Device for guiding a sliver into a can coiler

A web of fibers delivered from a drawing machine is assembled into a sliver which passes into a guide duct, then passes between takeup rollers into a can coiler. Downwardly inclined air-escape holes are pierced in the wall of the guide duct in order to discharge the air entrained by the sliver. There is consequently no swelling of the sliver on the delivery side of the takeup rollers and no pressure rise towards the guide duct inlet, thereby facilitating the introduction of the web into the duct.

The rollers 1 and 2 represent the last stage of the drawing system of a 
machine. The fibers are delivered in the form of a web 3 which, in the 
case of a high-draft machine, is extremely tenuous and fragile. This web 
is applied against a deflector 4 and has to be condensed into a sliver in 
order to pass through an orifice 5 into a duct 6. Said duct guides the 
sliver M towards the cone-shaped throttling exit 7 which terminates in an 
opening 8 for the passage of the condensed sliver 9. After delivery from 
the guide duct, said condensed sliver passes between the drafting wheels 
10 formed by the pair of cylinders 10a, 10b which have the design function 
of takeup rollers for transferring the condensed sliver to a conventional 
can coiler as shown diagrammatically in the figure and designated by the 
reference 13. 
When the drawing machine rotates at its production speed, the web 3 which 
passes through the orifice 5 of the deflector 4 entrains the air contained 
within the interstices of the fibers along the guide duct 6 up to the 
level at which the throttled section 11 produces a pressure rise P and 
very high turbulence, thereby having the effect at the same time of 
setting up a resistance to the web 3 and to the sliver as this latter 
arrives from the deflector 4. 
In accordance with the invention, there are formed in the wall 14 of the 
guide duct 6 one or a number of air-escape holes 12 which open to the 
surrounding atmosphere. These holes permit discharge of air (in the 
direction of the arrow F) while preventing any pressure rise P within the 
guide duct 6 and disintegration of the web 3 at the level of the orifice 5 
of the deflector 4. 
In the case illustrated in the FIGURE in which the guide duct 6 terminates 
in a throttled zone 7, the air-escape holes 12 are advantageously formed 
in close proximity to said throttled zone in which turbulent airflow is at 
a maximum. 
In the event that the guide duct 6 has a substantially constant 
cross-section over its entire length and has a tapered end portion which 
is adapted to fit in position between the takeup rollers or else in the 
event that the guide duct 6 has a progressively decreasing cross-section, 
the air-escape holes 12 can be formed at any desired point of the flow 
path in the guide duct 6. 
Since the pressure of air contained within the sliver has a tendency to 
rise as indicated by the arrow P in the FIGURE, it is an advantage to 
ensure that the hole or holes 12 are inclined from the exterior towards 
the interior of the guide duct in the direction of travel of the sliver M. 
The device in accordance with the invention has a further advantage in that 
it prevents swelling of the condensed sliver 9 as this latter is delivered 
by the two takeup rollers 10a and 10b, with the result that a greater 
length of sliver can be coiled into the same can. 
The air-escape holes 12 which are inclined in the direction of travel of 
the sliver (as shown in the FIGURE) are particularly advantageous in the 
case of a high-speed drawing machine. It has in fact been observed that, 
if an air-escape hole 12 is oriented at right angles to the direction of 
travel of the sliver, the diameter of said hole must be limited in order 
to prevent the fibers from catching on the periphery of the hole. 
Air-escape holes which are thus limited to a small diameter are 
consequently liable to be clogged with fibers entrained by the air which 
is intended to escape through the holes. 
On the contrary, an inclined hole which slopes downwards in the direction 
of travel of the sliver does not offer any resistance to the flow of 
fibers since there is no sharp edge located at right angles to the 
direction of flow. By virtue of this inclination, the diameter of the 
air-escape holes can be increased without any attendant danger of catching 
of the fibers or of clogging of the hole with fibers. 
The preferred angle of slope is in the vicinity of 60.degree. with respect 
to the axis of travel of the sliver as shown in the FIGURE but this angle 
may be reduced to the minimum limit at which machining operations still 
remain possible.