Textiles: spinning – twisting – and twining – Apparatus and processes – With drafting
Reexamination Certificate
2001-03-07
2001-12-04
Calvert, John J. (Department: 3765)
Textiles: spinning, twisting, and twining
Apparatus and processes
With drafting
C057S264000, C019S150000, C019S246000
Reexamination Certificate
active
06324825
ABSTRACT:
FIELD OF THE INVENTION
Our present invention relates to a drafting frame for a spinning machine and, more particularly for a drafting frame of the type in which the output roller pair of the drafting frame is followed by a compaction zone in which, utilizing suction, a condensing of the drafted sliver is carried out.
BACKGROUND OF THE INVENTION
A drafting frame for a spinning machine is described, for example, in German patent document DE 197 08 410 A1 and has, at the output side of the drafting frame, a fiber bundling, compaction or condensing zone. Between the output roller pair of the drafting frame and a further feed roller pair delivering the drafted and condensed sliver to the spinning machine, a fiber bundling zone is provided. The fiber bundling zone in this system has a suction shoe over which a perforated belt is looped. The suction shoe is subjected to suction from a suction pump and the perforated belt has a row of perforations to which the sliver is exposed to the suction as the belt passes across the shoe and the sliver lies along the belt. The suction draws any outwardly-projecting fibers into and along the sliver to produce the compaction or condensation effect. The suction through the perforations results in an air flow transverse to the displacement of the sliver to direct the fibers inwardly.
Because of the need for the feed roller pair, a retrofitting of the drafting frame of a conventional spinning machine with a compaction unit is expensive and often impractical.
Another compaction system has been described in German patent document DE 198 46 268 A1, corresponding to U.S. Pat. No. 6,108,873. In this construction the drafting frame is provided at its outlet side with a clamping roller which is driven by one of the output rollers of the drafting frame. The latter output drafting roller and the clamping roller may be coupled together by a transmission unit, for example a gear set or a pulley system. This arrangement has the drawback that the transmission elements are sensitive to contamination and fibers or the like can wind up or accumulate therein. Furthermore, any transmission elements of that type may generate lint or particulates which may be disadvantageous.
OBJECTS OF THE INVENTION
It is the principal object of the present invention to provide a relatively simple, reliable and efficient compaction unit for association with a drafting frame for a spinning machine whereby drawbacks of earlier systems are avoided.
Another object of this invention is to provide a drafting frame which can have the advantages of sliver compaction or condensation and whereby the provision of the sliver compactor by retrofitting a drafting frame without such a compactor is facilitated.
Yet another object of this invention is to provide an improved drafting frame for a spinning machine which is free from drawbacks associated with superfluous transmission elements in the region of the drafting frame.
SUMMARY OF THE INVENTION
These objects and others which will become apparent hereinafter are attained, in accordance with the invention, in a drafting frame for a spinning machine which comprises:
a plurality of roller pairs disposed in succession and operating at successively higher peripheral speeds for drafting a sliver, the plurality of roller pairs including an output roller pair delivering a drafted sliver; and
a condensing zone downstream of the roller pairs for receiving the drafted sliver and defined between an upstream first clamping location formed by a nip of the output roller pair engaging the drafted sliver and a downstream second clamping location engaging the sliver between a pressing element of a pneumatic sliver compactor and a peripheral portion of a roller of the output roller pair,
the pneumatic sliver compactor comprising a suction opening and a transport member having a row of perforations passing across the suction opening and over the pressing element for drawing sliver fibers of the drafted sliver inwardly to condense the drafted sliver upstream of the second clamping location.
According to the invention, therefore, the second clamping location utilizes a peripheral portion of one of the output rollers of the drafting frame, i.e. one of the rollers of the output pair, and a pressing element of the compaction unit which bears thereagainst. As a consequence the pneumatic compactor, which can be comprised of a suction shoe and a perforated transport medium, usually a belt, can be made substantially more compact than the compactor of conventional units. Because the compactor of the invention occupies less space, the transport element for the sliver to be compacted can be driven directly by the output rollers of the drafting frame.
According to a feature of the invention, the second clamping location can be formed by a peripheral portion of the upper roller of the output roller pair.
In a drafting frame in which the transport element is looped over two rollers (routing rollers or deflecting rollers), one of the rollers is constituted as a pressing roller and serves as the pressing element for the second clamping location. The pressing roller can be biased by at least one spring against the output roller forming the clamping location. The transport element is thus pressed against the output roller by the spring-loaded routing roller and is driven by the output roller. The routing roller and the output roller forming the clamping location thus so engage the drafted and compacted sliver between them that passage of the twist imparted to the sliver in the spinning machine back into the compaction or condensing zone is precluded.
With the construction of the invention, the fiber bundling zone is defined, on the one hand, between the first clamping location formed by the output roller pair and, on the other hand, by the second clamping location formed between the pressing element on the upper roller of the output roller pair. To facilitate service of the drafting frame, the routing rollers can be paired in a manner similar to the pairing of the upper rollers of the drafting frame. Customarily each weighting arm of the drafting frame carries pairs of the upper rollers which are lowered onto the respective slivers as the latter rest upon the lower rollers.
Alternatively the transport element can loop around the suction shoe and the suction shoe can then form the pressing element defining the second clamping location. Routing rollers can then be eliminated entirely since the suction shoe can be surrounded by the transport element which can be formed as a perforated belt and can have a double function in that it forms the second clamping location as well as serving to carry away the drafted and condensed sliver.
According to another feature of the invention, the pressing element can have a sieve roller provided with a shielding element. The shielding element can limit the suction at the interior of the sieve roller to a portion of the periphery thereof so as to generate the condensing suction and draw air inwardly toward the sliver. The shield, in this case, can be located within the sieve roller.
According to another feature of the invention, the pressing element can be provided with a recess and a hollow shaft having a stationary shielding element. The hollow shaft can be formed with the recess and indeed a plurality of recesses distributed around the circumference of the hollow shaft. The hollow shaft has at least one circumferential groove in which the shielding element can be received. Outwardly of the region of the groove, a perforated transport element, e.g. a belt, can be guided on the hollow shaft.
In embodiments of the invention in which a roller rotates to deliver the sliver to the spinning frame, this roller can be driven by one of the output rollers in a manner analogous to the supply roller of prior art systems. Depending upon the material of the sliver, a compacting spinning may be desirable with so-called oversupply or so-called undersupply of the sliver. For example in the spinning of fibers which are textured and have a crimped texture, the supply spee
Buschluter Detlef
Dinkelmann Friedrich
Löscher Rainer
Olbrich Andreas
Stoll Angelika
Calvert John J.
Dubno Herbert
Welch Gary L.
Zinser Textilmaschinen GmbH
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