Title of Invention

A DRAFTING UNIT FOR SPINNING MACHINES HAVING A TUNNEL LIKE CONDENSING ZONE

Abstract The invention relates to a drafting unit (1) for spinning machines comprising a driven delivery roller (2), to which two press rollers (3, 4) are arranged, said press rollers (3, 4) forming together with the delivery roller (2) two successive nipping lines (5, 6) between which the fibre strand (11) travels through a condenser (14) supported on the delivery roller(2), having a tunnel-like condensing zone (12), and comprising guiding walls (15) which at least laterally taper in said condensing zone (12), the bottom of said condensing zone (12) being formed by the surface (16) of the delivery roller (2), the condenser (14) contacts the surface (16) of the delivery roller (2) at one or more supporting places (20, 21, 23) only and in that a gap (18) between the guiding walls (15) of the condenser (14) and the surface (16) of the delivery roller (2) in the non- contacting areas has a height (s) which is smaller than the thickness (d) of a single fibre (22) of the fibre strand (11) to be condensed.
Full Text FIELD OF INVENTION
The present Invention relates to a drafting unit for spinning machines comprising
a driven delivery roller, to which two press rollers are arranged, said press rollers
forming together with the delivery roller two successive nipping lines, between
which the fibre strand travels through a condensor disposed on the delivery roller
and having a tunnel-like condensing zone, said condensing zone comprising
guiding walls tapering at least in lateral direction, the bottom of said condensing
zone being formed by a fibre-guiding surface of the delivery roller, said
condensing zone comprising between the condenser and the delivery roller at
least one partition in the form of gap.
BACKFGROUND OF INVENTION
When in a spinning machine a drafted fibre strand is Imparted a spinning twist
directly downstream of the front roller pair of the drafting unit, a so-called
spinning triangle occurs at the nipping line of the front roller pair. This comes
about because the drafted fibre sfrand leaves the drafting unit having a certain
width and is twisted to a thread having a relatively small diameter. The spinning
triangle comprises lateral fibres, which are not properly bound Into the twisted
thread and thus /rontribute little or nothing to the tensile strength of the spun
thread. In recent times, a condensing zone has been arranged downstream of
the drafting zonei of the drafting unit, which condensing zone is In turn bordered
by a nipping line. Only downstream thereof is the thread imparted its spinning
twist. The fibres are bundled or condensed in tlie condensing zone, wliereby tiie
fibre strand is so narrow when it leaves the nipping line furthest down-stream
that the feared ^pinning triangle is no longer noticeably disadvantageous. The
spun thread is then more even, tear-resistant and less hairy.
Very varying arrangements are known for condensing a fibre condensing a fibre
strand. Many of these arrangements function pneumatically. This has the
disadvantage that the energy consumption is very high. Today, however, there
are known arrangements which condense nrtechanically and which do not have
this disadvantage. An arrangement of this type, for example, is sold by the Swiss
firm RotorCraft. Subsequent to a presentation given by Mr. Hans Stahlecker in
Pakistan, a brochure pertaining to this arrangement became known to the
present applicant; on September 17, 2003. The embodiment of the drafting unit
described in this brochure comprises a delivery roller, to which two press rollers
are arranged. Thus the condensing zone is separated.............................................
from the drafting area. The drafting area ends at the nipping line which is
formed by the first press roller. The condensing area is located downstream
thereof, said condensing area extending to the nipping line formed by the second
press roller. The fibre strand is impacted its spinning twist downstream thereof.
In the condensing zone, the fibre strand travels through a condensor disposed
on the delivery roller and comprising a tunnel-like condensing zone, which tapers
in the direction of motion of the fibres. The bottom of the tunnel-like condensing
zone is formed by the surface of the delivery roller itself. The fibre strand to be
condensed therefore travels through a completely enclosed channel, which
comprises two components disposed very closely together. Both components,
namely the delivery roller having a very high precision fluting and the precisely
ground ceramic condensor, are so adapted to each other in such a way that the
partition of the tunnel-like condensing zone is completely closed. Because ths
radius of the condensor underside corresponds exactly to the radius of the
delivery roller, the height of the gap formed at the partition is zero.
The known embodiment, on which the present invention is based, has the
disadvantage that it Is an extremely complicated procedure to ensure the
supporting of the condensor without a gap. The exact matching of the radii of
the delivery roller and the condensor underside requires an extremely expensive
manufacturing process.
OB3ECT OF INVEWTICMi
It is an object of* the present Invention to design the condensor in such a way
that the function is maintained in its entirely, while making the manufacturing
process significantly simpler.
SUMMARY OF INVENTION
This object has been achieved in accordance with the present invention in that
the height of the gap between the condensor and the fibre-guiding surface of the
delivery roller is smaller than the thiclcness of the individual fibres of the fibre
strand to be condensed along the entire length of the condensor, as seen in the
direction of motion of the fibres.
The present invention is based on the Icnowledge that a support without a gap is,
in fact, not necessary. It is sufficient when the gap is smaller than the fibre
thickness along its entire length. This has the advantage that significantly greater
tolerances are permissible in the manufacturing of the components.
The person skilled In the art knows the dimensions of cotton fibres. Therefore 't
Is purposeful when the gap Is narrower than 7 micrometers when processing
cotton. A further advantage arises In that the condensor no longer needs to be
disposed on the delivery roller with Its entire surface. It is sufficient when the
condensor is supported on one, or on a few, supporting places on the delivery
roller. Those surfaces of the condensor which do not come into contact with the
delivery roller can be permitted coarser tolerances as a result.
A further possibility for omitting the difficult matching of radii Is to use a coating.
It is advantageous to make the coating from a material which will be abraded by
the delivery roller. The contour of the condensor will thus be matched exactly to
the delivery roller during running in; any gaps present before running In will
close by themselves and disappear. In the case of the ceramic condensor
described in prior art, this is not possible, because as the condensor is harder
than the delivery roller, the delivery roller will show signs of wear first.
It Is favourable when the gaps are limited to the area of the guiding walls. This
results in the reduction of the high precision area of the underside of the
condensor and thus in the simplification in manufacturing. Outside of this area
the gap between the fibre-gulding surface of the delivery roller and the
condensor can be enlarged. A gap height measuring several times that of the
thickness of the fibres is advantageous In order to prevent pieces of abraded
fibre or broken-off fibres from being nipped.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
These and further objects, features and advantages of the present invention will
become more readily apparent from the following detailed description thereof
when taken in conjunction with the accompanying drawings.
Figure 1 is a side view of the area of the delivery roller and the condensing zone
of a drafting unit.
Figure 2 is an intersectional view of the condensor along the intersectional
surface l-l of Figure 1, whereby the press rollers have been omitted for purposes
of clarity.
Figure 3 Is a greatly enlarged view of the area II of Figure 1,.................................
Figures 4 and 5 are views similar to Figure 3, each of another embodiment of the
condensor underside,
Figure 6 is a view similar to Figure 3 of a variation of the condensor with a
coating,
Figure 7 is an Intersectional view along tiie intersectional surface Ill-Ill of Flfure 1
of the area of the tunnel-like condensing zone.
DETIAL DESCRIPTION OF INVENTION
The drafting unit 1 shown only partly in Figure 1 is part of a spinning machine,
preferably a ring spinning machine. The drafting unit 1 is shown only in the area
of Its driven delivery roller 2 extending continuously in machine longitudinal
direction, that is, In the area of the drafting unit front roller.
Two press rollers 3 and 4 are flexibility pressed against the delivery roller 2. The
press rollers 3 and 4 have a fixed distance from each other. They form with the
delivery roller 2 two nipping lines 5 and 6, the distance between said nipping
lines 5 and 6 belrig smaller than the staple length of the fibres to be spun.
The press rollers 3 and 4 can, in the known way, be joined together with the
corresponding press rollers of adjacent spinning positions to form double press
rollers.
Directly before the run-in to the first nipping line 5, an apron pair is arranged to
the delivery roller 2 and the first press roller 3, said apron comprising a lower
apron 7 and an upper apron 8. The guiding table arranged to the lower apron 7
is denoted by the reference number 9.
A sliver or roving 10 to be drafted is fed to the drafting unit 1 In the direction of
motion of the fibres A. Downstream of the first nipping line 5 lies an essentially
complete drafted fibre strand 11, which is condensed in a tunnel-like condensing
zone 12. Edge fibres should be hereby deposited on the fibre strand 11.
Downstream of the second nipping line 6, a thread 13 forms which is fed in
delivery direction B to a twist device (not shown), for example a ring spindle,
which imparts the thread 13 the necessary spinning twist.
The above mentioned tunnel-like condensing zone 12 is formed by a condenser
14 with Its guiding walls 15, while the fibre guiding surface 16 of the delivery
roller 2.....................................................................................................................'"
forms the bottom. The fibre guiding surface 16 is the outer circumferential
surface of the delivery roller 2, whereby often an existing fluting of the delivery
roller 2 can interrupt the fibre guiding surface 16 by means of its grooves 17.
The guiding walls 15 can be seen In Figure 2, in which a section along the
surface l-l is shown without the press rollers 3 and 4. They are formed in such a
way that the width of the tunnel-like condensing zone 12 tapers in the direction
of motion of the fibres A. The width of the drafted fibres strand 11 at the nipping
line 5 Is thus continually reduced while traveling through the tunnel-like
condensing zone 12 until it reaches the second nipping line 6. Here the
condensed fibre strand 11 is nipped, so that when the twist is imparted, no
spinning triangle of any significant size appears. The desired increased material
utilization is thus achieved, which effects a higher tear resistance and a reduced
hairiness of the thread 13.
Figures 3 to 5 show the greatly enlarged area II from Figure 1. Shown is the
tunnel-like condensing zone 12 and the gap 18, formed by the condensor 14 and
the delivery roller 2 and having a height s, whereby in each Figure a different
variation of the gap 18 is embodied. Figure 3 shows an embodiment in which the
radius of the underside 19 of the condensor 14 is smaller than the radius of the
delivery roller 2. The supporting places 20 and 21 arise herefrom. The radii are
to be chosen in accordance with the present invention In such a way that the
gap height s of the gap 18 dos not exceed the thickness d of a single fibre 22 of
the fibre strand 11 to be condensed. If the delivery roller 2 has grooves 17, the
height s of the gap 18 is defined as the height above the fibre-guiding surface 16
of the delivery roller 2. The thickness d of a single fibre 22 Is the diameter of one
round single firbe. In the case of non-round fibres, the reference d denotes the
smallest possible thickness of the cross section. In Figure 4 a variation is shown
in which the radius of the underside 19 of the condensor 14 is larger than the
radius of the delivery roller 2. In this case, a supporting place 23 is formed,
which has a gap 18 upstream and downstream thereof respectively. It should be
noted that the condensor 14 can tilt around the supporting place 23, when it is
not guided in any other way, and that the height s of the gap 18 can then
become altered. According to the present invention, it must be ensured that
when the condensor 14 is in a titied state, the height 3 of the larger gap 18 is
smaller than the thickness d of a single fibre 22.
Figure 5 shows a variation to the embodiment shown in Figure 3, in which the
underside 19 is not formed as a continuous radius, but rather comprises straight
pieces. Here, for example, the supporting places 20 and 21 are formed. The
distance of the highest point of the underside 19 of the condenser 14 from the fibre-
guiding surface 16 of the delivery roller 2 defines the height s of the gap, which must
also be smaller than the thickness d of a single fibre 22.
The variation of the condenser 14 in Figure 6 shows a coating 25 on the underside
19. It is advantageous when the coating 25 is softer than the surface of the delivery
roller 2. The geometric shape of the coating in its new state is of less importance. A
possible form is denoted by the dot-dash lines 24. After the condenser 14 has been
assembled, the coating 24 is worn down over time, until the condenser 14 is
disposed and supported with its base material on the supporting places 20 and 21 on
the delivery roller 2. The areas of the underside 19, which lie higher and which would
normally form the gap, are still filled with coating material 25. The coating material 25
does not contribute to the support of the condenser 14, but rather ensures that the
gap height between the condensor 14 and the fibre-guiding surface 16 of the delivery
roller 2 approaches zero. The underside 19 of the condensor 14 is, for example, in
Figure 6 irregularly shaped. This is not absolutely necessary, the underside 19 could
just as well have one of the forms shown in Figures 3 to 5.
Figure 7 shows a view along the intersectional surface Ill-Ill of Figure 1. The gap 18
is limited here to the area of the guiding walls 15. The remaining area of the
underside 19 of the condensor 14 - crossways to the direction of motion A of the
fibre - forms a clearance 26 with the fibre-guiding surface 16 of the delivery roller 2,
whose height f measures several times the fibre thickness d. This embodiment is to
prevent broken- off fibre ends from settling into the outer area of the condensor.
WE CLAIM
1. A drafting unit (1) for spinning machines comprising a driven delivery
roller (2), to which two press rollers (3, 4) are arranged, said press rollers
(3, 4) forming together with the delivery roller (2) two successive nipping
lines (5, 6) between which the fibre strand (11) travels through a
condenser (14) supported on the delivery roller (2), having a tunnel-like
condensing zone (12), and comprising guiding walls (15) which at least
laterally taper in said condensing zone (12), the bottom of said
condensing zone (12) being formed by the surface (16) of the delivery
roller (2).
characterized in that
the condenser (14) contacts the surface (16) of the delivery roller (2) at
one or more supporting places (20, 21, 23) only and in that a gap (18)
between the guiding walls (15) of the condenser (14) and the surface (16)
of the delivery roller (2) in the non-contacting areas has a height (s)
which is smaller than the thickness (d) of a single fibre (22) of the fibre
strand (11) to be condensed.
2. A drafting unit as claimed in claim 1, wherein when fibres containing
cotton is processed, the gap (18) between the guiding walls (15) of the
condenser and the surface (16) of the delivery roller (2) is smaller than 7
micro meter along the entire length of the condenser (14), as seen in the
direction of motion (A) of the fibres.
3. A drafting unit as claimed in claim 1 or 2, wherein the condenser (14) is
provided with predetermined supporting places (20, 21, 23).
4. A drafting unit as claimed in one of claims 1 to 3, wherein the underside
(19) of the condenser (14) is provided with a coating (26) filing the gap
(18).
5. A drafting unit as claimed in one of claims 1 to 4, wherein the defined gap
(18) Is in the area of the guiding walls (15) of the condenser (14) only.
6. A drafting unit a claimed In claim 5, wherein the underside (19) of the
condenser (14) forms a clearance (26) with the fibre-gulding surface (16)
of the delivery roller (2) outside of the area between the guiding walls
(15), the height (f) of which clearance exceeds the thickness (d) of a
single fibre (22).


The invention relates to a drafting unit (1) for spinning machines comprising a driven delivery roller (2), to which two press rollers (3, 4) are arranged, said press rollers (3, 4) forming together with the delivery roller (2) two successive nipping lines (5, 6) between which the fibre strand (11) travels through a condenser (14) supported on the delivery roller(2), having a tunnel-like condensing zone (12), and comprising guiding walls (15) which at least laterally taper in said condensing zone (12), the bottom of said condensing zone (12) being formed by the surface (16) of the delivery roller (2), the condenser (14) contacts the surface (16) of the delivery roller (2) at one or more supporting places (20, 21, 23) only and in that a gap (18) between the guiding walls (15) of the condenser (14) and the surface (16) of the delivery roller (2) in the non- contacting areas has a height (s) which is smaller than the thickness (d) of a single fibre (22) of the fibre strand (11) to be condensed.

Documents:

760-KOL-2004-(09-11-201)-OTHERS PATENT DOCUMENTS.pdf

760-KOL-2004-FORM-27.pdf

760-kol-2004-granted-abstract.pdf

760-kol-2004-granted-assignment.pdf

760-kol-2004-granted-claims.pdf

760-kol-2004-granted-correspondence.pdf

760-kol-2004-granted-description (complete).pdf

760-kol-2004-granted-drawings.pdf

760-kol-2004-granted-examination report.pdf

760-kol-2004-granted-form 1.pdf

760-kol-2004-granted-form 18.pdf

760-kol-2004-granted-form 2.pdf

760-kol-2004-granted-form 3.pdf

760-kol-2004-granted-form 5.pdf

760-kol-2004-granted-pa.pdf

760-kol-2004-granted-reply to examination report.pdf

760-kol-2004-granted-specification.pdf


Patent Number 237493
Indian Patent Application Number 760/KOL/2004
PG Journal Number 52/2009
Publication Date 25-Dec-2009
Grant Date 23-Dec-2009
Date of Filing 25-Nov-2004
Name of Patentee MASCHINENFABRIK RIETER AG.
Applicant Address KLOSTERSTRASSE 20, WINTERTHUR, 8406 SCHWEIZ
Inventors:
# Inventor's Name Inventor's Address
1 BLANKENHORN PETER HEBBELSTRASSE 3, 89547 GERSTETTEN
PCT International Classification Number N/A
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 10356913.8 2003-12-02 Germany