EP0270780B1 - Hook-eye needle for book-binding machines, embroidery machines and the like - Google Patents

Description

The invention relates to a hook eye needle for book binding machines, embroidery machines and the like., With a needle shaft, which is followed by a needle head via a neck part, which has a substantially conical needle tip and carries a tongue, which forms the hook eye together with the neck part the side facing the needle tip is delimited by a rounded throat.

Hook eye needles, such as those used for pulling a thread loop through a work piece, for example the sheets of a book to be stitched together, are described in two common embodiments, for example in DE-C 642 703, where at the same time the function of a hook eye needle working with them is also described Bookbinding machine is briefly explained. Basically, these hook eye needles are used in such a way that they are pierced through the previously prepunched or unpunched work items until their tongues are exposed on one side and can catch a thread, which is then pulled through the work items in the form of a loop. Especially with hard work, such as this is the case, for example, when stapling the paper sheets of a book, the thread is exposed to considerable stress when the thread is pulled through the work piece. Namely, high frictional forces occur between the thread and the paper in the known hook eye needles, which leads to a considerable tensile load in the tip region of the needle. The consequence of this is damage to the thread, which affects the stability of the stitching or, for example in the case of embroidery machines, leads to an unclean appearance of the finished work piece. The difficulties naturally become greater the higher the operating speed of the hook eye needles, so that even thread breaks can occur. Accordingly, the working speed is limited by the thread stress.

The object of the invention is therefore to remedy this and to create a hook eye needle which ensures extensive protection of the thread when the thread loop is pulled through the work item and thus also allows the processing of thread material of lower quality and the achievement of high working speeds.

To solve this problem, the hook eye needle mentioned at the outset is characterized in that the needle head, starting at least in the area of the hook eye, is formed with two thread spaces lying on both sides of the longitudinal plane of symmetry of the needle and is tapered laterally over the needle tip and the conical needle tip in the area of the hook eye one throat has an upright, substantially rectangular cross-sectional shape with rounded or chamfered edges to the longitudinal plane of symmetry that cuts its narrow sides centrally.

This configuration of the needle head of the needle eye needle ensures optimal thread protection when pulling the thread loop through the work piece. The two legs of the thread loop running on both sides of the throat are protected within the thread clearances, so that they are not pressed laterally against the material of the work material when the thread loop is pulled through and thus practically no frictional forces occur between the thread material and the work material. The thread clearances are matched to the thickness of the thread material, so deep that the two legs of the thread loop laterally withdraw from the outline of the neck part or shaft of the needle forming the hole when piercing through the work piece, with the result that they pass through when the hook eye needle is withdrawn the hole in the work piece that is more widened in this area can be pulled through without hindrance.

In practice it has proven to be particularly advantageous if the lateral taper of the needle head between the throat or the needle shaft and the end of the needle tip is at least a quarter of the needle shaft width or the needle shaft diameter on each side of the longitudinal symmetry plane. It has also proven to be advantageous if the needle head is tapered laterally concavely in the area of the throat of the hook eye. In order to give the needle tip greater stability, in particular when piercing hard work, it can be expedient be that the needle tip has a region extending from its end of substantially the same width. The end of the needle tip can then be designed as a cutting edge or cone tip lying in the longitudinal plane of symmetry of the needle.

The needle tip can be hollow ground laterally to form longitudinal thread guide grooves extending from the throat, whereby the guidance of the thread loop can be improved without unnecessarily further weakening the needle.

It can also be advantageous if the neck part is tapered laterally, beginning in the area before the end of the tongue, towards the needle tip on both sides of the longitudinal plane of symmetry of the needle, and the lateral tapering of the needle head is connected as a second taper to this first lateral taper. In this way, the required thread clearance is divided into two sections of the needle head and the needle neck one behind the other in the longitudinal direction of the needle, thus avoiding an abrupt taper in the needle head for various purposes. The tapered neck part can have a substantially same width at least in sections in the area lying in front of the second taper, which is advantageous with regard to the stability of the needle.

Finally, it is expedient if the tongue is slightly bent at the end towards the neck part to prevent the thread loop from sliding out of the hook eye and to prevent skipped stitches and hooking into the work piece. In addition, the adjustment to a predetermined hook eye opening is facilitated.

• Fig. 1 eine Hakenöhrnadel gemäß dem Stand der Technik, für eine Buchbinderheftmaschine, in einer Seitenansicht, im Ausschnitt,
• Fig. 2 und 3 die Hakenöhrnadel nach Fig. 1, geschnitten längs der Linie II-II bzw. III-III der Fig.1,
• Fig. 4 die Hakenöhrnadel nach Fig. 1, in einer Draufsicht, mit zugeordneter Fadenschlinge und im Ausschnitt,
• Fig. 5 eine Hakenöhrnadel gemäß der Erfindung, in einer Seitenansicht und in einer Darstellung entsprechend Fig. 1,
• Fig. 6 und 7 die Hakenöhrnadel nach Fig. 5, geschnitten längs der Linie VI-VI bzw. VII-VII der Fig. 5,
• Fig. 8 die Hakenöhrnadel nach Fig. 5, in einer Draufsicht und in einer Darstellung entsprechend Fig. 4,
• Fig. 9 die bekannte Hakenöhrnadel nach Fig. 1, geschnitten längs der Linie II-II, unter Veranschaulichung des Arbeitsgutes und der eingelegten Fadenschlinge beim Durchziehen durch das Arbeitsgut, in einem anderen Maßstab, und
• Fig.10 die erfindungsgemäße Hakenöhrnadel nach Fig.5, geschnitten längs der Linie VI-VI der Fig. 5 und in einer Darstellung entsprechend Fig. 9.

In the drawing, an embodiment of the object of the invention is shown in comparison to a conventional hook eye needle. Show it:

• 1 a hook eye needle according to the prior art, for a bookbinding machine, in a side view, in a detail,
• 2 and 3, the hook eye needle of FIG. 1, cut along the line II-II and III-III of Fig.1,
• 4 shows the hook eye needle according to FIG. 1, in a top view, with an associated thread loop and in the cutout,
• 5 shows a hook eye needle according to the invention, in a side view and in a representation corresponding to FIG. 1,
• 6 and 7, the hook eye needle according to FIG. 5, cut along the line VI-VI and VII-VII of FIG. 5,
• 8 shows the hook eye needle according to FIG. 5, in a top view and in a representation corresponding to FIG. 4,
• Fig. 9, the known hook eye needle of FIG. 1, cut along the line II-II, with illustration the work item and the inserted thread loop when pulling through the work item, on a different scale, and
• 10 shows the hook eye needle according to FIG. 5, cut along the line VI-VI of FIG. 5 and in a representation corresponding to FIG. 9.

The known hook eye needle shown in FIGS. 1 - 4 and 9 for a comparative clarification of the invention corresponds approximately to the embodiment according to the figures 7, 8 of DE-PS 642 703, as it is used in a similar way on a large scale in practical use. The hook eye needle has a needle shaft 1 of circular cross-sectional shape, which is formed with a clamping or screwing part (not shown in the drawing) and to which a needle head 3 is connected via a neck part 2 and which has an essentially conical needle tip 4, the point-shaped of which End, the actual "tip", labeled 5. The needle head 3 carries a molded tongue 6 which, together with the top of the neck part 2, forms the hook eye 7, which is delimited by a rounded throat 8 on the side facing the needle tip 4. The needle neck part 2 is arranged in a recessed manner with respect to the upper side of the needle shaft via a needle chest area 9, so that the upper edge of the tongue 6 is flush with the upper side of the needle shaft or is somewhat set back against it. The underside of the needle shaft is just continuously formed over the neck part 2 up to the needle tip 4.

The end of the needle tongue 6 at 10 is inclined somewhat inwards towards the neck part 2; the opening width of the hook eye 7, which is otherwise essentially parallel-flanked, is also dimensioned such that the thread associated with this needle size can slide freely through the hook eye 7. As can be seen from Fig. 4, the tongue 6 is at its end also somewhat tapered laterally, but embodiments are also in use in which the tongue 6 tapers only slightly at the end, as is indicated by dash-dotted lines at 11. In its remaining course, the tongue 6 has essentially the same width as the neck part 2.

5-9 and 10, in contrast, the hook eye needle according to the invention is shown in comparison, the same or corresponding parts being provided with the same reference numerals. To the extent that they correspond to those of the embodiment according to FIGS. 1-4, these features are not explained again.

The needle head 3, starting at 12 in the region of the hook eye 7, is tapered on both sides of the longitudinal plane of symmetry of the needle indicated at 13 in FIG. 8, so that two thread spaces, which are designated by 14, are formed on both sides of the longitudinal plane of symmetry 13 . The conical needle point 4 has in the region of the throat 8 of the hook eye the upright standing, essentially rectangular cross-sectional shape shown in the sectional view according to FIG. 6 with 15 rounded edges, the narrow sides 16 of which are cut centrally by the longitudinal plane of symmetry 13. The lateral taper of the needle head 3 between the throat 8 and the end 5 of the needle tip 4 is on each side of the longitudinal plane of symmetry 13 at least a fourth of the needle shaft width, ie the diameter of the cylindrical needle shaft 1, the cross-sectional image of which is indicated at 17. The Both of the lateral tapering of the needle head 3 mentioned have concave wall regions in the region of the throat 8 at 18, which then merge in the manner shown in FIG. 8 into a region 19 which extends from the end 5 of the needle tip 4 and has essentially the same width. The end 5 of the needle tip 4 is designed as a cutting edge or cone tip lying in the longitudinal plane of symmetry 13 of the needle (cf. FIG. 5).

The needle tip 4 is laterally hollow ground to form longitudinally running thread guide grooves 20 starting from the throat 8, as can be seen from FIG.

The neck part 2 is in contrast to the embodiment according to FIGS. 1-4, starting in the area in front of the end 10 of the tongue 6, to the needle tip 4 on both sides of the longitudinal plane of symmetry 13 tapered laterally at 21, such that the so The first lateral taper formed connects the lateral taper already explained at 14 of the needle head 3 as a second taper. The tapered neck portion has an essentially identical width in the region lying at 14 in front of the second taper (at least in sections) (FIG. 8).

Finally, the tongue 6 is slightly bent at the end at 22 with a section towards the neck part 2 in order to ensure that the thread is securely held in the hook eye 7.

In operation, the above is compared to the state of the art described hook eye needle mt her needle tip 4 through the work item schematically indicated at 22, for example. The superimposed sheets of a book, penetrated so far that the cylindrical needle shaft 1 passes through the work item 22 (see. Fig. 4.8). This creates a cylindrical hole in the work piece 22, the shape of which is given by the cross-sectional shape 17 of the needle shaft.

A thread 23 is inserted into the hook eye 7 of the needle head 3 projecting over the work item 22, which thread is pulled out into an essentially U-shaped thread loop when the hook eye needle moves back, which thread is pulled through the work item 22. As can be seen from FIGS. 9 and 10, the stresses on the thread 23 in the known hook eye needle shown in FIGS. 1 to 4 are fundamentally different from those for the hook eye needle according to the invention illustrated in FIGS. 5 to 8:

In the known hook eye needle, the thread 23 of the U-shaped thread loop is laterally squeezed at 24 between the edge of the pre-punched hole in the work piece 22 and the needle head 3 in the region of the throat 8, whereby it is partially forced to create the needle shaft 1 To expand the opening in the work item 22 locally. The result of this is that the thread 23 is exposed to a high frictional stress when it is pulled through the work material 22, which leads to an excessive tensile stress on the thread loop in the region of the throat 8 and can damage or even break the thread.

In contrast to this, with the hook eye needle according to the invention (FIG. 10) the two legs of the thread loop when pulling through the pre-pierced opening of the work material 22 in the thread spaces 14 are in any case within the outline of the cylindrical needle shaft 1 shown in dash-dotted lines in FIG The result of this is that the thread of the thread loop is not frictionally inhibited by the work good 22 when it is pulled through the work good 22, but is essentially pulled freely and unhindered through the pre-punched hole. The tensile force exerted on the thread 23 in the area of the thread loop is essentially given exclusively by the thread tension specified by the thread delivery device and possibly a low resilient inherent elasticity of the hole edge in the work piece 22. As can be seen, the needle head 3, with its rectangular cross-sectional shape, is designed essentially in the manner of a flat web, which leaves the thread 23 with sufficient lateral freedom of movement in the thread spaces 14 lying on both sides.

The lateral taper at 21 of the neck part 2 (Fig. 8) can alternatively be omitted. The width of the hook eye 7 corresponds approximately to the thickness of the thread 23 assigned to the respective needle size, wherein it is selected to be slightly larger in order to ensure a free thread flow.

The new hook eye needle shown is rotated by 90 ° about its axis after the thread loop has been pulled through the work piece, in order to enable the gripper to freely pass through the thread loop, as is generally necessary. Therefore, the thread guide grooves 20 are also aligned approximately axially parallel. However, embodiments are also conceivable in which the needle head 3 and the thread guide grooves 20 are twisted spirally in order to make it unnecessary in the manner explained in DE-PS 642 703 to turn the hook eye needle after it has been pulled through the work piece 22.

All edges and transitions in the thread guide area, ie in the area of the hook eye 7, the throat 8 and the needle tip 4 are perfectly rounded, which also applies to the tongue 6. The throat surface and all transitions in the area of the throat 8 are also highly polished and free of machining features, which has an advantageous effect on the thread flow and the needle stability. The two guide grooves 20 result in a perfect entry into the throat 8, while at the same time ensuring a sufficiently large free space without unnecessarily weakening the needle.

The needle head 3, which is essentially rectangular in cross section, is rounded off at 15, as can be seen from FIG. 6. Alternatively, chamfers on the edges could also be provided.

The height of the needle head 3 (and the tongue 6) measured in the longitudinal symmetry plane 13 can, as can be seen from FIG. 10, be somewhat smaller than the diameter of the cylindrical needle shaft 1, i.e. be somewhat smaller than the maximum needle shaft height, with the result that the needle head 3 also passes through the work item 22 essentially unimpeded through the hole punched by the needle shaft 1.

Claims (10)

1. A bearded needle for bookbinding machines, embroidery machines and the like, having a needle shank (1) adjoined via a neck portion (2) by a needle head (3) having a substantially conical needle tip (4) and bearing a beard (6) which cooperates with the neck portion (2) to form a needle eye (7) which is bounded by a rounded fillet (8) on the side adjacent the needle tip (4), characterized in that the needle head (3), starting at least in the zone of the needle eye (7), is constructed tapering steplessly laterally in the direction of the needle tip (4), to form two thread travelling areas (14) disposed on both sides of the longitudinal plane of symmetry (13) of the needle, and in the zone of the fillet (8) of the needle eye (7) the conical needle tip (4) has an upright, substantially rectangular cross-sectional shape which has rounded or chamfered edges (15) and is symmetrical in relation to the longitudinal plane of symmetry (13) intersecting the centre of its narrow sides (16).
2. A bearded needle according to claim 1, characterized in that the lateral taper (at place 14) of the needle head (3) between the fillet (8) or the needle shank (1) and the end (5) of the needle tip (4) amounts to at least one quarter of the needle shank width or diameter on each side of the longitudinal plane of symmetry (13).
3. A bearded needle according to claims 1 or 2, characterized in that the needle head (3) tapers laterally concavely (at place 18) in the zone of the fillet (8) of the needle eye (7).
4. A bearded needle according to one of the preceding claims,
   characterized in that the needle tip (4) has a zone (19) of substantially equal width extending from its end (5).
5. A bearded needle according to claim 4, characterized in that the end (5) of the needle tip (4) takes the form of a cutting edge or a conical tip disposed in the longitudinal plane of symmetry (13) of the needle.
6. A bearded needle according to one of the preceding claims, characterized in that the needle tip (4) is hollow ground on its sides to form longitudinally extending thread guide grooves (20) starting at the fillet (8).
7. A bearded needle according to one of the preceding claims,
   characterized in that the neck portion (2), starting in the zone (21) before the end (10) of the beard (6), tapers laterally in the direction of the needle tip (4) on both sides of the longitudinal plane of symmetry (13), and said first lateral taper is adjoined as a second taper by the lateral taper (at place 14) of the needle head (3).
8. A bearded needle according to claim 7, characterized in that the tapered neck portion (2) has substantially the same width at least in portions in the zone disposed before the second taper (at place 14).
9. A bearded needle according to one of the preceding claims,
   characterized in that the end of the beard (6) is slightly bent towards the neck portion (2).
10. A bearded needle according to one of the preceding claims,
    characterized in that the height of the needle head (3), measured in the longitudinal plane of symmetry (13), is smaller than the maximum height of the needle shank.

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