Textiles: spinning – twisting – and twining – Apparatus and processes – With drafting
Reexamination Certificate
2000-03-29
2001-07-24
Calvert, John J. (Department: 3765)
Textiles: spinning, twisting, and twining
Apparatus and processes
With drafting
C057S328000, C019S150000, C019S246000
Reexamination Certificate
active
06263655
ABSTRACT:
FIELD OF THE INVENTION
Our present invention relates to a method of and to an apparatus for the bundling of the fibers of sliver in a drafting frame of a spinning machine and, in particular, between the output pair of rollers of the drafting frame and the twist-imparting system of the spinning machine. The invention, therefore, relates to a method of making a thread using a drafting frame of a spinning machine and to a method of operating a spinning machine and/or drafting frame to make a thread.
BACKGROUND OF THE INVENTION
The term “sliver” is here used to refer to the fiber band or strip which generally may be drawn from a “can”, is drafted in a drafting frame and is then subjected to a twisting operation in, for example, a ring-spinning station. The drafting frame can be provided all along a ring-spinning frame and, at each ring-spinning station, the sliver is fed to the spinning mechanism through a plurality of pairs of rollers of the drafting frame, emerging at the output pair of rollers.
The fiber band or strip is referred to here as sliver, and can also be referred to as roving, the difference between a roving and a sliver generally being the fact that the roving has a slight twist previously imparted to the fiber band or strip before it enters the drafting frame. The present invention is applicable to roving as well and the term “sliver” as here used is intended to apply to fiber bands or strips which are collections of individual fibers of limited length.
Such fiber bands may be subjected to a bundling between the drafting frame and the twist-imparting mechanism. The purpose of such bundling is to make the strand consisting of a multiplicity of fibers, more compact at the inception of twisting. Fibers which project out of the strand or in directions transverse or at an angle to the main direction of the strand are usually drawn back into the body of the strand by such compaction.
In the so-called double-belt drafting frame of DE 43 23 472 C2, a bundling of the strand is described in which the sliver leaving the output roller pair of the drafting frame is subjected to a suction stream which is applied transversely to the travel direction of the strand over a length of a fiber bundling zone. The strand passes over a row of perforations subjected to suction for this purpose. The size of the perforations determines the width of the bundles and compacted roving.
To reduce the wear of the pressure roller in this latter drafting frame, it is customary to induce an offset of the roving from side to side as it is introduced into the drafting frame. This back and forth motion of the roving is referred to here as a traversing motion, and causes the strand to move back and forth during its passage through the drafting frame transversely to the travel direction. When a suction compaction of the prior art type is applied, this traversing motion must be excluded or means must be provided to enable the row of suction bores to remain effective in spite of the traversing motion. In practice, this can be achieved by guidance of the strand with a funnel-shaped guide or by limiting the traversing motion or by conceding a lack of ability to effectively bundle the strand.
In the double-belt drafting frame of DE 197 22 528, the fiber-bundling zone is provided downstream of the output roller pair of the main drafting region. In this case, a transport means, for example a belt, is provided with the suction perforations which are enlarged in a direction transverse to the transport direction. Thereafter, the strand is subjected to suction from a series of finer perforations.
While this system represents an improvement over earlier arrangements, it is also a compromise because the sizes of the larger and smaller perforations are nevertheless limited with respect to the potential traversing motion and the possible stroke of the traversing action and this system as well limits the traversing width or stroke in the sense previously described.
A spinning machine has also been described (see DE 196 23 824 A1) in which a convergence is generated in the suction zone between two strands. A disadvantage in this system is that it is not possible to exclude an effect of suction from one row of perforations on the other strand which might tend to defeat the compaction effect.
OBJECTS OF THE INVENTION
It is, therefore, the principal object of the present invention to provide an improved method of making a thread utilizing a drafting frame of a spinning machine with fiber bundling in a suction zone downstream of the last pair of drafting rollers whereby the sliver or roving can be optimally compacted or the fibers thereof bundled, without limitation of the traversing motion.
Another object of the invention is to provide a method of operating a spinning machine whereby drawbacks of earlier systems are obviated.
Still another object is to provide a drafting frame and spinning machine combination which has optimum suction bundling of the fiber strand, e.g. the sliver or roving, without restriction on the traversing motion.
SUMMARY OF THE INVENTION
These objects and others which will become apparent hereinafter are attained, in accordance with the invention, in a method of making a thread using a drafting frame of a spinning machine which comprises the steps of:
(a) drafting a sliver with the drafting frame by passing the sliver through a succession of drafting roller pairs to emerge at an output roller pair, the sliver emerging from the output roller pair having a traversing motion back and forth transverse to a direction of feed of the sliver;
(b) bundling fibers of the sliver by contacting the sliver immediately downstream of the output roller pair on only one side of the sliver with a generally flat portion of a belt moving with the sliver in the direction over a length of a bundling zone, the belt having a surface on one side of the belt in contact with the sliver and being formed with a multiplicity of perforations open toward the sliver in an array extending over the length and of a width at least equal to a stroke of the traversing motion, and applying suction to the array of perforations with an elongated suction orifice juxtaposed with an opposite side of the belt, inclined to the direction and shaped so that the suction is applied to the sliver transversely of the direction to draw fibers of the sliver together and bundle the fibers of the sliver over the entire width of the array; and
(c) twisting the sliver following the bundling thereof downstream of the belt into a single thread.
The apparatus of the invention can comprise:
a drafting frame having a succession of drafting roller pairs for drafting a sliver by passing the sliver through the succession of drafting roller pairs to emerge at an output roller pair, the sliver emerging from the output roller pair having a traversing motion back and forth transverse to a direction of feed of the sliver;
means for bundling fibers of the sliver immediately downstream of the output roller pair and including a transport belt contacting the sliver immediately downstream of the output roller pair on only one side of the sliver with a generally flat portion of the belt moving with the sliver in the direction over a length of a bundling zone, the belt having a surface on one side of the belt in contact with the sliver and being formed with a multiplicity of perforations open toward the sliver in an array extending over the length and of a width at least equal to a stroke of the traversing motion, and suction means applying suction to the array of perforations with an elongated suction orifice juxtaposed with an opposite side of the belt, inclined to the direction and shaped so that the suction is applied to the sliver transversely of the direction to draw fibers of the sliver together and bundle the fibers of the sliver over the entire width of the array; and
means downstream of the belt for twisting the sliver following the bundling thereof into a single thread.
The objects of the invention, therefore, are achieved in that in the process the fibers of the fiber-
Artzt Peter
Morgner Jörg
Calvert John J.
Dubno Herbert
Welch Gary L.
Zinser Textilmaschinen GmbH
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