EP0291687B1 - Latch needle for stitch-forming textile machines - Google Patents

Description

The invention relates to a latch needle for stitch-forming textile machines, with a steel needle shaft, which has a molded-on needle hook and a tongue slot, and with a needle tongue made of a non-metallic material, which is pivotally mounted in the tongue slot about a transverse tongue axis and in its closed position rests with her spoon on the needle hook and in her fully open position with the tongue back on contact surfaces in the area of the upper edge of the needle shaft.

In the case of fast-running stitch-forming textile machines, for example circular knitting machines, the needle tongues of the latch needles are exposed to very high loads. When the needle tongue is pivoted between its closed and its fully open position (reserve) at a frequency of 60 Hz and more, as is customary today, high acceleration and deceleration forces occur on the needle tongue. This not only stresses the needle tongue on bending, but it is considerable when the spoon strikes the hook or the needle tongue back on the contact surfaces provided on the needle shaft To absorb energy through bending elastic deformation and to destroy it through friction. As a result of these high stresses, not only can the spoon and the hook be damaged, but also tongue breaks or damage to the tongue bearing and the needle shaft can occur.

Various measures have already been taken to avoid such damage. So it is e.g. from DE-PS 27 14 607 known to elastically intercept the impact of the needle tongue in the reserve by a special design of the needle tongue slot. This very effective measure, however, cannot influence or mitigate the undamped impact of the spoon of the needle tongue on the needle hook.

In addition, a tongue needle is known from DE-PS 33 31 031, in which the needle tongue has at least one continuous recess in the area between its bearing bore and the spoon. The resulting reduction in mass reduces the acceleration and deceleration forces that occur during the pivoting movement of the needle tongue and the impact energy released when the spoon strikes the hook or the back of the tongue on the associated contact surfaces of the needle shaft. However, the introduction of such recesses into a needle tongue is associated with considerable effort in the case of fine needles because of the tiny dimensions of the needle tongue.

Finally, DE-PS 1046 819 discloses a latch needle for knitting machines, in particular for hand knitting apparatuses, the tongue of which consists of one non-magnetizable material, for example beryllium bronze or synthetic molding material. By using a non-magnetizable material for part of the needle head and in particular for the needle tongue, sticking of the needle tongue to the hook due to remanent magnetism is to be avoided, as occurs occasionally in a manual needle made of a uniformly made of magnetizable steel latch needle. There is no such problem with latch needles that work in industrial knitting machines. In addition, needle tongues made of beryllium bronze or pressed material cannot withstand the stresses to which they are exposed in high-speed circular knitting machines in the long run.

The object of the invention is to provide a latch needle which is particularly suitable for high-speed machines, the latch of which is able to absorb the stresses occurring in particular when the spoon hits the hook and its back on the contact surfaces on the needle shaft, without damage damage to the hook or the needle shaft itself are avoided at the same time.

To achieve this object, the latch needle mentioned at the outset is characterized according to the invention in that the latch tongue consists of a fiber-reinforced thermoplastic homo- or copolymer plastic.

Examples of suitable plastics are Polyurethanes and polyamides, to name just two. Compared to steel, non-metals or pressed materials, these plastics have a significantly improved internal damping; as has been established, they have an elasticity behavior which is outstandingly suitable for the new intended use. The flexural strength increases the flexural strength to such an extent that the needle tongue can withstand the mechanical loads that occur even over long periods of operation. Compared to the known steel needle tongues, this results in a weight saving of approx. 65% with a correspondingly reduced mass inertia and thus reduced impact energy which is released when striking the hook or the contact surfaces on the needle shaft. The needle tongue can be produced by precision micro-injection molding, a balanced mass distribution within the needle tongue being possible without further ado.

In order to facilitate the assembly of the needle tongue, the arrangement can advantageously be made such that the needle tongue has an insertion slot for the tongue axis that opens laterally into its bearing bore and is delimited by elastically deformable needle tongue regions. This makes it possible to insert the tongue axis before installing the tongue to arrange the needle shaft and then pivotally attach the needle tongue by simply clipping it onto the tongue axis.

The insertion slot can expediently be formed starting from an edge-side depression which further facilitates assembly. If there is a risk, in particular in the case of larger needle tongues, that when the tongue is slipped onto the tongue axis, the elastic expansion limit of the elastically evading needle tongue regions is exceeded, the needle tongue can also have at least one relief slot extending from the bearing bore and enlarging the elastically deformable needle tongue regions. This relief slot can advantageously end at the end in a recess in the needle tongue shaft in order to rule out the occurrence of an undesirable notch effect at this point. It has proven to be useful if the recess is a bore.

At least the insertion slot can advantageously be arranged on the side opposite the spoon, for example lying in the middle of the needle tongue, but other arrangements of the insertion slot, for example from the back of the tongue or from the opposite side of the needle tongue, are also conceivable.

Since, as mentioned, the needle tongue is produced in a precision micro-injection molding process, not only can a bearing bore of perfect quality be guaranteed, but it is also straightforward possible to form parts on the needle tongue itself, the production of which would be difficult in a mechanical production process, such as stamping, etc. For example, it is possible for the needle tongue to be coupled in a rotationally fixed manner to the tongue axis, which is rotatably mounted in the needle shaft, via molded, non-cylindrical regions of its bearing bore.

• Fig. 1 eine Zungennadel gemäß der Erfindung, in einer Seitenansicht, teilweise aufgeschnitten und in einer Teildarstellung,
• Fig. 2 die Zungennadel nach Fig. 1, in einer abgewandelten Ausführungsform und in einer entsprechenden Darstellung,
• Fig. 3 die Nadelzunge einer Zungennadel gemäß der Erfindung,in einer weiteren abgewandelten Ausführungsform, in einer Untersicht, teilweise im Schnitt, und
• Fig. 4 die Nadelzunge nach Fig. 3, in einer Seitenansicht, mit aufgeschnittenem Löffel.

Exemplary embodiments of the subject matter of the invention are shown in the drawing. Show it:

• 1 is a tongue needle according to the invention, in a side view, partially cut open and in a partial view,
• 2, the latch needle according to FIG. 1, in a modified embodiment and in a corresponding representation,
• Fig. 3 shows the needle tongue of a latch needle according to the invention, in a further modified embodiment, in a bottom view, partially in section, and
• Fig. 4, the needle tongue of Fig. 3, in a side view, with a cut spoon.

1, 2 has a needle shaft 1 which carries a molded-on needle hook 2 at the end and in which a tongue slot 3 which is symmetrical to the longitudinal center plane of the needle shaft 1 is formed in a known manner. A transverse cylindrical tongue axis 4 is mounted in the cheeks of the needle shaft 1 which delimit the tongue slot 3 on both sides. The tongue axis 4 can be formed in one piece or in two parts. It can be inserted into corresponding bores of the cheeks delimiting the tongue slot 3 or pressed out of these.

On the tongue axis 4, a tongue 5 is pivotally mounted in the tongue slot 3, which in the closed position shown in FIGS. 1, 2 rests with its spoon 6 on the needle hook 2, while it is in its fully open position (reserve ) with the back of her tongue resting on contact surfaces in the area of the upper edge of the needle shaft 1. The needle tongue 5 consists of a fiber-reinforced homopolymer or copolymer, for example polyurethane or polyamide. The fiber reinforcement can consist of organic or inorganic fibers, including glass fibers and carbon fibers. The fibers can be mixed into the plastic, but it is also possible to provide an oriented fiber arrangement, for example oriented in the longitudinal direction of the needle tongue. The needle tongue 5 is by precision micro injection molding produced.

At its end opposite the spoon 6, designed as a bearing eye, the needle tongue 5 is formed with a transverse bearing bore 7, which is cylindrical in the embodiments according to FIGS. 1 and 2 and by means of which the needle tongue 5 can be pivoted with tight play on the cylindrical tongue axis 4 is stored. An insertion slot 8 for the tongue axis 4 opens laterally into the bearing bore 7 and is delimited on both sides by elastically deformable needle tongue regions 9. The insertion slot 8 starts from an edge-side depression 10 which facilitates assembly and is arranged on the side opposite the spoon 6, approximately lying in the tongue center plane.

In the embodiment according to FIG. 2, a relief slot 11 adjoins the insertion slot 8 on the opposite side of the bearing bore 7 in the continuation of the insertion slot 8, which enlarges the elastically deformable needle tongue regions 9 encompassing the bearing bore 7 and ends in a cylindrical manner Bore 12 formed through recess of the tongue shaft 13 opens.

When manufacturing the described tongue needle, the tongue axis 4 is first inserted into the needle shaft 1. Subsequently, the recess 5 of the needle tongue 5 is placed on the tongue axis 4 and clipped onto the tongue axis 4 by a slight pressure in the direction of the insertion slot 8. The tongue areas 9 lying on both sides of the insertion slot 8 become elastic to the side; as well as the tongue axis 4 in the bearing bore 7, they snap together, so that the needle tongue is pivoted properly.

The embodiment according to FIG. 1, in which the elastically deformable regions 9 only extend as far as the bearing bore 7, is particularly intended for smaller needle types, in which the diameter of the tongue axis 4 is also correspondingly small.

In the embodiment according to FIG. 2, which is intended in particular for needle designs with larger dimensions, the relief slot 11 extends the elastically deformable needle tongue regions 9, so that even with a larger diameter of the tongue axis 4 there is no plastic deformation of the tongue regions 9 during assembly of the needle tongue 5 is to be feared.

3, 4, the needle tongue 5 is shown in a slightly modified form in its details. Deviating from the embodiment according to FIGS. 1, 2, the bearing bore 7 is not assigned an insertion slot 8, so that this needle tongue is mounted in the conventional manner in such a way that its end toward the bearing eye is first inserted into the tongue slot 3, whereupon the tongue axis 4 is used.

The bearing bore 7 itself can, as in FIGS. 1, 2, be cylindrical, the tongue axis 4 then is rotatably fixed in the cheek of the needle shaft 1 delimiting the tongue slot 3. Alternatively, however, it is also conceivable, in the manner shown in FIG. 4, to form a non-cylindrical region on the needle tongue 5 in the region of the bearing bore 7, for example in the form of a surface 15, via which the needle tongue 5 rotates with the correspondingly profiled tongue axis 4 is coupled, which in turn is then rotatably mounted in corresponding holes in the cheeks of the needle shaft 1.

Claims (8)

1. A latch needle for knitting machines, having a steel needle shank having a shaped-on needle hook and a latch slot, and a needle latch made from a non-metallic material which is mounted in the latch slot to pivot around a transversely extending latch rivet and which in its closed position bears via its noucat against the needle hook and in its completely opened position bears via the latch back against bearing surfaces in the zone of the needle shank top edge, characterized in that the needle latch (5) is made from a fibre-reinforced thermoplastic homopolymeric or copolymeric plastics.

2. A latch needle according to claim 1, characterized in that the needle latch (5) has for the latch rivet (4) an introduction slot (8) which opens from outside laterally into its latch bearing bore (7) and is bounded by resiliently deformable needle latch zones (9).

3. A latch needle according to claim 1, characterized in that the introduction slot (8) is formed starting from an edge side depression (10) facilitating assembly.

4. A latch needle according to claims 2 or 3, characterized in that the needle latch (5) has at least one relieving slot (11) which starts from the bearing bore (7) and enlarges the resiliently deformable needle latch zones (9).

5. A latch needle according to claim 4, characterized in that the relieving slot (11) opens on its end side into a recess (12) in the latch shank (13).

6. A latch needle according to claim 5, characterized in that the recess is a bore (12).

7. A latch needle according to one of claims 2 to 6, characterized in that at least the introduction slot (8) is disposed substantially in the median plane of the latch on the side opposite the noucat (6).

8. A latch needle according to one of the preceding claims; characterized in that the needle latch (5) is rotatably connected via shaped-on non-cylindrical zones (15) of its bearing bore (7) to the latch axle (4) rotatably mounted in the needle shank (1).

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