Textiles: fiber preparation – Working – Carding
Reexamination Certificate
2000-01-12
2001-01-09
Calvert, John J. (Department: 3741)
Textiles: fiber preparation
Working
Carding
C019S113000
Reexamination Certificate
active
06170124
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a card clothing for flats of a card with a carrier element and a plurality of card wires received with at least one received section in the carrier element, wherein each card wire has at least one processing section arranged exposed outside of the carrier element. The invention also relates to a carrier element which can be used for manufacturing such a card clothing.
2. Description of the Related Art
A card is used in manufacturing yarn for parallelizing the individual fibers of a raw material consisting of inordinate fibers. For this purpose, a card usually is essentially composed of a swift formed essentially in the form of a circular cylinder and a number of flats which are movable along a predetermined path relative to the swift extending approximately parallel to the circumferential surface of the swift. For processing the fibers of the raw material, the swift has on its circumferential surface a swift clothing formed, for example, by sawtooth wires, while the flats are equipped with flat clothings along the predetermined path on the side facing the swift. These flat clothings can also be constructed in the form of sawtooth wire sections which extend parallel to the predetermined path. However, also used for this purpose are flat clothings in the form of card clothings of the above-described type. In comparison to the all-steel clothings formed of sawtooth wire sections, the card clothings of the above-described type are distinguished by a substantially lower weight and by significantly lower manufacturing costs. In this connection, the weight of a flat equipped with a card clothing of the above-described type may be less than half the weight of a flat with a flat clothing formed from sawtooth wires. This not only results in a significantly lower energy consumption when operating a card, but also in less wear because the movement and guidance of the flats equipped with a card clothing of the above-described type along the predetermined path can take place using particularly low forces. For this reason, particularly when manufacturing inexpensive yarns having low quality requirements, card clothings of the above-described type are increasingly used.
However, it has been found problematic that the web-shaped carrier elements, which are composed of an elastic synthetic material and/or a plurality of fabric layers which are vulcanized together, tear already after a short time in the area of the received sections of the card wires. This is because, during the processing of the fiber material, substantial forces act on the carrier element in the area of the received sections of the card wires. For eliminating this deficiency, it has already been proposed in CH 636 134 to provide the carrier elements of card clothings of the above-described type with web-shaped reinforcement inserts. However, the manufacture of such carrier elements is comparatively very expensive, so that the cost reductions to be achieved by the use of these card clothings are at least partially eliminated.
In addition, when using the card clothings of the above-described type, it has been found to be a disadvantage that a large quantity of short fibers accumulates in the area of the processing sections of the card wires; for ensuring a reliable operation of the card, this requires a frequent cleaning of the card clothings of the flats.
SUMMARY OF THE INVENTION
In view of the above-described problems in the state of the art, the invention is based on the object of providing an inexpensive and low-wear card clothing of the above-described type which is able to ensure a reliable operation of a card in a simple manner.
In accordance with the present invention, this object is met by a further development of the known card clothings of the above-described type, in which at least in one of the card wires the received section received in the carrier element has at least the same length as the processing section which is exposed outside of the carrier.
This invention is based on the finding that the substantial wear observed when using the known card clothings is primarily due to the lever length between the processing tip arranged at the end of the processing section facing the carrier element and the carrier element, wherein the lever length is large in comparison to the length of the received section available for transmitting the processing forces acting on the processing section to the carrier element. In the card clothing further developed in accordance with the present invention, the reduction of the length of the processing section to a length corresponding at most to the length of the received section results in a change of the force transmission ratio between the processing forces acting on the processing section of the card wires and the received section of the card wires available for introducing these processing forces into the carrier element, wherein this change of the force transmission ratio is advantageous with respect to the wear of the card clothing. Consequently, tearing of the carrier element in the area of the received sections of the card wires received in the carrier element can be reliably prevented in case of the usually occurring processing forces even without the use of additional reinforcement inserts in the carrier element. Therefore, the further development of the known card clothings according to the invention can ensure a high resistance to wear in an economical manner.
Moreover, the reduction of the length of the processing sections additionally reduces the quantity of the short fibers accumulating during the operation of a card in the area of the card clothings according to the invention. This is due to the fact that generally only those short fibers can accumulate in the area of the card clothings whose length only slightly exceeds the length of the processing sections so that the reduction of the length of the processing sections results in a reduction of the short fiber portion separated by the card from the raw material. This result of the reduction of the length of the processing sections of the card wires proposed in accordance with the invention appears to be a disadvantage at first glance. However, it has been found, particularly when manufacturing inexpensive yarns with low quality requirements, that the reduced separation of short fibers and contamination from synthetic fibers with low contamination can be readily accepted in view of the advantages achieved as a result with respect to the infrequently required cleaning of the card clothings of the flats.
With respect to the resistance to wear of the card clothings according to the invention, it has been found to be particularly advantageous if the ratio of the length of the received section of the card wires received in the carrier element to the length of the processing section exposed outside of the carrier element is at least 3:1, preferably at least 5:1.
For reducing the quantity of the short fibers accumulating during the operation of a card in the area of the card clothings of the flats, it has been found particularly advantageous if the length of the processing sections exposed outside of the carrier element is shorter than 3 mm, preferably shorter than 2 mm, particularly preferably shorter than 1.5 mm.
It has been found to be particularly advantageous with respect to production technology if the received sections of the card wires extend through the carrier element starting from the rear side of the carrier element facing away from the processing section to the front side of the carrier element facing the processing section; this is because, when manufacturing card clothings according to the invention, the card wires can then be inserted—without damaging the front side of the carrier element which generally faces the swift during the processing of the fiber material—to such an extent into the rear side of the carrier element until the processing section emerges at the front side of the carrier element.
For securing the card wir
Calvert John J.
Graf + Cie AG
Kueffner Friedrich
Welch Gary L.
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