EP2447404A1 - Tufting cutter with bending point - Google Patents

Abstract

The knife (20) has an elongated strip-shaped base body (24), and a cutting edge (36) provided on an end (31) of the base body. A bending joint (27) e.g. spring loaded hinge, is arranged at a distance from the cutting edge. The base body has flat sides that are limited by longitudinal edges (28, 29), where the cutting edge connects the longitudinal edges with each other. The bending joint is formed by a troughed recess (37) in one of the flat sides of the base body. The recess extends over the entire width of the flat side, and comprises a constant cross-section.

Description

The invention relates to a tufting knife for a tufting machine for the production of Schneidflor.

Tufting machines for the production of cutting pile are basically known and have been in use for a long time. For example, the DE 27 45 793 C a tufting machine, to its always the same basic components a Rietblatt with Rietfingern for supporting the planar support material, a bar with tufting needles, which punctures the substrate rhythmically and thereby pulls thread loops in the substrate, a gripper bar with grippers for receiving the generated loops and a knife bar with knives for slicing the loops belong. In the course of the loop forming process, the knife bar and the gripper bar are moved against each other so that each of a knife abuts against the side surface of each gripper, presses against this and then cut with its cutting edge one or more loops received by the gripper. This process only proceeds reliably when the blades are pressed against the flanks of the grippers, so that the resulting cutting gap between the cutting edge of the gripper and the cutting edge of the blade is close to zero.

The knife contact pressure between the knife and the gripper causes wear on the grippers and also on the knives, which limits the service life of the knife and / or gripper. This is especially true when the gripper has a carbide insert, the respect

Messers has increased abrasive action.

For example, from the DE 1 535 764 Tufting gripper and tufting knife are known with soldered carbide cutting body.

In addition, the disclosed DE 28 56 344 the attachment of tufting knives in a knife block to a bar. As can be seen, the knife block is tuned to the thickness of the knife. If knives of higher flexibility and consequently smaller thickness are to be used, the knife block must be changed. This represents a considerable effort.

It is an object of the invention to specify a concept with which the service life of at least one of the tools involved can be increased in the case of tufting devices.

This object is achieved with the tufting knife according to claim 1:

The tufting knife according to the invention has a strip-shaped basic body, at the end of which a cutting edge is formed. At some distance from the cutting edge, a bending joint is formed, which defines a transverse to the main body bending axis. The bending joint divides the main body into two legs, which are connected to each other elastically via the bending joint. One of the legs carries the cutting edge, while the other leg can be anchored to a knife block. The bending joint allows the bending point and thus the position and angular orientation of the leg carrying the cutting edge to be adjusted in a controlled manner. In addition, the contact force between the tufting knife and the gripper can be adjusted as desired, regardless of the thickness of the tufting knife. This is a good control over the Position of the knife and the forces acting on it and on the gripper given. In particular, excessive blade wear and / or excessive gripper wear can be avoided.

The bending joint or the bending hinge is a spring hinge, which not only ensures the mobility of the two legs of the tufting knife against each other, but also acts as a leaf spring. Preferably, the spring hinge is formed integrally with the rest of the base body, i. It consists of the same material as this one and connects seamlessly with it. In principle, however, it is also possible to form the spring hinges as a separate element which is connected to the two legs of the tufting knife, e.g. is connected by laser welding seams or other joining methods.

The one-piece integral design of the bending hinge with the main body is considered as an advantageous embodiment for its simplicity. For example, the resilient portion which forms the spring hinge, have a smaller material thickness than the rest of the base body. It may be formed by a trough-shaped recess which extends from one longitudinal edge of the tufting knife to its other longitudinal edge. The two longitudinal edges may be straight edges or may follow curved, stepped or other contours. The trough-shaped recess or depression can be formed on only one of the flat sides of the tufting knife. It is also possible to attach a trough-shaped depression on both sides. Preferably, the recess extends over the entire width of the flat side, again preferably with a constant cross section.

The recess may have different cross-sectional shapes. Preference is given to the formation of the recess with a rounded bottom, so that the trough expires flat at both edges. For example, From the edge of the trough, the material thickness in the longitudinal direction of the tufting blade is reduced to the center of the trough to rise from there to the next edge again. In the center of the trough, the material thickness of the bending hinge is preferably 30% to 70%, more preferably 40% to 60%, and in the concrete present embodiment 50% of the material thickness of the rest of the body. There are also trough shapes with other contours, e.g. Trapezoid contour possible.

Preferably, the recess has a width to be measured in the tufting knife longitudinal direction, which width is greater than the strip width of the main body to be measured transversely thereto. Further preferably, the recess follows a radius of curvature, which is about twice as large as twice the width of the base body. The width of the base body is measured at the location of the recess from the longitudinal edge to the longitudinal edge of the base body. In addition, the distance of the center of the recess from the cutting edge is preferably less than half of the radius of curvature and greater than one third of the same.

With this dimensioning is achieved with a tufting knife with the usual thickness, such as 0.8 mm, using conventional materials such as steel, a flexibility that leads on the one hand to a sufficiently high contact pressure between tufting knife and gripper to secure cutting the recorded loops on the other hand to be avoided to large knife wear or gripper wear. For example, a 0.8 mm thick tufting knife according to the invention provide the same contact pressure as a standard tufting knife with a thickness of 0.6 mm. An advantage is that with a knife holder of 0.8 mm standard by using the provided with the bending joint tufting knife an additional knife block of 0.6 or 0.65 mm is unnecessary, as would otherwise be required for receiving and fixing the softer, thinner knife ,

The tufting knife according to the invention enables a very simple adjustment of the tufting machine. The contact pressure of a tufting knife on the gripper can be adjusted for example by laterally adjusting the knife bar to the gripper bar in the tufting machine. The adjustment must be made so that the tufting knife on the one hand should not run too hard on the opposite gripper, on the other hand, a secure cutting function must be guaranteed. For hard tufting knives, this setting must be very sensitive, so that the contact pressure is neither too great nor too small. It is difficult to ensure the correct setting for all knives at the same time and to guarantee compliance with the tolerances over longer operating periods. The provided with the bending joint Tuftingmesser invention are far more tolerant here.

Another advantage of the invention is particularly evident in tufting knives with cutting insert. For example, in the prior art, the contact pressure of the tufting blade can be influenced by the thickness thereof. However, this already comes up against limits, if only knife holder for knives with a certain, eg large strength are available. Furthermore, the measure encounters limits on tufting knives with cutting inserts, eg made of hard metal or ceramic. Such tufting knives consist of a carrier with a pocket or a recess for receiving the cutting insert. If the carrier is too thin, it will be weakened too much at the receiving of the cutting insert, which can lead to premature failure. The bending joint of the tufting knife according to the invention makes it possible in particular to make thicker tufting knives flexible with a cutting insert, so that the knife pressure can be reduced to the value of the next thinner knife. The type of knife holder can remain the same.

In addition, the bending stresses in the tufting knife are concentrated on the bending joint and effectively kept away from the most brittle cutting inserts so that neither their loosening nor their crack or break occurs.

• Figur 1 eine Tufting-Vorrichtung, in Seitenansicht in Prinzipdarstellung,
• Figur 2 die Tufting-Vorrichtung nach Figur 1, in Vorderansicht,
• Figur 3 ein Tuftingmesser, in Seitenansicht,
• Figur 4 ein Tuftingmesser, in Rückansicht,
• Figur 5 einer vergrößerten, nicht maßstäblichen Darstellung des Biegegelenks des Tuftingmessers,
• Figur 6 und 7 abgewandelte Ausführungsformen des erfindungsgemäßen Tuftingmessers, in ausschnittsweiser Vorderansicht.

Further details of advantageous embodiments of the invention can be taken in the drawing of the description and dependent claims. Show it:

• FIG. 1 a tufting device, in side view in schematic representation,
• FIG. 2 the tufting device after FIG. 1 , in front view,
• FIG. 3 a tufting knife, in side view,
• FIG. 4 a tufting knife, in rear view,
• FIG. 5 an enlarged, not to scale representation of the bending joint of the tufting knife,
• FIGS. 6 and 7 modified embodiments of the tufting knife according to the invention, in a sectional front view.

In FIG. 1 a tufting apparatus 10 is illustrated which is used to make tufted material such as carpet. This consists of a carrier material 11 through which 12 loops 13, 14, 15 and 16 are stung by means of tufting needles, which are to form the pile 11 to be produced on the carrier material. While the carrier material rests on a Rietblatt with Rietfingern 17, the loops 13, 14, 15 and 16 are received by a gripper 18. This sits with other congruent and identical grippers in modules or directly to a gripper bar 19, which synchronously in the power stroke to the tufting needles 12 for receiving the newly formed during insertion into the carrier material 11 loop (13, 14, 15, 16) to be moved. The tufting needles 12 are held in large numbers on a corresponding not further illustrated needle bar.

With the grippers 18 Tuftingmesser 20 cooperate, which are held on a knife bar 21. The knife bar 21 is moved against the gripper bar 19 so that the knives cut 20 existing, sitting on the gripper 18 loops, whereby the desired cutting pile is formed. FIG. 1 shows two such cut slings 22, 23rd

FIG. 2 illustrates the tufting device 10 in front view, wherein the representation of the gripper 18, the tufting knife 20 and the knife bar 21 is reduced. Because the grippers 18 are identical to each other, reference is made to each gripper 18 individually as well as to the grippers 18 in their entirety by the same reference numerals. The same applies to the knives 20.

As can be seen, each knife 20 has a base body 24, to which a holding leg 25, a cutting leg 26 and an interposed bending joint 27 are included. The bending joint 27 merges seamlessly into the adjoining legs 25, 26 and consists of the same material as these. It is generally formed in all embodiments described below by a zone of reduced material thickness. Regardless of the bending joint 27 may also be formed as a separate element, for example a spring plate section, which is connected to the adjoining legs 25, 26, for example by welding points or welds.

The tufting knife 20 is in FIG. 3 separately illustrated. Its strip-shaped main body 24 has two in the present embodiment straight longitudinal edges 28, 29 which extend from a holding block-side end 30 to a cutting edge-side end 31. The longitudinal edges 28 may be straight as shown or may have different shapes, including, for example, corners, steps, waves or other contours.

The base body 24 preferably consists of a strip-shaped sheet metal section, of a suitable metal or similar resilient material. Between its flat sides 32, 33 (see FIG. 4 ), a thickness 34 is to be measured, which is substantially smaller than the width 35 to be measured between the longitudinal edges 28, 29.

At the end 31, the tufting knife 20 is provided with a cutting edge 36, which may be straight, wavy, serrated or formed as shown one or more angled. The cutting edge 36 is preferably arranged on the in use the gripper 18 facing side of the tufting knife 20. It can be produced by providing the base body 24 with an obliquely arranged end face at its front end 31, which extends for example, with the flat side 32 meets the cutting edge 36.

The bending joint 27 is preferably formed by a depression or trough-shaped recess 37, which extends transversely to the longitudinal direction of the tufting knife 20 via one of its flat sides 32, 33. The longitudinal direction of the tufting knife 20 is determined by the longitudinal edges 28, 29. The recess 37 may extend as shown at right angles to the longitudinal direction. The edges 38, 39 of the recess 37 are recognizable at right angles to the longitudinal edges 28, 29 oriented. They can also be oriented at an acute angle to the longitudinal direction, as in FIG. 3 indicated by dashed lines.

The bending joint defines a hinge axis 40 that is transverse to the longitudinal direction of the tufting knife 20. As shown, it can stand at right angles or at an acute angle to the longitudinal direction of the tufting knife. The latter is the case when the edges 38, 39, as shown by dashed lines, are not oriented at right angles to the longitudinal direction. By a targeted inclination of the recess 37 thus the bending and twisting conditions of the tufting knife 20 can be adjusted specifically.

The recess 37 preferably follows an arcuate curvature, as in particular from FIG. 4 is apparent. The radius R, with which the bottom of the recess 37 is curved, is preferably two to three times as large as the width 35 of the tufting knife 20. The distance of the center of the recess 37 from the cutting edge 36 is preferably less than half of the rounding radius R, and greater than a third of it. The center of the recess 37 is located centrally between the edges 38, 39 and approximately corresponds to the position of the hinge axis 40. The edges 38, 39 are those Lines in which the curved bottom of the recess 37 meets the flat side 33. As a reference point for distance measurement to the cutting edge whose center is 41 (see FIG. 3 ).

The tufting device 10 described so far operates as follows:

In operation, the gripper bar 19 and the knife bar 21 are moved relative to one another such that the tufting knife 20 perform a cutting movement towards the lower edge of the gripper 18. Here, the tufting knife 20 put with their flat sides 32 to the gripper 18 and slide along it. They are flexibly deformed and clamped against the side surface of the respective gripper 18, wherein the bending joints 27, as shown FIG. 2 can be seen, yield elastically and thereby resiliently generate the desired contact force between the tufting knife and the gripper 18. The legs 25, 26 deform less or not. The deformation is substantially concentrated on the bending joint 27. In FIG. 5 this is exaggerated again.

In the bending joint 27, ie in the region of the recess 37, the thickness 34 is reduced at the thinnest point to a minimum thickness 42 which is to be found in the middle of the recess 37. This location of the minimum thickness 42 determines the position of the hinge axis 40. The flexure 27 provides a desired high compliance of the tufting blade 20. The leg 26 can flexibly avoid the grippers 18 without thereby generating excessive contact forces. The spring characteristic of the tufting knife is much softer than that of a tufting knife of the same thickness without a bending joint 27. The tufting device 10 is thus much more robust, less sensitive to incorrect settings of the cutting gap and more durable. In particular, the abrasive wear between the tufting blades 20 and the grippers 18 is reduced.

The tufting knives according to the invention can be modified in many ways. For example, the bending joint 27 is preferably arranged on the flat side 33 of the tufting knife 20 remote from the cutting edge 36 (see FIG FIG. 4 ). However, it can also be arranged on the opposite side, such as FIG. 6 suggests. In addition, it may be advantageous to provide corresponding recesses on both flat sides 32, 33. The recesses can be generated by material removal or material displacement. The recesses on both flat sides 32, 33 may have the same or different shapes and / or positions. The edges 38, 39 may be formed as shown straight or curved. For example, the edges 38, 39 at the longitudinal edges 28, 29 have a greater distance from each other, as in a central region.

How further both off FIG. 6 like out FIG. 7 As can be seen, the cutting edge 36 may be formed on a hard material insert 43, for example made of ceramic, hard metal or the like. This can be soldered to the base body 24 of the tufting knife 20 or otherwise connected. For this purpose, the leg 26 may have a corresponding receptacle, for example in the form of a pocket, in or on which the cutting insert 43 is arranged. Otherwise, the previous description applies accordingly in addition.

An improved tufting knife 20 has a bending joint 27 at a distance from its cutting edge 36, from which one leg 26 extends to the cutting edge 36 and another leg 25 to a knife bar 21. The Bend joint 27 ensures a high degree of flexibility of the tufting blade 20 and the maintenance of a desired contact force between the tufting knife 20 and gripper 18 largely independent of the size of the lateral flexion or deflection of the tufting knife 20. This has a strong wear-reducing.

LIST OF REFERENCE NUMBERS

10

Tufting apparatus

11

support material

12

tufting

13-16

wrap

17

reed fingers

18

grab

19

gripper bar

20

tufting

21

knife Barre

22, 23

Sliced loops

24

body

25

holding leg

26

cutting leg

27

bending joint

28, 29

longitudinal edge

30

Holding block side end

31

Cutting edge side end

32, 33

Flat sides of the tufting knife 20

34

Thickness of the tufting knife 20

35

Width of the tufting knife 20

36

cutting edge

37

recess

38, 39

Edges of the recess 37

40

joint axis

R

radius

41

Center of the cutting edge 36

42

minimum thickness

43

cutting insert

Claims (12)

Tufting knife (20) for tufting machine,
with an elongated strip-shaped main body (24),
with a cutting edge (36) formed at one end (31) of the main body (24),
with a bending joint (27) formed at a distance from the cutting edge (36). Tufting knife according to claim 1, characterized in that the bending joint (27) is a spring hinge. Tufting knife according to claim 2, characterized in that the spring hinge in the form of a resiliently formed portion of the base body (24) is formed. Tufting knife according to claim 3, characterized in that the resilient portion has a smaller material thickness (42) than the rest of the base body (24). Tufting knife according to claim 1, characterized in that the base body (24) has two flat sides (32, 33) which are delimited by longitudinal edges (29, 28) and that the cutting edge (36) connects the two longitudinal edges (29, 28) with each other , Tufting knife according to claim 5, characterized in that the bending joint (27) by a trough-shaped recess (37) in at least one of the flat sides (32, 33) of the base body (24) is formed. Tufting knife according to claim 6, characterized in that the trough-shaped recess (37) over the entire width (35) of the flat side (32, 33). Tufting knife according to claim 7, characterized in that the recess (37) has a constant cross section along its length. Tufting knife according to claim 6, characterized in that the recess (37) has a rounded bottom. Tufting knife according to claim 1, characterized in that the minimum thickness (42) of the base body (24) at the recess (37) is substantially half the thickness (34) of the tufting blade (20). Tufting knife according to claim 6, characterized in that the recess (37) follows a radius of curvature (R), which is about twice as large as twice the width (35) of the tufting blade (20). Tufting knife according to claim 1, characterized in that the distance of the center of the recess (37) from the cutting edge (36) is less than half of the radius of curvature (R) and greater than one third of the radius of curvature (R).

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