This application claims the priority of European patent application No. 07 002 185.2 filed Feb. 1, 2007, the subject matter of which, in its entirety, is incorporated herein by reference.
The invention relates to a gripper for a tufting machine, in particular to a gripper for the production of so-called “cut-loop pile”, also referred to as cut pile.
Tufting machines are used, for example, for the production of carpets/carpeting. In most cases, said machines comprise a table, above which a needle bar is arranged. This needle bar bears a plurality of tufting needles that are disposed to punch a pile thread through the textile support material that is intermittently transported across the table, said support material being referred to as the backing. A bar provided with grippers is provided under the table. With each punch of the tufting needles, the grippers insert loops formed of the tufting threads and hold said loops in place underneath the backing. In order to produce cut pile, knives are provided, said knives being held on a knife bar. These knives are moved toward the grippers and cut the loops held on said grippers.
Usually, appropriate grippers that are provided for the production of cut pile have a cutting insert that acts as a counterpart to the knife. Such a counterpart has been disclosed, for example, by document DE 23 41 567 A1 or also by document DE 28 23 408. In so doing, the gripper, in each case, consists of a flat gripper body that has a cutout for a cutting insert. The cutting insert consists of hard metal. A solder connection is used to secure said insert to the gripper body.
The hard metal insert and the gripper body display different wear resistance properties as well as different stiffness and thermal expansion properties, which can lead to problems.
Considering this, it is the object of the invention to produce an improved gripper for tufting machines.
The above object generally is achieved according to the invention with a gripper for a tufting machine which gripper comprises a gripper body with a gripper section for picking up thread loops, and a cutting insert set into a recess of the gripper body and being secured in the cutout in a form-closed manner.
The gripper in accordance with the invention comprises a gripper body with a cutting insert that is secured in a form-closed or force-closed manner in the appropriate cutout of the gripper body. The cutting insert is held in the cutout by positive-acting fastening means, whereby, however, both elements, i.e., the cutting insert and the gripper body, are allowed to behave consistent with their respective inherent elasticity and thermal expansion properties. The cutting insert and the gripper body are in contact with each other along a separating joint, whereby they are not connected to each other in said separating joint. Thus, micro-movements are possible. Consequently, a given elasticity of the gripper body is not reduced by the relatively stiffer cutting insert. Likewise, different coefficients of thermal expansion cannot lead to a bending of the gripper under conditions of temperature changes.
It is also advantageous that the gripper can be manufactured without a soldering process. Consequently, the gripper and/or the cutting insert are not subjected to any thermal stress. In particular, the cutting insert and the gripper body can be machined separately with the method that is suitable for their materials and can be exposed to corresponding treatment processes. In particular, they can be thermally treated individually separate from each other. The cutting insert, which is preferably made as a hard metal insert, is not damaged by the effect of heat as occurs during hard-soldering. The hard metal insert can be connected to the base body of the gripper without additional substances such as adhesives or solder, or any fluxing agent or similar chemicals. In addition, the gripper bodies and/or the hard metal inserts can be provided with coatings that are formed at low temperatures and do not tolerate high tempera rues. Furthermore, it is possible to provide the gripper body and the cutting insert with various coatings. For example, the gripper body may be provided with a coating that displays good sliding properties in order to reduce wear of the tufting needles, for example. Such coatings are Teflon coatings, for example. They also improve the sliding properties of the tufting thread. In contrast, the cutting insert may be provided with a layer to increase wear resistance. Such a coating may be, for example, a metallic hard material layer, a ceramic layer or the like.
The cutting insert preferably has cutouts on at least two opposing locations, whereby projections on the gripper body project into said cutouts. The cutouts may be limited by surfaces that are inclined relative to the flat sides. These inclined surfaces are preferably oriented at an angle of 40° to 70° relative to said flat side and define a free space into which the material of the gripper body may be stamped or pressed.
Additional details of advantageous embodiments of the invention are the subject matter of the drawings, the description or of the claims. In so doing, the description is restricted to essential aspects of the invention and other situations. The drawing is to be viewed as supplementary and discloses additional details. The drawings show exemplary embodiments of the invention.
The gripper 3 shown separately, in detail, in
The loop-pickup section 15 has a straight edge 19 or narrow side, on which the loops 20 may slide, as is obvious from
The cutout 22 preferably has an essentially uniform depth. Its contour corresponds to that of a rectangle with rounded corners, with a small rectangular piece taken off said rectangle by the edges 19, 21. Consequently, the recess or cutout 22 has a first longer narrow section 23 and a second shorter wider section 24.
Seated in the recess 22 is a cutting insert 10 such as is obvious from
Referring to another (not illustrated) embodiment of a cut-pile looper, the flat side 11, which does not contain the cutout 22, has the inclined surface 28.
As is obvious from
It is also possible for the cutting edge 29 of the cutting insert 10 to project beyond the edge 19 of the gripper body 9. This is indicated in
The contour of the cutting insert 10 corresponds to the edge of the cutout 22. Consequently, the cutting insert 10 is seated, essentially without play, in the cutout 22. In order to fasten the cutting insert, said cutting insert has cutouts 33, 34 in its holding section 32, as is shown by
In order to mount the cutting insert 10, the gripper body 9 is wedged over the cutting insert 10. To achieve this, the edge regions of the cutout 22 are plastically deformed so as to reach over the inclined surfaces 35, 36. The thusly formed deformation regions 37, 38 thus hold the cutting insert in a form-closed manner in the cutout 22. This is particularly obvious from
The so-far described gripper 3 is disposed to operate as follows:
During operation, one end 16 of said gripper picks up loops 20 that mover over the edge 19. To do so, the gripper bar 2 is rhythmically moved, as a rule. The loops 20 move onto the cutting edge 29 of the cutting insert 10. There, they are cut open by knives 6 that are also rhythmically moved. In so doing, the knife 6 can move, e.g., over the inclined surface 27; this prevents said knife from impacting blunt on an edge of the cutting insert 10.
As mentioned, the gripper body 9 and the cutting insert 10 may consist of different materials. In addition, they may have different coatings. For example, the gripper body 9 may be provided with a friction-reducing coating of synthetic material, for example, a Teflon coating. In contrast, the cutting insert 10 may be provided with a wear-minimizing coating, for example, a metallic hard coating such as titanium nitride, titanium carbide or the like.
Referring to the above-described exemplary embodiment, the cutting insert 10 is secured in axial direction in the cutout 22 in that the cutting insert 10 is fitted exactly into the cutout 22. As is shown by
In the vicinity of the edge 41, the edge of the cutout 17 is provided with an inclined surface 48, as is obvious from
Referring to the embodiment shown by
The inclined surface 48 prevents the thread 47 from becoming caught on the edge 41 or on the rim of the cutout 17. In addition, the cutout 17 has a rounded wall section 49 that terminates in the edge 19. Furthermore, this chamfer or rounding 49 also prevents the thread from becoming caught or damaged.
A gripper 3 for a tufting machine comprises a gripper body 9 having a cutout 22 for a cutting insert 10, said cutting insert preferably consisting of a hard metal. Connecting means acting in a form-closed manner are provided for the connection of the cutting insert 10 with the gripper body 9. In their simplest embodiment, said connecting means are formed by the deformation regions 37, 38 that are provided on the gripper body 9 and that reach around matching cutouts 33, 34 of the cutting insert 10.
It will be appreciated that the above description of the present invention is susceptible to various modifications, changes and modifications, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.
Number | Date | Country | Kind |
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07002185 | Feb 2007 | EP | regional |
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7296524 | Beverly | Nov 2007 | B2 |
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3709977 | Oct 1988 | DE |
4315802 | Nov 1994 | DE |
767333 | Jul 1934 | FR |
1473511 | Mar 1967 | FR |
2393096 | Dec 1978 | FR |
782079 | May 1955 | GB |
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Number | Date | Country | |
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20090107371 A1 | Apr 2009 | US |
Number | Date | Country | |
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Parent | 12010961 | Jan 2008 | US |
Child | 12076441 | US |