Textiles: spinning – twisting – and twining – Apparatus and processes – Receiving twist type
Reexamination Certificate
1999-04-02
2001-03-20
Calvert, John J. (Department: 3741)
Textiles: spinning, twisting, and twining
Apparatus and processes
Receiving twist type
C057S315000, C019S246000, C019S266000, C019S288000
Reexamination Certificate
active
06202398
ABSTRACT:
FIELD OF THE INVENTION
Our present invention relates to a method of and to an apparatus for the production of yarn. More particularly, the invention relates to a method producing a yarn in which roving supplied by a drafting frame is subjected to condensing (compaction) and is then twisted and collected at a spinning station of the spinning machine. The invention also relates to the spinning machine which is used for that purpose.
BACKGROUND OF THE INVENTION
A spinning machine generally comprises a drafting frame and a multiplicity of spinning stations, the drafting frame comprising a number of roller pairs through which the roving passes for drafting or drawing between the roller pairs which can be operated at successively higher peripheral speeds. The lower rollers of the roller pairs may be continuous, i.e. rollers that extend the full length of the drafting frame, while the upper rollers or pressing rollers may be mounted in the weighting or loading arm and can be specific to the particular spinning station. Twinned upper rollers are commonly also provided, i.e. each arm may press two upper rollers against one of the continuous lower rollers.
At each spinning station the roving or, where two or more rovings are supplied to a given station, the plurality of rovings thus supplied are twisted and wound up in a yarn body.
The condensing or compacting system for a roving or slubbing can be provided as described in German patent document DE 44 26 249 A1 or EP 0 635 590 A2. In the first case, the condensing device is in the form of a rotatable cylindrical roller which is provided along its periphery with a row of perforations. The perforations can be maintained under suction and the roller can be referred to as a suction roller. In the EP 0 635 590 A2 publication, the row of perforations is provided on an endless flexible belt and suction can be applied to these perforations as well.
The condensing or compaction operation applies a roving delivered by a drafting frame, has the advantage of drawing the roving together so that when it enters the twisting zone it is substantially more compact than when, as sliver or slubbing, it arrives at the drafting frame. Since the roving before it reaches the twisting zone is more tightly defined by reason of the condensing or compaction steps, the twist tends to jump practically to the nip of the last roller pair in the path of the yarn before the spinning station and the so-called “spinning triangle” can be relatively small. Losses of edge fibers from the yarn can be minimal and the number of fibers which project out of the yarn can be small as well so that the finished yarn has a low degree of hairiness.
OBJECTS OF THE INVENTION
It is the principal object of the present invention to provide an improved method of making yarn of low hairiness and high quality, whereby drawbacks of earlier systems are avoided.
Another object of the invention is to provide a method of producing yarn in which fiber losses during the yarn spinning process are held to a minimum.
It is still another object of the invention to provide an improved spinning machine for the purposes described.
SUMMARY OF THE INVENTION
We have now found that all of these objects can be obtained and yarn of improved quality can be produced when, after drafting of the roving or slubbing, the latter is subjected to a condensing operation as described and the resulting compacted roving is then twisted and collected in a yarn body utilizing a pot-spinning machine. In other words, by providing the condensing device on the spinning machine immediately downstream of the drafting frame or as an integral part of the drafting frame immediately after the last roller pair thereof, we can take advantage of the reduction in peripheral fiber loss and the reduced hairiness of the product.
It has been found further that when, in conjunction with the condensing action, the twisting and winding up of the yarn is carried out on a pot-spinning machine, additional advantages can be obtained. The twisting and winding up of the yarn can be carried out on such a pot-spinning apparatus in a balloonless manner and with reduced yarn tension in the piece of yarn between the point at which the yarn is deposited in the yarn cake in the spinning head and the output roller pair of the drafting frame by comparison with the yarn tension in a ring-spinning machine or the like. This effect of the pot-spinning machine is in addition to or in support of the effect of the compaction of the roving.
According to a feature of the invention the condensing or compaction operation is carried out before twisting is imparted to the roving. According to a feature of the invention the spinning machine can comprise:
a drafting frame for drafting roving to produce drafted roving;
a condensing device downstream of the drafting frame for compacting the roving to compacted roving;
a pot-spinning station receiving at least one of the compacted rovings for balloonless twisting thereof to form a yarn and for collecting yarn in a yarn body.
In this pot-spinning machine, the condensing device can be provided on the drafting frame. The condensing device can be provided with a suction roller, i.e. a hollow rigid rotating body to which suction is supplied at its center and which is formed with a row of perforations applying suction to the roving. Where necessary or desirable, the suction can be applied through a flexible belt guided over a roller and which can be used to support the roving between the output rollers of the drafting frame and the roller about which the belt passes.
The pot-spinning stations can be of conventional construction for pot-spinning machines.
According to the invention, core yarn can be made utilizing the principles described above and mock yarn can be fabricated as well. Reference may be had to our commonly assigned copending application, Ser. No. 09/285,434 filed concurrently herewith and based upon German application 198 15 053.9 filed Apr. 3, 1998.
For the fabrication of a core yarn, core threads should be as much as possible wholly embedded in the roving and the roving should be twisted so that the core yarn is not at all visible in the roving. In conventional core yarn spinning, there are gaps in the cover fibers through which the core yarn or thread may be visible or over which the application of the cover filaments may be incomplete, thereby leading to a reduction in the quality of the resulting core yarn. When a core thread is, in accordance with the invention, embedded in the roving prior to the condensing or compaction step, it has been found that the coverage of the core thread is far more complete and hence the yarn is of higher quality. Indeed, it has been found to be advantageous in this case to feed the core thread to the roving upstream of the condensing or compaction zone and where the roving is still relatively wide as much as possible centrally to the roving. This is especially the case where the core thread is supplied to the roving upstream of the output pair of rollers of the drafting frame. Of course, as an alternative, the core thread can also be fed directly to the condensing or compaction zone. It has been found to be advantageous to feed the core thread to a perforated belt extending from the last roller pair of the drafting frame as part of the condensing or compaction unit and to supply core thread from above or below so that it is delivered to the belt at the point at which the belt undergoes a change in direction proximal to the nip of the last roller pair of the drafting frame.
Alternatively, the belt can be provided at its inlet side with a guide roller so that the core thread is fed between this guide roller and the belt. When the condensing device has a suction roller, the core thread can also be fed to the periphery of the suction roller so that it can be held by suction thereagainst. The core thread also can be delivered to the nip of the last roller pair of the drafting frame.
While each roving can receive a single core thread, it is also possible to supply a plurality of core threads
Dinkelmann Friedrich
Olbrich Andreas
Calvert John J.
Dubno Herbert
Hurley Shaun
Zinser Textilmaschinen GmbH
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