EP2159311B1 - Hook needle with an oblique elliptic cross-section of the hook - Google Patents

Description

The invention relates to a knitting machine needle for knitting and knitting machines and in particular a hook needle for circular knitting machines.

document EP-A-1 449 947 discloses a knitting machine needle according to the preamble of claim 1.

Hook needles for circular knitting machines are basically known. They have an elongated shaft, which is provided at one end with a hook. The hook serves to pick up a thread and pull it through a stitch already formed on the shaft to form a stitch. To enclose the picked thread in the hook, other means may be provided, such as tongues pivotally mounted on the shaft, slides or the like.

When knitting in a course of stitches takes place serially, a so-called robbing-back effect can be observed in the stitch forming operation. The knitting knitting needle pulls the picked thread through the older on the Shank-fitting stitch, tightening thread. It forms a half stitch whose two stitch loops are on both sides of the hook. The one stitch loop goes over into the supplied thread, while the other loop loop merges into the adjacent, shortly before formed half stitch. In this knitting process, a tendency can be observed that when the new semi-stitch is formed, thread is drawn over from the half stitch already formed just before, resulting in a reduction in size of the older half stitch. This effect is called a "robbing-back effect" and can be undesirable.

On this basis, it is an object of the invention to provide a knitting machine needle with which the robbing-back effect can be influenced.

This object is achieved by the characterizing features of claim 1. The hook has at least one point on an oval cross-section, which is oriented obliquely to a needle transverse direction. The possibility of achieving the mentioned asymmetry of the hook cross section is given by the inclination of the symmetrical cross section with respect to the longitudinal center plane containing the hook tip.

The asymmetry causes the curvature of the thread taken from the hook when a half stitch is formed to be different on both sides of the hook. At the beginning of the stitch formation, the oval and inclined hook cross-section initially leads to a smaller wrap and thus to a lower frictional force between the hook and the thread. Therefore, the stitch formation process starts off very gently and gently. The thread can be easily pulled from the hook. When the long axis of the oval cross section of the thread is oriented approximately parallel to the thread to be fed, ie, when the angle included between the long axis of the oval cross section and the transverse direction of movement of the needle opens towards the incoming thread, the stitching process is promoted and the robbing Reduced back-effect.

However, the asymmetry of the hook cross-section can also, if desired, be used to reinforce the robbing-back effect, for example if very dense knitted fabrics are to be produced in a targeted manner.

The needle according to the invention is preferably used in knitting machines with asymmetrically constructed knitting locks, as they are usually found in circular knitting machines. Such a circular knitting machine with asymmetric locks is designed only for operation in one direction of rotation. The needles held by the needle cylinder or the dial are always moving in a predetermined needle transverse direction through the control cam of the needle locks. The stitch formation always takes place in the same direction. The thread is always fed to the needles from the same side. If, for example, the knitting cylinder rotates counterclockwise when viewed from above, the oval cross-sections seen in vertical section are turned clockwise with their large axes out of the horizontal, ie their large axes drop off to the right.

The oblique arrangement according to the invention of the oblong oval hook cross-section leads to a desired distribution of the loop friction between the thread and the hook surface along the thread. The further the knitting needles are withdrawn into their needle channel, the larger the wrap becomes, and thus the wrap friction also increases. In this case, the oblique arrangement of the oval hook cross-section causes that end of the thread, which is held by the fabric already formed, subject to a larger wrap than the free end of the thread which is connected to the thread supply. To achieve this, the long axis of the oval cross section is arranged ascending from the previously formed knit. Because of the lower wrap friction to the yarn supply and the larger wrap friction to the already formed fabric towards the needle pulls preferably pre-submitted thread in the loop to be formed and pulls the thread of the older adjacent mesh less. The robbing-back effect is reduced.

As mentioned, by opposing oblique arrangement of the oval cross-section also an increase in the Robbing-back effect can be achieved, if desired.

The oval cross section can be characterized by two axes, one of which characterizes the largest diameter of the cross section and the other the smallest diameter of the cross section. The largest axis marking the first axis is oriented obliquely to the needle transverse direction. The needle transverse direction is perpendicular to the flanks of the knitting machine needle and thus perpendicular to the needle longitudinal direction. The needle longitudinal direction corresponds to the longitudinal direction of the shaft of the knitting machine needle. The shaft is straight, ie the hook is neither bent laterally bent or bent out of the needle longitudinal direction laterally in any other way. In other words, there is a longitudinal median plane on which lies a center line extending from the needle point through the hook and the shaft.

The acute angle α, which includes the first axis with the needle transverse direction, is preferably in the range between 20 ° and 40 ° and is preferably 30 °. Thus, the first axis for most applications of the knitting machine needle is oriented substantially parallel to the incoming thread, whereby the desired friction conditions are produced. The acute angle α can vary along the hook or be constant. The constancy of the acute angle α along the hook cross section is sufficient for many applications to bring about the desired effect. However, it may also be expedient to set the acute angle in areas near the tip of the hook, which can be seen as a hook head, to a different value than at pointed distant areas, which are closer to the needle breast rise. For example, it may be appropriate to set the acute angle α at the needle head to about 30 °, while it is smaller or possibly larger in other areas.

Preferably, the cross-sectional area of the asymmetrical hook cross-section decreases toward the hook tip. If appropriate, the cross-sectional area can also be designed to coincide with one another at several points of the hook.

The asymmetrical cross section may be formed as an elliptical cross section. This is asymmetrical, as explained above, because of the inclination of the first axis (major axis) of the ellipse to the transverse direction of the needle with respect to the centerline. However, the ellipse cross-section in itself represents a symmetrical shape. The ellipse shape is symmetrical with respect to both the first axis and the second axis. In addition, it is point-symmetrical with respect to its center.

However, the oval cross-section may also have a lesser degree of symmetry in itself. For example, it may be asymmetrical in itself, for example by being ovate.

• Figur 1 eine Rundstrickmaschine, in schematisierter ausschnittsweiser Perspektivdarstellung zur Veranschaulichung eines Strickvorgangs,
• Figur 2 eine Maschinenstricknadel der Strickmaschine nach Figur 1, in ausschnittsweiser Perspektivansicht,
• Figur 3 die Maschinenstricknadel nach Figur 2, in Seitenansicht,
• Figur 4 die Maschinenstricknadel nach Figur 3, geschnitten entlang der Linie IV-IV in Figur 3,
• Figur 5 zwei Nadeln während eines Strickvorgangs, wobei ihre Haken entlang der Linie IV-IV in Figur 3, geschnitten sind,
• Figur 6 eine schematische Darstellung der Umschlingungsverhältnisse einer Strickmaschinennadel mit elliptischem Hakenquerschnitt in verschiedenen Stadien des Strickvorgangs, und
• Figur 7 die Umschlingungsverhältnisse an einer Strickmaschinennadel mit eiförmigen Hakenquerschnitt in verschiedenen Stadien des Strickvorgangs.

Further advantageous details of the invention or other circumstances are the subject of subclaims, the description or the drawing. The drawing and the description are limited to the presentation of essential elements of the invention and other conditions. The drawing complements the description of the embodiments. Show it:

• FIG. 1 a circular knitting machine, in schematic fragmentary perspective view for illustrating a knitting process,
• FIG. 2 a machine knitting needle of the knitting machine FIG. 1 in a fragmentary perspective view,
• FIG. 3 the machine knitting needle after FIG. 2 , in side view,
• FIG. 4 the machine knitting needle after FIG. 3 , cut along the line IV-IV in FIG. 3 .
• FIG. 5 two needles during a knitting operation, with their hooks along the line IV-IV in FIG. 3 , are cut,
• FIG. 6 a schematic representation of the Umschlingungsverhältnisse a knitting machine needle with elliptical hook cross section in various stages of the knitting process, and
• FIG. 7 the Umschlingungsverhältnisse on a knitting machine needle with egg-shaped hook cross section in various stages of the knitting process.

In FIG. 1 a circular knitting machine 1 is partially illustrated, in the knitting cylinder 2 knitting machine needles 3 according to the invention are arranged. To distinguish, the knitting machine needles carry 3 letter indices a, b, c, d, e. However, the knitting machine needles 3a to 3e are formed the same among each other, so that reference will be made below to the description of a single knitting machine needle 3a to 3e with reference numeral 3 to the needle.

The needle cylinder 2 of the circular knitting machine 1 has needle channels 4a to 4e, which are arranged vertically on the lateral surface of the knitting cylinder and in which the knitting machine needle 3 are displaceable in their respective needle longitudinal direction. The needle longitudinal direction is correct FIG. 1 coincide with the vertical direction. To move each knitting machine needle 3 is a knitting lock 5 with at least one control cam 6, at the cam surface 7 feet 8 (8a-8e) of the knitting needles 3 slide along, whereby the longitudinal movement of the knitting machine needle 3 is formed. While the knitting cam 5 rests, the knitting cylinder 2 rotates in the direction of the arrow 9, ie in the embodiment FIG. 1 counterclockwise. The running direction of the knitting cylinder 2 is fixed and remains unchanged during operation. Using this fact, the control cam 6 is optimized for the movement of the knitting machine needles 3 and thus formed asymmetrically (ie, its rising edge is different from its descending edge). The knitting needles wear a knitted fabric 10 for the manufacture of the knitting machine continuously a yarn 11 is supplied. The thread feeding takes place at a stationary location, while the knitting cylinder 2 and with it the knitting machine needle 3 rotate.

FIG. 2 As can be seen, the knitting machine needle 3 has a straight shaft 12 which extends parallel to an indicated by an arrow longitudinal direction L and on which at least one foot 8 is formed (not shown). The shaft 12 is bounded by two substantially planar flanks 13, 14, which are arranged substantially parallel to each other. At the bottom of each needle channel 4, the knitting machine needle 3 rests with its needle back 15, while its needle top 16 faces radially outward.

At the end a hook 17 is formed on the shaft 12, which ends in a tip 18. The hook 17 is associated with a tongue 19 which is pivotally mounted in a tongue slot 20 and serves to open the hook 17 or close. The tongue can for this purpose rest with one end 21 at the end of the hook or pivot away from the hook 17.

How out FIG. 3 As can be seen, a longitudinally extending through the shaft 12 center line 22 can be thought, which extends as a curved line through the hook and the tip 18 intersects. The center line 22 is preferably in a plane that in FIG. 3 is parallel to the drawing plane. This plane forms a median plane M which is in FIG. 4 is indicated as a dotted line. The median plane extends centrally through the knitting machine needle 3 and its tongue 19.

A special feature of the knitting machine needle 3 according to the invention lies in the formation of the hook 17. This preferably has at at least one point, for example at its head 17a, an oval obliquely oriented to the needle transverse direction Q cross-section 23, as he from FIG. 4 is apparent. The head 17a is the portion of the hook 17 between the hook tip 18 and the needle back 15, in particular its U-shaped arc.

For further explanation, first on FIG. 3 directed. Towards the hook 17, the needle top 16 descends in a breast rising region 24 towards the beginning 25 of the hook 17. The needle cross-section may be formed in the breast rising region 24 round or as a rectangular cross-section with rounded corners. He is there symmetrical to the median plane M. In the hook 17, however, the cross section may be formed asymmetrically at least at one point with respect to the center of life M. In FIG. 3 For clarity, different cutting lines S1, S2, S3, S4, S5, S6 are indicated. For example, in the section line S1, a round, substantially circular cross section may be given, which at S2 in a part further away from the breast rising region 24 of the hook 17 merges into an oval cross section. The oval cross-section may also be present at the cutting lines S3, S4, S5 and, for example, at S6, ie in approach to the needle tip 18 back over in a round cross-section.

FIG. 4 shows the hook, cut at the cutting line S4, with the arrow indicated by FIG. 3 indicated viewing direction. As can be seen, the oval cross section is designed here as an ellipse cross section. The centroid F of this ellipse lies on the median plane M. The centroid F is the center of the elliptical cross section 23. The direction of the largest diameter D1 of the cross section (eg the ellipse) defines a first axis A1. The direction of the smallest diameter D2 defines a second or minor axis. Both axes A1, A2 pass through the centroid F.

As can be seen, the first axis A1 is inclined at an angle α to the needle transverse direction Q, which is perpendicular to the longitudinal center plane M. The acute angle α is preferably 30 °. It may vary, but is preferably at least in the range of 20 ° to 40 °. The first axis A1 is preferably oriented substantially parallel to the yarn 11, when the knitting machine needle 3 in the extended position according to the positions of the needles 3c, 3d in FIG. 1 stands.

These conditions apply to the hook 17 on the hook head 17a, ie at the location of the cutting line S4, which runs substantially parallel to the needle back 15 and thus approximately parallel to the longitudinal direction L. The embodiments also preferably apply correspondingly to the cross section of the hook 17 at the locations of the cutting lines S2, S3, S5 in the vicinity of the section line S4. Thus, the hook on the incoming thread 11 side facing a further opening edge R1 (in FIG. 4 . 6, 7 on the left) as on its opposite side (edge R2 in FIG. 4 . 6, 7 right). The edge R1 and R2 respectively follow the curvature of the hook 17 and the center line 22. The center line passes through the centroids F of all cross sections. The radius of curvature of the rim R1 is preferably greater than the radius of curvature of the rim R2. The radius of curvature of the centerline 22 is preferably between the radii of curvature from R1 and R2. The tangents to the edges R1, R2 are parallel to the median plane M.

The knitting machine needle 3 described so far operates as follows:

When the knitting cylinder 2 is rotating, the knitting machine needles 3 are carried in a circle with the knitting cylinder 2. Her feet 8 run along the cam track 7 of the control cam 6, whereby the knitting machine needles 3 are driven in turn at the stationary yarn feeding point. In FIG. 1 The knitting machine needles 3a, 3b, 3c move outward in drive directions, and the knitting machine needle 3c has just reached its reversal point. Its hook 17 stands above the thread 11 and captures it when, as already preceded, the needles 3e and 3d move downwards. The taken in the hook 17 thread 11 is thereby pulled by an older previously held on the shaft of the knitting machine needle 3e mesh 26.

The process is in FIG. 5 shown separately again. It can be seen on the knitting machine needle 3e that the half-stitch 27 just formed has two legs 28, 29 which, because of the different widths R1, R2 of the hook 17, encounter different friction conditions. This will also be out FIG. 6 clearly, which increases the circumstances and possibly represents something idealized. In the cross-section 23 illustrated there, a point 30 is marked, in which the tangent T applied to the inner surface of the hook is parallel to the transverse direction Q. Starting from this point, the way to the handle 28 extends with less curvature than the handle 29. The friction conditions, the Henkel 29 finds on the hook 17, thus differ from the friction conditions, the Henkel 28 finds. While the thread 11 in FIG. 1 Of the knitting machine needle 3d can be pulled very easily through the old mesh 26, it is hardly withdrawn thread from the previously produced half-stitch 27. Thus, the half-stitches of the knitted fabric once produced are not reduced in an unfavorable manner.

The effect can also be produced with oval cross-sections or other asymmetrical cross-sections that deviate from the elliptical shape. Such an embodiment is in FIG. 7 illustrated. The there existing non-circular cross-section 31 of the hook 17 has a centroid or centroid F '. Passing through this, in turn, the largest diameter D1 and the smallest diameter D2 can be determined, which then form again the first axis A1 and the second axis A2. Again, the major axis A1 is inclined to the transverse direction Q at an acute angle of preferably 30 °. Again, the tapering thread 11 facing edge R1 is wider than the edge R2 on the thread-running side. The edges R1 and R2 are along the hook 17 respectively those points where the hook surface is parallel to the longitudinal center plane M.

According to the invention, a knitting machine needle is proposed which has at least one point S2, S3, S4 or S5 of its hook with respect to a longitudinal center plane M asymmetrical cross-section. This cross section is an oval cross section, preferably an elliptical cross section. With this measure, the robbing-back effect can be specifically influenced during knitting.

reference numeral

1

knitting machine

2

knitting cylinder

3

Knitting machine needles (3a ... 3e)

4

Needle channels (4a ... 4e)

5

knitting lock

6

control cam

7

cam surface

8th

Foot (8a ... 8e)

9

arrow

10

knitted

11

thread

12

shaft

L

longitudinal direction

13, 14

flanks

15

needle back

16

needle breast

17

hook

17a

head

18

top

19

tongue

20

latch slot

21

The End

22

center line

M

midplane

Q

Needle transverse direction

23

cross-section

24

Chest rising range

25

Beginning of the hook 17

S1-S6

cut lines

F, F '

Centroid

D1

largest diameter

A1

first axis

D2

smallest diameter

A2

second axis

α

acute angle between the needle transverse direction and the first axis

26

old mesh

27

half stitch

28, 29

leg

30

Position at which tangent T is parallel to the transverse direction Q

31

cross-section

F '

Centroid / centroid

T

tangent

R1, R2

edge

Claims (13)

1. Knitting machine needle (3)
   with an elongated butt (12), which defines a longitudinal (L) direction of the needle and a transverse direction (Q) of the needle and on which a hook (17) is configured, wherein the longitudinal direction (L) of the needle corresponds to the longitudinal direction of the butt (12) of the knitting machine needle (3), and the transverse direction (Q) of the needle is a direction standing perpendicular to the flanks of the knitting machine needle (3) and thus to the longitudinal direction (L) of the needle, wherein a centre line (22) running from the point (18) of the knitting machine needle (3) through the hook (17) and the butt (12) lies in a longitudinal centre plane (M), wherein in at least one location (S4) the hook (17) has an asymmetrical cross-section (23) with respect to this longitudinal centre plane (M),
   characterised in that the cross-section is an oval cross-section (23) and that the cross-section (23) has a largest diameter (D1) in a first axis (A1) and a smallest diameter (D2) in a second axis (A2), wherein the first axis (A1) encloses an acute angle (α) with the transverse direction (Q) of the needle.
2. Knitting machine needle according to claim 1, characterised in that the cross-section (23) is oriented on an angle to the transverse direction of the needle at an acute angle (α) amounting to between 20° and 40°.
3. Knitting machine needle according to claim 1, characterised in that the acute angle (α) varies along the hook (17).
4. Knitting machine needle according to claim 1, characterised in that the acute angle (α) is constant along the hook (17).
5. Knitting machine needle according to claim 1, characterised in that the hook (17) has an arc-shaped section, which has the oval cross-section (23) throughout.
6. Knitting machine needle according to claim 1, characterised in that the oval cross-section (23) is configured on a hook head section (17a).
7. Knitting machine needle according to claim 1, characterised in that the direction of inclination of the first axis (A1) is defined in dependence on the running direction of the needle.
8. Knitting machine needle according to claim 1, characterised in that the acute angle (α) is open towards a thread feed side of the knitting machine needle.
9. Knitting machine needle according to claim 1, characterised in that the oval cross-section (23) is an elliptic cross-section.
10. Knitting machine needle according to claim 8, characterised in that the first axis (A1) is the large elliptical axis and the second axis (A2) is the small elliptical axis.
11. Knitting machine needle according to claim 1, characterised in that the hook (17) has a point (18), and that the oval cross-section (23) decreases towards the point (18) of the hook (17).
12. Knitting machine needle according to claim 11, characterised in that the point (18) has a round cross-section.
13. Knitting machine needle according to claim 1, characterised in that a latch (19) is arranged in the vicinity of the hook (17).

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