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Dec. 24, 1946.
A. M. SAW
2,413,073"
STRETCHING ROLLS
Filed July 26, 1945
INVEN TOR.
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Patented Dec. 24, 1946
UNITED \‘STATESQPATENT. OFFICE '
STRETCHING ROLLS
Arthur M. Saum, Wilmington, Dei., assignor to
E. I. du Pont de Nemours & Company, Wil
mlngton, Del., a corporation of Delaware
'
Application J nly 26, 1945, Serial No. 607,234
4 Claims.
'
1
(c1. 28-713)
n
This invention relates to the manufacture of
lation with the feed roll in a manner .hereinaiter
fully described, whereby yarn passed over and.
between the feed and pinch rolls will cause the
arti?cial ?laments, yarns, threads, ribbons, etc.,
and more particularly to an improved arrange
ment to prevent slippage of arti?cial ?laments,
yarns, threads, ribbons and ‘the like under ten-'
sion on positively driven advancing rolls.
.
Heretofore, much diiiiculty has been experi
enced in the stretching or drawing of yarns and
pinch roll to be iorced against the teed roll and
0
pinch the yarn therebetween with a force sum
cient to prevent slippage oi’ the yarn on the
feed
roll.
,
.
'
-
Referring now to the drawing wherein like
the like by means of two or more sets of positively
reference numerals designate like parts. refer
driven rolls turning at different peripheral speeds ' 10 ence numeral i (Fig. 1) indicates a freely rotat
due to inconstant slippage of the yarn thereon.
able pinch roll l, aligned parallel to the usual
Various arrangements have been proposed ‘and
positively driven feed roll 2, and mounted for
used, such asa plurality of turns of the yarn
swing on one end of a swing arm 3 which is piv
about the advancing roll and about a suitable
oted at the opposite end to the frame of the spin
auxiliary roller for displacing the yarn in its
ning machine or any other suitable support. The‘
several passes about the advancing roll, pressure
swing arm and attached pinch roll may be dis
' rolls bearing on the ‘yarn passing around the yarn
posed at any point about the feed roll so long as
advancing roll, etc. These prior arrangements
the pull on the yarn passing over and between
' work quite satisfactorily when the tension diiier
the rolls will tend to done the rolls into con
ential between the oncoming and o?going yarn 20 tact, and the length of‘ the swing arm and the
is not too great. However, where the tension
radius of the pinch roll are such that the pinch
di?erences are large, yarn slippage on the ad- '
roll cannot be swung past the feed roll. It is
vanclng roll occurs and the stretching ratio be
further required that'the pivot point of the-swing
comes variable. This
culty is especially acute
in the drawing of heavy denier yarns or ?la 25 arm be so located that the obtuse angle a formed
by the intersection of the straight line passing
ments of nylon which require an unusually large
through and connecting the ‘centers of the two
force to attenuate the structure to approximately
four times its original length. '
rolls andthe straight line passing through and
connecting the center of the pinch roll and pivot
It is, therefore, an object of this invention to
provide an improved yarn advancing roll arrange 30 point of the swing arm is within the range of
from 165° to just short of 180". In the arrange
ment that is simple to make and install, easily
“strung up,” and, in operation, capable or pre
venting slippage oi the yarn on the advancing
roll even though the tensions on the yarn thereto
and therefrom di?er widely. Other objects will
be apparent from the description that follows
which is to be read in connection with the ac
companying drawing wherein:
Figure l is a diagrammatic illustration of one
arrangement of yarn advancing rolls embog
the principles of my invention;
Figure 2 is a diagrammatic representation of
an alternate arrangement of rolls according to
my invention; and
ment shown in Fig. i, the distance between the
axes of rotation of the swing arm 3 and of the
feed roll 2 is slightly less than the sum of the
‘length'of the swing arm (distance between the
35
axis of rotaticnof the swing arm and axis of
rotation of roll 3) and the radii of the pinch
roll i and the feed roll 2. in order that the pinch
roll cannot quite swing past the feed roll. More
40 over, the center points oi’ the two rolls and the
pivot point or theswing arm are almost in a
straight line, i. e., the angle a is almost 180".
‘With this arrangement a force which tends to
push the pinch roll pat the feed roll develops a
Figure 3 illustrates a med form of the 45 muchlgreater compressive force between the two
pinch roll.
‘
' roll surfaces than can be obtained if the pinch
These objects are accomplished by my inven- ' ’ vroll is supported in vertical guideways directly
over the feed roll or if‘the swing
of a swing?
tion'. which, brie. stated,‘ comprises associating
with the usual driven iced or yarn advancing
ably mounted‘ pinch roll is so pivoted that the
roll of a conventional system of rolls arranged 50 angle or isless, than about 165°. When the yarn
for the stretching of arti?cial yarn and the like, ‘ strung around the rolls disposed in accordance
with the principles of this invention and in such
a freely rotatable, swinghbly mounted roll (here
a way that the tension on the yarn as it is with
inafter termed f‘pinchv roll") having its axis of
drawn tends to pull, the pinch roll past the iced
rotation parallel to the axis of rotation of the
mil, and further disposed in contacting re 55 roll, then the pinching action between the rolls
/
‘ 2,418,078'
3
.
.
t
4
‘ grips the yarn more ?rmly as the yarn tension
ful, too, to improve twist uniformity in difiicultly
increases and slippage cannot occur.
In the modi?cation shown in Fig. 2, the dis
tance between the axes of rotation of the swing
handled structures such as tire cord.
By means of this invention, heavy denier yarns
arm and of the feed roll is slightly more than
the length of the swing arm minus the radii of
the pinch roll and the feed roll and the obtuse
angle a is more than 165°. Here, as in the pre
and ?laments of nylon have been produced with
more uniform physical properties than has been
possible heretofore, by virtue of the elimination
vof yarn or ?lament slippage on the draw rolls.
Furthermore, the arrangement described can be
viously described arrangement (Fig.1), the yarn
very quickly “strung up" and is easily restrung
as it is withdrawn from the pinch roll tends to 10
whenever a break occurs.
‘
‘
As many apparently different embodiments c
this invention can be made without departing
feed roll.
from the spirit and scope thereof, it is to be un
The yarn must be withdrawn in a direction
to cause the pinch roll to be forced against the 1 derstood that said invention is not to be re
advancing roll, and the surfaces of the two rolls 15 stricted save as de?ned by the appended claims.
I claim:
'
should in part at least be such that the coe?i~
1. In combination, a driven roll positively
cient of friction between them is relatively high.
driven about a ?xed axis, a pinch roll in contact
Preferably the ‘feed roll is a steel-surfaced roll
with said driven roll ‘and freely rotatable on an
while the pinch roll is rubber-, cork- or leather
covered.v While the feed roll could be covered 20 axis parallel to the ?xedaxis of the driven roll,
said pinch roll being mounted on the free end of
with rubber, or leather, or cork, and the pinch
a swing arm which is pivoted at the opposite end,
_ roll steel-surfaced, a frictional loss will occur re
the pivot point of said swing arm being ?xed and
' ducing the resistance to slippage of the yarn on
so located that the obtuse angle formed by the
these rolls since the relatively large arc of con
tact of the yarn with the pinch roll under high 26 straight line connecting the centers of the two
rolls in operative contacting position and the
tension becomes less effective than if the two
straight line connecting the center of the pinch
rolls were surfaced as ?rst described. A satis
roll and the pivot point of said arm is within the
factory pinch action between steel-surfaced rolls
can be obtained by providing one of the rolls with . range of from 165° to Just short of 180°.
2. In apparatus for stretching stretchable ma
end bands 4 or i as shown in Fig. 3. These bands 30
terial wherein the material is stretched between
are of a diameter slightly larger than that of
positively driven rolls, the improvement which
the roll and are constructed of rubber or like
comprises in combination with the ?rst of said
resilient material having a high coe?lcient of
driven rolls‘ positively driven about a ?xed axis.
friction.
‘a swing arm pivoted at one end. a pinch roll
The feed roll assembly above described is es
pull the pinch roll past, and hence against,_the
.‘pecially useful in feeding large denier undrawn
mounted on the free end of said arm and free
ly rotatable about an axis parallel to said ?xed
axis, said pinch roll being further positioned so
that it swings on said arm into contact with.
stantially higher peripheral speed to stretch the
yarn or ?laments approximately four times their 40 said ?rst driven roll, and the pivot point of said
arm being ?xed and so located that the obtuse
original length. As disclosed in U. 8. Patent No.
angle formed by the intersection of a straight
2,289,232 to D. 1"..Babcock, a draw ‘Din is pref
erably positioned between two sets of rolls. Even ‘ line passing through and connecting the axes of
the ?rst driven roll and the pinch roll in operative
though the force required to stretch the yarn or
- ?lament to four times its length is as much as 'contacting position and a straight line passing
through and connecting the axis of the pinch‘ roll
two or three pounds vor more, experience has
and the pivot point of the arm is within the range
shown that no slippage results on the feed roll
of ‘from 165° to Just short of 180°, whereby ma
assembly when constructed as above described
terial passing between the ?rst driven and pinch
with the pinch roll rubber-covered and the driven
feed roll steel-surfaced, whereas prior methods 50 rolls and drawn o? the pinch roll under tension
in a direction effective to urge the pinch roll into
would involve slippage if the drawing tension
contact with the ?rst driven roll is subjected to
were greater than about 0.5 pound.
nylon yarn or a large denier undrawn nylon ?la
ment to another pair of rolls turning at sub
While this invention is especially suited to the
drawing of very heavy denier nylon yarns such
' as 1000 denier or more, and large diameter nylon 55
?laments such as may be used for bristles, horse
hair substitutes. tennis racket strings, musical in
strument strings, ?sh line leaders, surgical su
a pinch pressure suf?cient to prevent slippage of
said material on said ?rst driven roll.
v
3. Apparatus according to claim 2 wherein
either one of the two contacting rolls is surfaced
with a material having a coe?lcient of friction
which is high relative to the cce?lcient of fric
tion of the surface of the other roll.
4. Apparatus according to claim 1 wherein the
0.002 to 0.06 inch in diameter, the invention may 60
?rst driven roll is steel-surfaced and the pinch
also be used in connection with the feeding .or
roll is surfaced with a material having a sub
advancing of yarn tow, or ?laments of any char
tures, screening, etc., and ranging in size from
acter where a; very high tension differential exists
in the yarn in going on and coming 01! the ad
vancing roll arrangement. This invention-is use
stantially higher coefficient of friction.
ARTHUR M. SAUM.
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