axis 4 by two Öhrstege 12, 14, which are offset from the central axis 4 in the direction of the thread protection groove 21 or groove 34. At their end facing the eyelet 11, the Österstege 12, 14 are rounded in each case approximately semicircular, wherein the rounding radius respectively corresponds to exactly half the thickness of each Öhrstegs 12, 14. The offset between the two eye webs 12, 14 measured vertically in the transverse direction, ie in FIG. 1, is preferably about 40% to 50% of the nominal needle thickness. Thus, the Öhrstege 12, 14 with their bottom surfaces 16, 17 each approximately at the central axis 4. The rounded ear-side end of Öhrstegs 12 goes from its circular arc shape at a point 15 kink and paragraph free in a stretched and, as shown in Figure 1, with respect to the central axis 4 concave curved bottom surface 16 via. At the transition region between the bottom surface 16 and the rounded end of Öhrstegs 12, a tangent can be applied, which lies on the central axis 4 or with this includes a very acute angle of a few degrees.

The same applies to the Öhrsteg 14, which also has a concave rounded yarn running side bottom surface 17. A transition point 18 between the bottom surface 17 and the rounded end of the Öhrstegs 14 lies approximately on the central axis 4 and a tangent to this point is approximately equal to the central axis 4. An as flat as possible guided by the eye 11 straight line, which rests as a tangent at suitable locations of the bottom surfaces 16, 17 thus includes with the central axis 4 an acute angle in the range of a few degrees, preferably less than 20 °.

The eye 11 is relatively narrow. In the axial direction, which is determined by the central axis 4, is the by the axial distance of the ends of Öststege 12, 14 certain length of the eye preferably about 1 to 1.1 times the nominal needle thickness of the sewing machine needle 1. This allows a good thread guide. Despite the thus relatively short eyelet 11 is due to the offset of the Öhrstege 12, 14 reaches a stretched yarn path. Embodiments are also possible in which the length of the ear may be greater or less than 1 to 1.1 times the nominal needle size.

Following the eyelet 11, a thread groove 21 is formed along the side 6, directed away from the tip 3, which is delimited by two side walls 22, 23 (FIG. 3). These have two substantially planar, mutually parallel flanks, which are partially touched to the side 6 out. The thread groove 21 also has a substantially planar bottom 24 which extends at some distance parallel to the central axis 4. In a distance approximately corresponding to the needle size from the eye 11, the base 24 then begins to transition into the bottom surface 16 of the Öststegs 12. The bottom surface 16 then runs at an acute angle to the central axis 4.

The eyelet 11 is, as is apparent in particular from Figure 2, bounded by two Öhrwänden 26, 27 whose thickness, measured transversely to the eyelet 11 (Figure 2, line 28), each slightly smaller than the inside diameter of the eye in the region of this passing through the central axis 4 line 28. The flanks of the thread groove 21 go with the confluence of the thread groove 21 in the eye 11 seamlessly in inner surfaces 29, 30 of Öhrwände 26, 27 via. In this case, between the flanks of the thread groove 21 and the inner surfaces 29, 30 enclosed, measured transversely to the central axis 4 angle change along the central axis 4. While the flanks of the thread groove 21 in the region of the cross section III-III (Figure 3) are parallel to each other, the inner walls 29, 30 in the region of the section line II-II (Figure 2) are arranged at an acute angle to each other. However, the inner surfaces 29, 30 also diverge from one another in the lower and upper side in FIGS. 1 and 2, so that the eyelet 11 is waisted. Starting from the eyelet 11, a short, flat leaking groove 32 extends to the top 3, but without reaching them. The groove 32 bounded by the bottom surface 17 ends, starting from the eye 11, approximately midway in front of the tip 3. In this region, the sewing machine needle has an approximately circular, weakened cross section. This cross section decreases conically in the direction of the tip 3.

At the side of the eyelet 11 remote from the tip 3, a groove 34 is provided in the shaft 2. This lies opposite the yarn channel 21. The groove 34 has a visible from Figure 3, rounded and rounded in the side surfaces 7, 8 merging back 35. The rounded transitions serve to relieve and protect the seam material. 1 is a transition region 36 from the groove 34 to the eyelet 11. The transition region 36 is formed by the Öhrsteg 12, wherein the transition from its rounded end to the outside is formed edge-free. From the transition point of the rounded end of Öhrstegs 12 to the outside or side 5 of the sewing machine needle 1, the eye walls 26, 27 extend at the same height, without projecting laterally or in Figure 1 above the Öhrsteg 12. While the lower end of the eyelet 11 in Figure 1 at the same height with the entire side 6 of the sewing machine needle. 1 is located, the upper end of the eyelet 11 is located slightly lower than the side 5 at least, in the unattenuated shaft region. In other words, the height of the eye walls 26, 27 to be measured parallel to the line 9 shown in FIG. 2 is slightly less than the nominal needle thickness.

The sewing machine needle 1 described so far operates as follows:

Sewing machine needle 1 is oscillated reciprocally during sewing in rapid succession along its central axis 4. If the sewing machine needle 1 initially moves away from a sewing material arranged approximately in front of its tip 3 at right angles to the central axis 4, a thread 38 (sewing thread) running through the eyelet 11 is first stretched out through the thread groove 21 and the groove 32. The thread 38 is under tension, so that it is selectively applied to the bottom surfaces 16, 17 of Öhrstege 12, 14. Due to their concave design a planar system is avoided.

If the sewing machine needle 1 now reverses its direction of movement and punctures the sewing material, the state illustrated in FIG. 4 is reached. The tip 3 opens here in fractions of a millisecond a stitch hole, in which the sewing machine needle 1 penetrates to her eyelet 11 by widening the stitch hole. The expansion takes place relatively gradually, whereby the friction between the sewing machine needle 1 and the fabric is reduced to a tolerable level even at high sewing speeds (stitch counts).

The sewing machine needle 1 is stung with the eye 11 through the sewing material, the thread 38 is placed around the Öhrsteg 12. The upper section of the thread 38 in FIG. 4 has only a slight relative speed with respect to the sewing material and is more or less at rest. The advancing sewing machine needle 1 pulls, as indicated in Figure 4 by arrows, the lying in the yarn groove 21 portion of the thread 38 at very high speed. Too much friction between the yarn 38 and the fabric is largely minimized by the considerable depth of the yarn groove 21. Too much friction on the ear land 12 is minimized by its roundness and considerable thickness, e.g. approximately coincides with the diameter of the thread 38.

In the further course of the sewing process, the sewing machine needle 1 reverses its direction of movement, as illustrated in FIG. The pierced by the sewing machine needle 1 in the sewing thread 38 now lifts off the Öhrsteg 12 from. There remains a first still standing in the eye 11 loop, which is urged by the in Fig. 5 with the sewing machine needle 1 to the left moving Öhrsteg 14 from the eye 11 in the desired direction (Figure 5 vertically upward). This is illustrated in FIG. A loop 39 forms, which can be picked up by a gripper 40 for seam formation. The exact design of this sling is crucial for a functioning sewing process. The sewing machine needle 1 then goes through the puncture hole in the return stroke. The thread is withdrawn at high speed to wrap the bobbin case in the opposite direction of the needle movement. Is the sewing machine needle 1 out of the stitch hole and the thread 38 tightened, the process is repeated again.

The sewing machine needle 1 has a in the axial direction of two Öhrstegen 12, 14 limited eye 11, which is relatively short in the axial direction (central axis 4). Its length is not significantly greater than the nominal thickness of the sewing machine needle 1. The Öhrstege 12, 14 are offset from each other, each Öststeg 12, 14 is about half as thick as the sewing machine needle 1 in the eyelet 11. Thus, a stable and slender Sewing machine needle 1 created that opens relatively slowly due to their slimming puncture holes and thus gently sews even at very high stitch counts, while allowing a nearly fully protected threadline.

Claims (12)

1. Sewing machine needle (1),
   with a substantially straight blade (2), which adjoins a clamping part, extends along a central axis (4) and ends in a point (3),
   with a thread groove (21), which has a substantially plane base (24) running at some distance parallel to the central axis (4) and which has a substantial depth to receive the thread and minimise friction between the thread (38) and the material to be sewn,
   with an eyelet (11), which is defined by two eyelet webs (12, 14), which are spaced from one another in the direction of the central axis (4) and are staggered relative to one another transversely (9) to the central axis (4),
   characterised in that
   respectively measured transversely to the central axis (4) the eyelet webs (12, 14) have a thickness, which amounts to at least 40% of the nominal needle thickness, and the eyelet webs (12, 14) lie on the central axis (4) with a respective transition region (15, 18) between their front, preferably rounded, end and a base surface (16, 17) on the thread side,
   wherein the eyelet web (14) facing the point (3) is arranged approximately in an imaginary extension of the thread groove (21).
2. Sewing machine needle according to Claim 1, characterised in that the eyelet webs (12, 14) are rounded, wherein their radius of curvature is preferably equal to half the thickness of the eyelet web (12, 14).
3. Sewing machine needle according to Claim 1, characterised in that the eyelet webs (12, 14) are staggered relative to one another transversely to the central axis (4) at a distance, which amounts to at least 40%, preferably 50%, of the nominal needle thickness.
4. Sewing machine needle according to Claim 1, characterised in that respectively measured transversely to the central axis (4), the eyelet webs (12, 14) have a thickness, which amounts to 50% of the nominal needle thickness.
5. Sewing machine needle according to Claim 1, characterised in that the arrangement and configuration of the eyelet webs (12, 14) are such that an imaginary straight line passing through the eyelet (11) and abutting against the base surfaces (16, 17) of the eyelet webs (12, 14) on the thread side encloses an acute angle with the central axis (4), which is smaller than 20°.
6. Sewing machine needle according to Claim 1, characterised in that the eyelet webs (12, 14) respectively have a base surface (16, 17) on the thread side,
   wherein at least one base surface, preferably both base surfaces (16, 17) are concave.
7. Sewing machine needle according to Claim 1, characterised in that the length of the eyelet (11) measured in the direction of the central axis (4) is smaller than twice the nominal needle thickness.
8. Sewing machine needle according to Claim 1, characterised in that the length of the eyelet (11) measured in the direction of the central axis (4) is 1- to 1.1-times the nominal needle thickness.
9. Sewing machine needle according to Claim 1, characterised in that each eyelet web (12, 14) defines a thread groove (21, 32) with its base surface on the thread side.
10. Sewing machine needle according to Claim 1, characterised in that the eyelet walls (26, 27) have inside faces (29, 30), which at axially spaced locations enclose different angles with one another.
11. Sewing machine needle according to Claim 1, characterised in that the height of the sewing machine needle (1) measured at the eyelet (11) perpendicular to the central axis (4) in a direction (9) leading through the eyelet (11) is less than the needle thickness.
12. Sewing machine needle according to Claim 1, characterised in that adjoining the eyelet web (12) facing towards the clamping part, the eyelet (11) has eyelet walls (26, 27), which do not project laterally over the eyelet web (12).

Images