EP1052323B1 - Needle for sewing machine with slender eye - Google Patents

Description

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

In industrial sewing today, machine speeds are (Number of stitches / min) of 5000 stitches / min the rule. In some applications, even 8000 stitches / min and achieved more.

When sewing, the sewing machine needle sticks through the material, creating a tap hole. The one to open the taphole The time available is the duration from the first Touch of the sewing material through the needle tip up to the eye passage. This taphole opening time is on one Lockstitch machine at 5000 stitches / min approx. 0.5 ms. The opening the taphole goes with a quick, almost explosive lateral displacement of the material. This leads to high frictional forces and thus high required ones Puncture forces as well as a high one, for sewing required, power requirement.

If the number of stitches is very high, the sewing material can be mechanical and also be thermally damaged. It is possible that Fibers or fiber associations (yarns) at the taphole opening be blown up. In addition, the high frictional forces cause a temperature rise on the needle that is inside the melting range of conventional synthetic fibers in just a few seconds reached. Such fibers are then or in the puncture area melted. Another consequence are common ones Nähzwirnbrüche.

The melting of laminates and coatings as well of color or equipment components can go to others Disabilities when sewing. The problems mentioned can lead to reduced seam quality and wearing properties made-up textiles.

In addition, the sewing machine needles are subject in particular relatively high at high machine speeds mechanical loads. Increasing machine speeds cause increasing dynamic problems. In masses rotating on the sewing machine can cause vibrations, which particularly relate to the one-sided Impact sewing machine needles. These must also external forces, such as thread tension, deflections when Impact on the sewing material as well as operational influences, grown his. Are therefore used to increase stability Thicker needles are used, but the ones above will tighten problems mentioned.

When sewing, the sewing thread is removed from the sewing machine needle pierced through the material. In this process, the Protect sewing thread from damage. That is why When industrial sewing, the sewing machine needle even at extreme changing speeds Sewing thread runs almost smoothly throughout Stitch formation cycle enabled. After the sewing thread thickness in in most cases for reasons of the desired seam strength is specified, the sewing machine needle must Sewing thread of specified strength also in the high-speed range with low friction and sufficient sewing thread protect. It is also important to have too much movement friction between sewing thread and material at high speed to avoid. If this cannot be guaranteed, comes uncontrollable thread breaks and skipped stitches.

From DE 3027534 A1 a sewing machine needle is included laterally bent shaft known. Along the shaft is a thread groove that leads to an eye that is located near the tip of the sewing machine needle. The thread gutter is delimited by two side walls, which are extend into the eye area. In the transition from the over the thread groove leading to the side of the shaft the needle contour follows up to the needle tip Essentially a straight line.

This document also discloses a sewing machine needle with cranked shaft. An end to the bend immediately follows the eye. In this area the eye walls are slightly behind on an opening side of the eye arched inside. However, the thickness of the needle also increases this embodiment from the top to beyond the eye always closed.

The high speed sewing problems described above can occur on this sewing machine needle.

Based on this, it is an object of the invention to provide an improved sewing machine needles suitable for high working speeds to accomplish.

The task is solved with a sewing machine needle, which has the features of claim 1.

The sewing machine needle according to the invention has a reduced one Cross-sectional ear volume with constant eye width and at the same time improved thread protection features on. This must give a stitch hole for a sewing thread Strength can be opened less wide, so that friction effects the sewing machine needle and the material to be sewn. The Cross-sectional reduction of the eye is due to a channel-side Indentation reached. The eye width is thereby not negatively affected, making sewing threads more conventional or given strength can be used.

The indentation changes the characteristic of the puncture force curve. The first peak of power that comes through the eye passage a normal needle is usually dominant significantly reduced. The maximum tap hole expansion takes place comparatively gentle only when the upper one penetrates Needle shaft, i.e. if the lowering movement of the needle is slower and goes to zero. The explosive effect at the normal needle due to the maximum tap hole expansion highest penetration speed occurs is minimized or prevented.

There is advantageously a lower puncture force and thus a reduced power requirement for the sewing process with low needle heating and a taphole opening that is gentle on the material. Besides, that can Eye designed so that there is a high thread protection results in fewer missing stitches and fewer thread breaks happen.

The indentation is preferably dimensioned such that the Eye walls have a total height at at least one point, which is slightly less than the height of one between the Tip and eye area. This makes it possible the widening from the top to the eye the sewing machine needle by a simultaneous slight Flattening a little bit and therefore only one overall to achieve slow increase in needle cross-section. This reinforces the advantages mentioned above.

In an advantageous embodiment of the invention shows the sewing machine needle at least in a certain Area of the eye a substantially constant total height on, which also delays the opening movement when Grooving helps.

The indentation of the sewing machine needle points at one advantageous embodiment an essentially constant Radius, with the center of curvature approximately at height the eye can be arranged. The radius is preferred dimensioned relatively large and is advantageous Fall about 3 to 4 times the nominal needle size. This is to be determined in an un weakened shaft area.

While the sewing machine needle according to the invention with the thread channel side an indentation on the eye the eye walls are on the opposite side of the eye preferably straight, here too there is no or almost no protrusion from the eye.

The wall thickness within an eye wall can vary from one Vary side of the eye to the other. For example. it is considered viewed advantageously, the eye walls at their the indentation to form the adjacent side with a slightly thicker wall than on their side away from the indentation. The side faces the sewing machine needle can be parallel to the central axis and in the transverse direction an acute angle be arranged including each other.

A particularly advantageous embodiment of the invention Sewing machine needle has a thread groove, which extends with undiminished height into the eye area, however, the height of the thread gutter limiting Walls along the entire gutter, especially up to to the eye and to the bulge formed in the eye area, is constant. This enables maximum thread protection with a very lean training of the Öhrs and thus low puncture forces and slow tap hole expansion.

The shaft of the sewing machine needle is preferably with provided a lateral bend, that on the thread groove side of the sewing machine needle a groove sets. The fillet creates space for a thread gripper, which comes into contact with the sewing thread during seam formation.

In a preferred embodiment, the height is walls bounding the thread groove in the transition to the eye slightly enlarged, which can improve the thread protection even more.

In the axial direction, i.e. along the central axis that is Öhr preferably limited by Öhrstege, the rounded trained and arranged offset against the central axis are. The curvature of the eye bridges is dimensioned so that the ends of the eye bridges are semicircular. Here are the rounding axes the eye bridges against each other by about half the eye height added. The arrangement is preferably such that a tangent running through the eye with the Central axis encloses an angle, which is preferably clear is less than 20 °. A stretched through the eye Thread with a thickness that corresponds to the strength of the used Sewing thread corresponds to, closes with the central axis preferably also an angle that is smaller than 20 °.

Fig. 1 eine erfindungsgemäße Nähmaschinennadel in längsgeschnittener, ausschnittsweiser und schematisierter Darstellung,

Fig. 2 die Nähmaschinennadel nach Figur 1, geschnitten entlang der Linie II-II in Figur 1,

Fig. 3 die Nähmaschinennadel nach Figur 1, geschnitten entlang der Linie III-III in Figur 1,

Fig. 4 die Nähmaschinennadel nach Figur 1, geschnitten entlang der Schnittlinie IV-IV in Figur 1,

Fig. 5 die Nähmaschinennadel nach Figur 1, geschnitten entlang der Schnittlinie V-V in Figur 1,

Fig. 6 die Nähmaschinennadel nach Figur 1, mit einem durch ihr Öhr geführten Faden vor dem Einstichvorgang, in längsgeschnittener, ausschnittsweiser und vereinfachter Darstellung,

Fig. 7 die Nähmaschinennadel nach Figur 1, mit einem durch ihr Öhr geführten Faden bei Einstichvorgang, in längsgeschnittener, ausschnittsweiser und vereinfachter Darstellung,

Fig. 8 die Nähmaschinennadel nach Figur 1, mit einem durch ihr Öhr geführten Faden während des Einstichvorgangs kurz nach Bewegungsumkehr beim Zurückziehen der Nadel, in längsgeschnittener, ausschnittsweiser und vereinfachter Darstellung, und

Fig. 9 die Nähmaschinennadel nach Figur 1, mit einem durch ihr Öhr geführten Faden im Rückhub mit ideal ausgebildeter Fadenschlinge zur Aufnahme durch den Schlingenfänger, in längsgeschnittener, ausschnittsweise und vereinfachter Darstellung.

Further details of advantageous embodiments of the invention are the subject of dependent claims, the drawing or the description. An exemplary embodiment of the invention is illustrated in the drawing. Show it:

1 shows a sewing machine needle according to the invention in a longitudinally cut, partial and schematic representation,

2 shows the sewing machine needle according to FIG. 1, cut along the line II-II in FIG. 1,

3 shows the sewing machine needle according to FIG. 1, cut along the line III-III in FIG. 1,

4 shows the sewing machine needle according to FIG. 1, cut along the section line IV-IV in FIG. 1,

5 shows the sewing machine needle according to FIG. 1, cut along the section line VV in FIG. 1,

6 shows the sewing machine needle according to FIG. 1, with a thread passed through its eye before the puncturing process, in a longitudinally cut, fragmentary and simplified representation,

7 shows the sewing machine needle according to FIG. 1, with a thread passed through its eye during the pricking process, in a longitudinally sectioned, fragmentary and simplified representation,

8 shows the sewing machine needle according to FIG. 1, with a thread guided through its eye during the puncturing process shortly after reversal of movement when the needle is withdrawn, in a longitudinally sectioned, fragmentary and simplified representation, and

9 shows the sewing machine needle according to FIG. 1, with a thread guided through its eye in the return stroke with an ideally designed thread loop for reception by the loop catcher, in a longitudinally cut, partial and simplified representation.

A sewing machine needle 1 is cut out in FIG illustrated. It has a shaft 2 which in Figure 1 to the right in a tip 3. The shaft 2 defines a central axis 4, which runs through the tip 3. The shaft 2 does not extend further from one shown clamping part away, in a corresponding Attachment of a sewing machine.

The sewing machine needle 1 shows in Figure 1 on the left their shaft 2 one rounded on its upper side 5 and on their side surfaces 6, 7 flat cross section. The sewing machine needle 1 is on its lower side 8 a thread groove 9 provided by two side walls 10, 11 is limited. The side walls 10, 11 are polygonal limited or rounded to a channel bottom 12 over.

As can be seen from Figure 1, the thread channel extends 9 along the shaft 2 over an offset area 14 in which the shaft 2 is cranked, i.e. is bent out laterally. The offset area 14 lies on the Upper side 5 of the sewing machine needle 1 has a fillet 15 firmly. The back or saddle of the fillet 15 comes up at a short distance from the central axis 4. The Cross section of the sewing machine needle 1 results in this Area from Figure 3. As can be seen, the sewing machine needle 1 in the offset area 14 compared to that in FIG 2 illustrated area widened, but somewhat flatter educated. The cross sections of the shaft 2 in the Cross sections according to Figure 2 and Figure 3 are correct in area roughly match. They are about 12% smaller than that nominal cross-sectional area.

A transition area adjoins the offset area 14 17, in which the center of the cross section from a shifted position again close the central axis 4 or shifted to the same. The thread gutter 9 extends through the offset area and the Transition area 17 to an eye 18, which, as from Figure 1, located near the tip 3 is. The eye leads through the sewing machine needle in one direction 1, with the offset direction in the offset area 14 matches. Like the one illustrated in Figure 4 Cross section reveals the eye 18 of two eye walls 19, 20 delimited, between which a passage is trained. The eye walls 19, 20 are on their opposite inner surfaces 21, 22 essentially flat or slightly arched. The two inner surfaces 21, 22 are aligned approximately parallel to one another, while the outer sides 6, 7 here an acute angle include with each other. The eye walls 19, 20 point thereby a slightly larger on the thread channel 9 side Wall thickness than on that lying away from the thread groove 9 Page. The total cross section is up to 10% against the nominal needle size of the sewing machine needle in question 1 decreased.

In the transition area 17, an eye bridge 23 is formed, the end 24 of the eye 18 in the axial direction (direction the central axis 4) limited. The end 24 is with maximum possible radius rounded without edges. The gutter floor 12 of the thread runner 9 thus extends without edges to the end 24 of the Öhrstegs 23. The side walls 10, 11 of the thread groove 9 go from a first, in the Offset area 14, height H to be measured slightly increased height H1 above that in a parallel area 25 can be seen in which the thread groove 9 obliquely runs to the central axis 4.

Following the parallel area 25 are the side walls 10, 11 of the thread channel 9 into the eye walls 19, 20 passed. Here, i.e. in the area of the eye 18 are Eye walls 19, 20, as illustrated in Figure 1, with a Provide indentation 26 through which the lower, in Figure 1, Inlet of the eye 18 lying on the side of the thread groove 9 is offset towards the central axis 4. To the eye 18 is followed by a conical region 27 which is up to the top 3 leads. The largest to be measured at around 28 Radius of the conical region 27 is larger than that Distance of the inlet of the eye 18 in the region of the indentation 26 to the central axis 4. Thus the inlet of the Öhrs 18 offset against the conical region 27. The Indentation 26, as illustrated in FIG. 1, through a radius R starting from a center of curvature M set on the side of the thread groove 9 in Extension of the eye 18 can be found. The radius R is about four times the nominal needle size Nm.

Immediately following the indentation 26 follows a second eyelet 29, the eyelet at its end 30th is rounded. The Öhrsteg 29 runs on the of the indentation 26 remote side in a concave base 31 out. The sewing machine needle is for illustration 1 in Figure 5 cut along the section line V-V shown. The cross section is approximately round. At the The transition of the eye into the conical region 27 is the Cross-section somewhat flattened. The cross section is here against the cross-section that corresponds to the nominal needle size, reduced by about 20%.

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

6 shows the sewing machine needle 1 with a sewing thread 32 illustrates that led through the eye 18 is. It lies in the thread groove 9 and bends from it stretched through the eye 18. In the area of the concave bottom surface 31 it is hollow. The sewing machine needle 1 has not yet inserted into the material. It starts now move towards the sewing material and plunge into it. First, the tip 3 penetrates the material, after which by continued axial movement of the sewing machine needle 1 along its central axis 4 the conical area 27 enters the material and the stitch hole up to the eye 18 expands. The expansion takes place gradually and relatively evenly to a measure so that the sewing thread 32 can be pulled through the tap hole, making it around the Öhrsteg 23. This is illustrated in Figure 7. The sewing material glides over the Eye 18, passing through due to the height of the thread groove the parallel region 25 of that lying in the thread groove 9 Sewing thread 32 is kept away. This can be done with high take-off speed drawn into the tap hole without too much friction between the Sewing thread 32 and the sewing material comes. Especially in the ear area is the sewing thread 32 despite the slim eye design effectively protected. This is made possible by a combination the indentation 26 with a raised or lowered thread groove in the subsequent parallel area 25.

When the stitching process is finished, the sewing machine needle 1 withdrawn, with the sewing thread 32 initially takes the state illustrated in Figure 8. He solves extends from the eye bridge 23 and then, as illustrated in FIG. 9, a loop 33. The eye bridge 29 prevents thanks to its lateral offset against Öhrsteg 23 Exit of the sewing thread 32 in the direction of the thread groove. Rather, the sewing thread 32 is removed from the eye bridge 29 Eye 18 pushed out so that the desired loop sure forms. This noose will continue in the course of the sewing process by a gripper (not shown). The exact formation of this sling enables a flawless sewing process.

One especially for high working speeds The sewing machine needle 1 has a slender eye 18 on that directly into a running over the shaft Thread channel merges. This is on the side of the thread groove 9 Öhr provided with an indentation 26 that leads to a small Cross-section of the ear and thus to a low suture load leads during the puncturing process. In the transition area from the thread groove 9 to the eye 18, these are these Area bounding here measured from the bottom of the walls Thread channel so high that the sewing thread 32 does not expose and is thus effectively kept away from the sewing material.

Claims (14)

1. Sewing machine needle (1),
   with a blade (2), which adjoins a clamping part, extends along a central axis (4), at least in sections, and ends in a point (3),
   with an eye (18) opening transversely to the central axis (4), which is bordered by two spaced eye walls (19, 20) and is provided at least on one side with an indentation (26), at which the eye walls (19, 20) are lowered, at least in some regions, towards the central axis (4) relative to the direction of opening of the eye (18),
   wherein at least at one location (26) the eye walls (19, 20) have an overall height, which is less than the height of a region (27) lying between the point (3) and the eye (18).
2. Sewing machine needle according to Claim 1, characterised in that at least in one section of the indentation (26) of the eye (18), the eye walls (19, 20) have an essentially constant overall height, which increases adjoining this section.
3. Sewing machine needle according to Claim 1, characterised in that the indentation (26) has an essentially constant radius (R), wherein the centre of curvature (M) of the indentation (26) preferably lies in linear extension of the eye (18).
4. Sewing machine needle according to Claim 3, characterised in that the radius (R) is approximately equal to three-to four-times the nominal needle thickness (Nm).
5. Sewing machine needle according to Claim 1, characterised in that the eye walls (19, 20) terminate essentially linearly on their side opposite the indentation (26).
6. Sewing machine needle according to Claim 1, characterised in that the eye walls (19, 20) have a greater wall thickness on their side adjacent to the indentation (26) than on their side remote from the indentation (26).
7. Sewing machine needle according to Claim 1, characterised in that the blade (2) is provided with a thread groove (9), which opens into the eye (18) and, in the transition region between the thread groove (9) and the eye (18), the eye walls (19, 20) have a respective boundary, which is arranged parallel to the thread groove base present here and is preferably approximately linear in construction.
8. Sewing machine needle according to Claim 1, characterised in that the blade (2) has a furrow (5) and in the region of its furrow (15) has a lateral offset region (14).
9. Sewing machine needle according to Claim 1, characterised in that in the direction of the central axis (4), the eye (18) is bordered by eye webs (23, 29), which are rounded out, and their radius of curvature is preferably essentially equal to half the thickness of the eye web (23).
10. Sewing machine needle according to Claim 9, characterised in that the eye webs (23, 29) are offset relative to one another by a distance transversely to the central axis (4), which amounts to at least 40%, preferably 50%, of the nominal needle thickness (Nm), as measured in non-narrowed regions of the blade (2), and that the eye webs (23, 29) have a thickness, respectively measured transversely to the central axis (4), which amounts to at least 40%, preferably 50%, of the nominal needle thickness.
11. Sewing machine needle according to Claim 9, characterised in that the arrangement and configuration of the eye webs (23, 29) are such that an imaginary straight line passing through the eye (18) and abutting against the flanks of the eye webs (23, 29) on the thread side encloses an acute angle with the central axis (4), which is smaller than 20°.
12. Sewing machine needle according to Claim 9, characterised in that at least one (29) of the eye webs (23, 29) has a base surface (31) on the thread side, which is concave.
13. Sewing machine needle according to Claim 1, characterised in that the length of the eye (18) measured in the direction of the central axis (4) is smaller than double, preferably smaller than 1.5-times, the needle thickness measured in the region of the non-narrowed blade (2) transversely to the central axis (4).
14. Sewing machine needle according to Claim 1, characterised in that the height of the sewing machine needle (1), measured at the eye (18) transversely to the central axis (4) in a direction leading through the eye (18), is smaller than the nominal needle thickness (Nm).

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