EP1749917B1 - System for securing the needle thread after threading - Google Patents

Description

The invention relates to a device for securing the upper thread loop after threading according to the preamble of patent claim 1.

For decades, manually operated or fully automatic threading devices for threading the upper thread of a sewing machine through the eye of the sewing needle are known. When threading the upper thread is caught by means of a threading or fishing hook, which is guided through the eye of the needle, and formed a loop behind the needle eye. This thread loop can later be grasped by hand and the loose end pulled through the eye. In this manipulation there is a latent danger that upon detection of the relatively short, the needle eye superior loop or by a movement of the thread lever, the loop is pulled out of the needle eye again and thus the threading must be repeated.

To prevent this is out of the US 5,615,629 a threading device is known in which the yarn located in the threading or fishing hook is held clamped by a wire hanger. The upper thread is pressed from the wire hanger into the hook throat on the hook. Thus, the thread loop can be released for the sewing process, the wire hanger is led out with a backdrop of the hook when booting the threading device, after which the thread loop can fall off the fishing hook.

An object of the present invention is to provide a functionally reliable functionally reliable device for securing the upper thread loop after its formation by the Einfädelhaken.

This object is achieved by a device having the features of claim 1. Advantageous embodiments of the device are described in the dependent claims.

It succeeds with a fixed to the support and pivoting device for the threading hooks without the aid of a backdrop to secure the loop of thread during their formation by the threading hook, ie to prevent a dropping of the loop of thread before their complete training. The wire hanger is after the Threading and the upward driving of the threading hook outside the sewing area and is protected despite its filigree training from damage.

Figur 1

einen Vertikalschnitt durch die Schwenkvorrichtung mit dem Einfädelhaken unmittelbar vor Beginn des Einfädelvorgangs,

Figur 2

eine perspektivische Ansicht der Einfädelvorrichtung und der Nadel unmittelbar vor dem Einfädelvorgang,

Figur 3

einen Vertikalschnitt durch die Schwenkvorrichtung mit dem Einfädelhaken nach dem Fangen des Oberfadens,

Figur 4

eine perspektivische Ansicht der Einfädelvorrichtung und der Nadel nach dem Fangen des Oberfadens,

Figur 5

einen Vertikalschnitt durch die Einfädelvorrichtung mit ausgezogener Oberfadenschlaufe,

Figur 6

eine perspektivische Darstellung der Einfädelvorrichtung mit ausgezogener Oberfadenschlaufe und

Figuren 7a bis 7d

vier sich folgende Hakenstellungen während des Einfädelns des Oberfadens.

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

FIG. 1

a vertical section through the pivoting device with the threading hook immediately before the beginning of the threading process,

FIG. 2

a perspective view of the threading device and the needle immediately before the threading,

FIG. 3

a vertical section through the pivoting device with the Einfädelhaken after catching the upper thread,

FIG. 4

a perspective view of the threading device and the needle after catching the upper thread,

FIG. 5

a vertical section through the threading device with undressed needle thread loop,

FIG. 6

a perspective view of the threading device with undressed needle thread loop and

FIGS. 7a to 7d

four following hook positions during the Threading the upper thread.

With reference numeral 1, a support and pivot device 1 is designated. This is held pivotably about a vertical pivot axis in the upper arm of a sewing machine, not shown. The swivel device 1 is also in the vertical direction from a raised rest position (no Fig.) In a lowered threading position according to FIGS. 1 to 4 movably mounted. Further, in these figures with reference numeral 3, a needle with a needle eye, short eye 5, is shown. The needle 3 is in the raised position, ie the needle 3 does not dip into a material to be sewn (not shown). On the pivoting device 1 is a threading hook, short hook 7, attached. Whose the hook 7 forming front end 9 with the hook throat 10 (FIG. 7a Above the hook 7, a positioning device 11 is shown, which, guided by the needle 3, the hook 7 also positioned laterally exactly in front of the eye 5, regardless of the needle size and whether the needle 3 is perfectly straight or slightly bent. The hook 7 and the positioning device 11 are in the example described about a pivot axis S pivotally connected to the pivoting device 1.
On the pivoting device 1, a wire bracket 13 is further attached, which extends obliquely downwards Longitudinal leg 15 and an adjoining transverse to the needle 3 foot leg 17 comprises. In the example shown, the foot leg 17 is adjoined by a second longitudinal leg 19 lying parallel to the first longitudinal leg 15. The first longitudinal leg 15 may comprise at its upper end an angled connecting or fastening leg 21, with which the wire bow 13 with the pivoting device 1 is connectable. Alternatively, the wire hanger 13 or the foot leg 17 can also be fastened laterally to the threading hook 7. The type of attachment of the wire bracket 13 to the pivoting device 1 is neither described nor shown. It can be done by welding, gluing, clamping or other means of connection. The distance between the two longitudinal legs 15, 19 and the horizontal extension of the foot leg 17 is preferably greater than twice the diameter of the needle 7.

The operation of the device will be explained in more detail below. After lowering the carrying and pivoting device 1 in the threading position, in which the hook 7 is exactly aligned in front of the eye 5 of the needle 3 (see. FIGS. 1 and 2 ), the foot leg 17 is located near the eye 5 on the needle 3. During the subsequent passage of the hook 7 through the eye 5 of the needle 3, the wire hanger 13 or its foot leg 17 under the hook 7 from the front hook end 9 away to the rear and panned down. The foot leg 17 always remains springy on the needle 3 fitting. After catching the upper thread 23, which has been positioned by suitable, not shown in the figures means before the eye 5 of the needle 3 under the hook 7, the hook 7 returns by the pivotal movement of the support and pivoting device 1 with the thread 23 back in the starting position according to FIGS. 1 and 2 and forms after a further pivoting movement and simultaneous axial raising of the support and pivoting device 1, a thread loop 25, which leads from the eye 5 in the needle 3 obliquely upwards to the hook 7. The also when pivoting the support and pivoting device 1 away from the needle 3 wire bracket 13 supports the two legs of the thread loop 25 at a distance from the front end 9 of the hook 7, thus preventing the thread loop 25 from sliding out of the hook 7, without the thread 23 to pinch. The sliding out of the upper thread 23 from the hook 7 after looping is prevented by raising the wire bar 13 or its leg 17 with the two legs 23a, 23b of the thread loop 25 with respect to the hook 7 and thus the angle between the thread loop 25 and the hook 7 is substantially reduced. The thread loop 25 between the foot leg 17 and the hook throat 10 extends approximately horizontally.

As soon as the carrying and swiveling device 1 with the thread loop 25 hanging thereon is moved even further upwards against the rest position (cf. FIG. 6 ), so the thread loop 25 can pivot with increasing traction wire bow 13 down and back and the sufficiently long thread loop 25 can fall out of the hook 7.
If the tensile force is too low, the thread loop 25 remains hanging in the rest position in the hook 7. The thread loop 25 can now be pulled by two fingers from the hook 7 or it can be sewn directly without pulling the thread loop 25 by hand from the hook 7. If the thread end 23b before inserting the thread 23 into the hook 7 is very short or is cut very short, the thread loop 25 can be pulled out during the raising of the threader. Most of the time, the thread end 23b will hang in the hook 7 and it can still be sewn directly.

In the FIGS. 7a to 7d the process of threading is shown again schematically.
In Figure 7a the hook 7 is spaced from the eye 5. The moving on a trajectory foot leg 17 of the wire bracket 13 (the latter in the FIGS. 7a to 7d omitted for better clarity) is already slightly springy on the needle 3. When entering and penetrating the hook 7 through the eye 5, the foot leg 17 is retained by the needle 3, he remains essentially at the in Figure 7a position ( FIG. 7b ). The needle thread 23 is already in the hook throat 10. It may be inserted by hand or fed by other suitable means. In FIG. 7c the threading hook 7 has moved back through the eye 5 and pulled the thread 23 as a thread loop 25 through the eye 5. The leg 17 of the foot has been released from the needle 3 during retraction of the hook 7 and now supports the thread loop 25 from below. When booting the carrying and pivoting device 1 (in the FIGS. 7a to 7d not shown), the foot leg 17 also moves upwards and supports the thread loop 25 in such a way that, for the time being, it can not fall out of the hook throat 10. The latter takes place only at the end of the upward movement of the support and pivoting device 1, before it enters the rest position.

Claims (5)

1. A device for securing the needle thread loop (25) after threading the needle thread (23) into the eye (5) of the needle (3) of a sewing machine, having a wire bracket (13) fastened to the support and pivot device (1) for a threading hook (7), said wire bracket comprising a foot leg extending approximately transversely to the needle (3) which lies in a vertical position,
   characterized in that
   the wire bracket (13) is arranged with respect to the threading hook (7) such that its foot leg (17) is spaced apart from and below the threading hook (7), such that the needle thread loop (25) pulled through the eye (5) of the needle (3) is supported from below by the foot leg (17) between the eye (5) of the needle (3) and the threading hook (7) and thereby is prevented from sliding out of the groove (10) of the threading hook (7).
2. The device according to claim 1, characterized in that the foot leg (17) is arranged such as to be able to be pivoted on a trajectory at a distance from and around the front end (9) of the threading hook (7).
3. The device according to any one of claims 1 or 2, characterized in that the wire bracket (13) is fastened above or beside the threading hook (7).
4. The device according to claim 3, characterized in that the foot leg (17) of the wire bracket (13) is in front of the hook grove (10) of the threading hook (7) in the position of rest and after the formation of the needle thread loop (25).
5. The device according to any one of claims 1 to 4, characterized in that the foot leg (17) is held on one side or both sides by the wire bracket (13).

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