EP1953289A1 - Hook for a tufting machine - Google Patents

Abstract

The hook (3) has a hook body (9), which includes a hook section (15) for retaining thread loops (20). A blade insert (10) is inserted into a recess of the hook body, and is locked in the recess in a form-fitted manner by projections, where the projections are formed at the hook body. The projections are formed as deformation areas (37, 38) at the hook body by a transforming process. The blade insert is formed with two flat sides by a body, which is provided with recesses (33, 34) in two points, where the insert projects over the hook body.

Description

The invention relates to a gripper for a tufting machine, in particular a gripper for the production of so-called cut-loop pile which is also referred to as Schneidflor.

Tufting machines are used for example for carpet production. Most of them have a table, above which a needle bar is arranged. This carries a variety of tufting needles, which serve to pierce a pile thread through a gradual guided over the table textile backing material, which is referred to as backing. Under the table there is a bar with grapples. The grippers go in with every stitch of the tufting needles The tufted loops formed and hold them below the backing. For the production of cut-pile (cutting pile) serve knives, which are held on a knife bar. They are moved towards the grippers and cut open the loops held on the grippers.

It is customary to provide corresponding gripper provided for the production of Schneidflor with a cutting insert, which serves as a counterpart for the knife. Such a is, for example, the DE 23 41 567 A1 or even the DE 28 23 408 refer to. The gripper consists of a flat gripper body, which has a recess for a cutting insert. The cutting insert is made of carbide. It is secured by means of a solder connection to the gripper body.

The carbide insert and the gripper body not only have different wear resistance but also different stiffnesses and thermal expansions, which can lead to difficulties.

On this basis, it is an object of the invention to produce an improved gripper for tufting machines.

This object is achieved with the gripper according to claim 1:

The gripper according to the invention has a gripper body with a cutting insert, which is secured positively or non-positively in the corresponding recess of the gripper body. The cutting insert is held by positively acting fastening means in the recess, but with both elements, ie the cutting insert and the gripper body is allowed to behave according to its own inherent elasticity and thermal expansion. The cutting insert and the gripper body abut each other along a parting line, but they are not connected to each other in the parting line. So micro-movements are possible. A given elasticity of the gripper body is thereby not reduced by the comparatively stiffer cutting insert. Also, different thermal expansion coefficients can not lead to a bending of the gripper with temperature change.

It is also advantageous that the gripper can be produced without soldering. This prevents any heat load on the gripper and / or the cutting insert. In particular, the cutting insert and the gripper body can be processed separately with the respectively appropriate to their materials process and exposed to appropriate treatment processes. In particular, they can be thermally treated separately from each other separately. Damage to the cutting insert, which is preferably designed as a cemented carbide insert, by heat, as occurs during brazing, is omitted. The cemented carbide insert can be connected to the main body of the gripper without additional substances such as adhesives or solders, as well as fluxing agents or similar chemicals. In addition, the gripper body and / or hard metal inserts can be provided with coatings that arise at low temperatures or tolerate high temperatures. It is also possible to provide the gripper body and the cutting insert with different coatings. For example, the gripper body can be provided with a coating which has good sliding properties, for example to reduce the wear of tufting needles. Such coatings are for example Teflon coatings. These also improve the sliding properties of the tufting thread. In contrast, the cutting insert may be provided with a layer for increasing the wear resistance. Such a coating can be formed for example by a metallic hard material layer, by a ceramic layer or the like.

The cutting insert preferably has recesses, at least at two opposite points, into which projections projecting on the gripper body protrude. The recesses may be limited by obliquely oriented to the flat sides surfaces. These inclined surfaces are preferably oriented at an angle of 40 ° to 70 ° to the flat side and define a free space can be embossed or pressed into the material of the gripper body.

Fig. 1

eine Tuftingeinrichtung mit Greiferbarre in schematisierter Darstellung,

Fig. 2

einen Greifer, der Greiferbarre nach Fig. 1 in einer ausschnittsweisen Perspektivansicht,

Fig. 3

den Greifer nach Fig. 2 in einer Ansicht von unten,

Fig. 4

den Greifer nach Fig. 2 ohne Schneideinsatz in einer Seitenansicht,

Fig. 5

den Greifer nach Fig. 4 mit Schneideinsatz in einer Seitenansicht,

Fig. 6

den Greifer nach Fig. 5, geschnitten entlang der Linie VI-VI,

Fig. 7

einen vergrößerten Ausschnitt der Fig. 6 und

Fig. 8

eine abgewandelte Ausführungsform des Greifers ähnlich Fig. 2 in perspektivischer Darstellung.

Further details of advantageous embodiments of the invention are the subject of the drawings, the description or claims. The description is limited to essential aspects of the invention and other conditions. The drawing is supplementary and reveals more details. In the drawings, embodiments of the invention are illustrated. Show it:

Fig. 1

a tufting device with gripper bar in a schematic representation,

Fig. 2

a gripper, the gripper bar after Fig. 1 in a fragmentary perspective view,

Fig. 3

the gripper after Fig. 2 in a view from below,

Fig. 4

the gripper after Fig. 2 without cutting insert in a side view,

Fig. 5

the gripper after Fig. 4 with cutting insert in a side view,

Fig. 6

the gripper after Fig. 5 , cut along the line VI-VI,

Fig. 7

an enlarged section of the Fig. 6 and

Fig. 8

a modified embodiment of the gripper similar Fig. 2 in perspective view.

In Fig. 1 a tufting system 1 is illustrated, to which a gripper bar 2 with many parallel juxtaposed grippers 3, a needle bar 4 with many held parallel to each other tufting needles 5 and knife 6, which are used for the production of Schneidflor. Over the gripper bar 2, a backing or carrier material 7 is guided, into which 5 pile threads 8 are inserted by means of the tufting needles. The grippers 3 are identical to each other. Hereinafter, a gripper 3 will be described as representative of all others.

The in Fig. 2 separately illustrated in detail gripper 3 has a gripper body 9 and a cutting insert 10. The gripper body 9 and the cutting insert 10 further go out of the Fig. 3 to Fig. 6 out. As can be seen, the gripper body 9 is a flat part with two side surfaces 11, 12 (FIG. Fig. 3 ), which are formed substantially flat and parallel to each other. At the bottom, the gripper has a narrow flat side 40, which connects the side surfaces 11 and 12 with each other. The gripper body 9 has a holding section 13 (FIG. Fig. 4 ), a central portion 14 and a loop receiving portion 15. The underside 40 extends over these sections 13, 14 and 15. In the region of the middle section 14, the underside 40 may be slit. The bottom 40 thus consists of several sections which are offset from one another. The holding portion 13 and the loop receiving portion 15 extend from different sides of the central portion in opposite directions away from each other. While the gripper body 9 in the region of the central portion 14 and the holding portion 13 has a uniform thickness, it may be formed at its loop receiving portion 15 is slightly thinner, as seen from Fig. 3 evident. It thus tapers in the loop receiving section 15 towards its end 16. At the loop receiving portion 15, for example, a recess or recess 17 may be provided on the side surface 11 in order to avoid the so-called "J-cut". "J-Cut" is understood to mean the different lengths of leg of a slit loop. In order to produce a pile in which the legs of a cut sling are the same length, ideally the knife would have to cut the sling exactly in the middle of the underside 40 of the looper body. This is not technically feasible. The interface at which the knife 6 contacts the cutting insert 10 and cuts the loop is offset with respect to the center of a loop. To keep this offset as small as possible, the gripper body 9, the recess 17. It may be in the form of a surface, which is arranged starting from the side surface 11 and ending in the bottom 40 at an angle to the side surfaces 11 and 12, may be formed. The central portion 14 may be provided with a guide recess in the form of a narrow deep longitudinal groove 18 in which a slide (not shown) is mounted longitudinally displaceable. The slider is used in the production of loops in the level-cut loop application and covers for this purpose, in the front-most extended position, the end 16 of the gripper 3.

The loop receiving portion 15 has a straight bottom edge 19 on which the loops 20 can slide as shown Fig. 1 seen. The edge 19 merges in a short rounding into an edge 21 which forms the frontal end of the middle section 14. On one side of the gripper body 9 is a side surface 12 passing through recess 22 (FIG. FIG. 4 ) formed on both the edge 19 as well as adjacent to the edge 21. The recess 22 is relatively flat. Their depth is less than half the thickness of the gripper body 9. Between the recess 17 and the recess 22 remains a thin web. This consists of the material of the integrally formed gripper body 9. The recess 17 and the recess 22 are spaced apart and do not merge into one another.

The recess 22 preferably has a substantially uniform depth. Its outline corresponds to that of a rounded at its corners rectangle, which is separated by the edges 19, 21, a smaller rectangular piece. Thus, the recess 22 has a first longer narrow portion 23 and a second shorter wider portion 24.

In the recess 22 sits a cutting insert 10, as he from the Fig. 2 and 5-7. This cutting insert 10 is preferably made of a different material than the gripper body 9. While the gripper body 9 may for example consist of a flexible steel or of another, eg also non-metallic material, the cutting insert is preferably made of hard metal or other wear-resistant material, such as Ceramic, formed. It has two flat sides 25 and 26, of which the flat side 25 rests against the bottom of the recess 22. The other flat side 26 lies outside and closes off with the side surface 12 (FIG. FIG. 5 ). It may also protrude slightly over the side surface 12. In particular, it is advantageous if the cutting insert 10 has a ramp-like inclined surface 27 at its end pointing towards the free end of the loop receiving section 15. Preferably, this inclined surface 27 is aligned with a level-cut looper with an inclined surface 28 of the loop receiving portion 15. The stepless transition of the two inclined surfaces 28 and 27 prevents each other that the pile yarn forming the loop, when sliding from the front end 16 of the gripper body 9 in the region of the cutting insert 10, at the leading edge 41 is skewered and damaged. With the inclined surface 28 of the loop receiving portion 15 of a smaller thickness to a greater thickness over, in particular Fig. 3 shows.

In another embodiment (not shown), a cut-pile looper, the flat side 11, which does not include the recess 22, the inclined surface 28.

The cutting insert 10 has a cutting edge 29, which consists of the Fig. 2 and 5 can be seen and the course of which follows the course of the edge 19. The cutting edge 29 merges into a further edge portion 30, the course of which substantially follows that of the edge 21. Thus, the cutting insert 10 has a first, forward portion 31, which may be considered a cutting portion, and a second, rear portion 32, which may be considered a retaining portion.

It is also possible that the cutting edge 29 of the cutting insert 10 projects beyond the edge 19 of the gripper body 9 and thus protrudes therefrom. This is in FIG. 5 indicated. In this case, the cutting edge 29 has a ramp 39 to form a stepless transition to the edge 19.

The outline of the cutting insert 10 coincides with the edge of the recess 22. Thus, the cutting insert 10 sits substantially free of play in the recess 22. For attachment of the cutting insert has this at its holding portion 32 recesses 33, 34, see Fig. 2 and Fig. 5 , The recesses 33, 34 are formed for example by inclined to the flat side 26 arranged inclined surfaces 35, 36. The inclined surfaces 35, 36 close to the flat side 26 an angle of preferably 40 ° to 70 °. The recesses 33, 34 are arranged on opposite sides of the holding portion 32.

For fastening the cutting insert 10, the gripper body 9 is caulked to the cutting insert 10. For this purpose, edge regions of the recess 22 are plastically deformed in order to engage over the inclined surfaces 35, 36. The deformation regions 37, 38 thus formed thus hold the cutting insert 10 in a form-fitting manner in the recess 22. This is especially the case 6 and 7 which reveals a greatly enlarged view. At a Einpresstiefe T, for example, 0.05 mm and a resulting projection B of the deformation region 37 on the inclined surface 35 results in a permanent and secure positive locking of the entire cutting insert 10. It is sufficient if the length of the deformation regions 37, 38, for example, only approximately two-thirds of the length of the rear wide portion 32 of the cutting insert 10 corresponds.

The gripper 3 described so far operates as follows:

In operation, he takes with his end 16 slings 20, which run over the edge 19. For this purpose, the gripper bar 2 is usually moved rhythmically. The loops 20 reach the cutting edge 29 of the cutting insert 10. There they are cut by the likewise correspondingly rhythmic moving knife 6. The knife 6 can eg over the Bevel 27 run, thereby preventing it butts against an edge of the cutting insert 10.

The gripper body 9 and the cutting insert 10 may, as mentioned, consist of different materials. They can also be coated differently. For example, the gripper body 9 may be provided with a friction-reducing plastic coating, for example a Teflon coating. In contrast, the cutting insert 10 may be provided with a wear-reducing coating such as a metallic hard coating such as titanium nitride, titanium carbide or the like.

In the embodiment described above, the axial securing of the cutting insert 10 is effected in the recess 22, in which the cutting insert 10 fits snugly into the recess 22. It's also possible, like Fig. 2 shows the inclined surface 36 to be limited to a short axial region of the corresponding edge, so that the deformation region 38 assumes an axial securing function for the cutting insert 10. As Fig. 8 illustrated, this measure can also be made for both inclined surfaces 35, 36. For the rest, the previous description applies to Fig. 8 based on the same reference numerals accordingly.

A gripper 3 for a tufting machine has a gripper body 9, which has a recess 22 for a cutting insert 10, preferably made of hard metal. To connect the cutting insert 10 with the gripper body 9 positively acting connection means are provided. These are formed in the simplest embodiment by deformation regions 37, 38 which are formed on the gripper body 9 itself and matching recesses 33, 34 of the cutting insert 10 overlap.

LIST OF REFERENCE NUMBERS

1

Tuftingsystem

2

gripper bar

3

grab

4

needle bar

5

tufting

6

knife

7

support material

8th

pile threads

9

gripper body

10

cutting insert

11

side surface

12

side surface

13

holding section

14

midsection

15

Loop receiving section / gripper section

16

The End

17

recess

18

guide recess

19

edge

20

loop

21

edge

22

recess

23

section

24

section

25

flat side

26

flat side

27

sloping surface

28

sloping surface

29

cutting edge

30

edge portion

31

section

32

section

33

recess

34

recess

35

sloping surface

36

sloping surface

37

deformation zone

38

deformation zone

39

ramp

40

bottom

41

edge

Claims (10)

Gripper (3) for tufting machine,
with a gripper body (9) having a gripper portion (15) for receiving thread loops (20), and
with a cutting insert (10) which is inserted into a recess (22) of the gripper body (9) and secured in a form-fitting manner in the recess (22). Gripper according to claim 1, characterized in that the cutting insert (10) is formed by a body with two flat sides, which is provided at at least two opposite points with recesses (33, 34). Gripper according to claim 2, characterized in that at least one of the recesses (33, 34) by an inclined to the flat sides (26) oriented surface (35, 36) is limited. Gripper according to claim 1, characterized in that the cutting insert (10) is secured in the recess (22) by projections (37, 38) formed on the gripper body (9). Gripper according to claim 4, characterized in that the projections (37, 38) by a forming process to the gripper body (9) are integrally formed. Gripper according to claim 1, characterized in that the cutting insert (10) projects beyond the gripper body (9). Gripper according to claim 1, characterized in that the cutting insert (10) is a cemented carbide insert. Gripper according to claim 1, characterized in that the cutting insert (10) is provided with a hard material coating. Gripper according to claim 1, characterized in that the gripper body (9) is provided with a friction-reducing coating. Gripper according to claim 9, characterized in that the friction-reducing coating is a plastic coating.

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