FR2535740A1 - PROCESS FOR CENTRIFUGAL SPINNING OF FIBERS HAVING SPECIFIC PROPERTIES AND DEVICE FOR APPLYING SAID METHOD - Google Patents

Abstract

A.PROCESS FOR THE FINE CENTRIFUGAL SPINNING OF FIBERS HAVING PROPERTIES WHICH, BY RESULTING FROM THEIR INFLUENCES, CAUSE AN EXCESSIVE INCREASE IN THE AXIAL FORCE IN THE EXTRACTED WIRE. B. PROCESS CHARACTERIZED IN THAT THE INFLUENCE OF THE FRICTION FORCES ACTING ON THE WIRE 3 AT THE FIRST POINT OF CONTACT ON THE EXTRACTION PATH 4, 6 AFTER THE COLLECTION SURFACE OF THE SPINNING ROTOR. C. THE INVENTION IS APPLICABLE TO THE FINE SPINNING OF PARTICULAR TEXTILE FIBERS BY THE CENTRIFUGAL PROCESS.

Description

Process for the centrifugal spinning of fibers having

  specific properties and device for the application

this process ".

  The invention relates to the centrifugal spinning of fibers having properties which do not allow

  perform centrifugal spinning in yarns of acceptable quality

  current arrangements, as the result of the

  the influence of these properties increases by

  excessive axial force in the yarn extracted from the spinning rotor, so that these fibers are clearly distinguishable, especially cotton.

  In particular, as "specific properties", the coef-

  friction ficients (especially dynamic) of the surface

  this fibers, as well as the adhesion of the thread on others-

  surfaces, the deformability of the cross-section of the wire, including the decrease of the hardness of its surface as well as the resistance to the bending of the wire and the importance

of its specific surface.

  In particular, the fibers which have to be treated like cotton are provided, already

  during their manufacture, a film of prep -

  ration of the surface (brightening) which gives them, without

  other primer or adaptation of the properties of the

  face conferring shaping ability on those who will perform It is not common in technology

  of cotton, to prepare the surface and to re-prepare it,

  this is the case in wool technology It is therefore obvious that the properties mentioned relate to the total complex: fibers / film of prepa-

  The surface of the surface shows that the fibers

  from the same macromolecular (and even morphologically similar) substances, may differ very significantly in their specific properties.

  indicated precisely because of differences in

surface loans.

  The invention solves the problem of spinning

  Fine centrifugal fiber with specific properties

  by lowering the axial force in excess of the wire

  extracted up to a determined optimal value, in

  both the point of the first contact of the wire, on its

  extraction course after the rotor collecting surface,

  when entering the thread into what is called enton-

  wire extraction black, that is to say by adjusting the active input surface of the wire extraction funnel. Known centrifugal spinning processes

  to date have been successfully applied in the industrial

  very successful with natural fibers

  cotton (initial stage of wool processing), chemical fibers (rayon-viscose) and

  synthetic fibers (polyester fibers), and possibly

  The resultant of the influence of the specific properties of the chemical fibers, as well as the synthetic fibers, on the friction and consequently on the axial force of the wire obtained by the spinning, and extracted from the rotor on the metal surface,

  however, does not differ significantly from that of cotton.

  We have now achieved, for centrifugal spinning

  these fibers, to an optimum and the efforts of perfection-

  especially apply to the adaptation of properties

surface of the new fibers.

  The current evolution of funnels of ex-

  pulling yarn for fibers spun up to

  the centrifugal process, which is not too distinct from cotton, is directed by the tendency to establish, on the funnel, friction conditions such that it becomes possible to obtain better control, and localization. determined the wire in the return path of the funnel to the surface of

  rotor collection This trend requires rubbing

  the active entrance surface of the funnel, and its limiting factor lies in the axial resistance of the wire

  patents have hitherto made use of different combinations of

  Funnel surface surfaces, smooth and rough, (eg, change during a revolution of the rotor between smooth segments and rough segments on the funnel), radial forges as well as

  concentric, on the active input surface of the en-

funnel and others.

  These solutions can not be used

  centrifugal spinning of fine wire with specific properties, since the coefficient of friction on the smooth active active inlet surfaces of the funnel is already so high that it is not possible to increase it further by example by means

a rougher segment.

  Friction is the result of the interaction of two surfaces, the one that is rubbed and the one that rubs Current technical practice has a relatively limited possibility to compensate for the effect of too many coefficients of friction of many fibers by reducing the coefficient of

  friction of the active surfaces of the extrac-

  The possibilities of a similar operation

  with fibers, that is, the reduction of

  Also, fibers using a preparation applied to the fiber surface during manufacture are also limited.

  In known devices up to now

  for centrifugal spinning, which contain spinning stations comprising a rotor and an extraction funnel, it is not envisaged to adapt the production of the extraction funnel, in principle, to the results of the influence. Specific properties mentioned of specified fibers The path and type of contact with a given return angle of the wire to be extracted, which are determined by the radius of curvature "r" (see the attached drawing) of the entrance surface of the funnel with which the wire makes contact, are

  too unsuited to spinning fibers with

  specific properties It is certainly known that

  the radius of curvature of the active entrance surface leads to a decrease in the axial force of the wire to be extracted, however to a degree that is not very important, so that one can not take advantage of

  of this provision, nor to resort systematically to

  only to compensate for undesirable results of the influence of specific properties on friction on the active entrance surface of the funnel and thus on the excessive increase of the axial force

in the wire to extract.

  An excessive increase in the axial force has the following consequences: a decrease in productivity (the axial force,

  proportional to the square of the speed of rotation-

  of the rotor makes it necessary to reduce this speed of rotation of the rotor, and consequently causes a decrease in the speed of extraction of the wire, an excessive abrasion of the preparation (brightening) of the surface of the fibers, or even an abrasion of the mass itself of the fiber and consequently an increase in the formation of dust, this dust being sucked by the rotor, which requires greater

  frequency of rotor cleaning, but especially in

  reduces the quality of the wire, increases the number of wire breaks, which coincides with a greater probability of breakage

  wire under the effect of a voltage exceeding the

wire.

  The disadvantages indicated above are eliminated by the centrifugal spinning process according to the invention for fibers having properties which cause an excessive increase in the axial force because of the results of their influence on the wire to be extracted; based on the fact that the influence of the friction forces acting on the wire can

  be reduced on the input active surface of the

  wire extraction funnel, by shortening the

  course of contact with the wire to be extracted, so that

  an optimum axial force of the yarn is obtained.

  re in the section following the exit of the funnel.

  This force, measured after the input active surface of the penetrant, and also after the exit surface, (in the case where the funnel has an active exit surface) does not exceed 2.5 times the axial force F which is established on the rotor and which is given by the following equation: F = 5, 45 10 12 R 2 n in which F = the axial force of the wire to be extracted in the section which lies between the collecting surface of the

  spinning rotor and the entrance into the funnel of ex-

  tensile force, measured in m N / tex, R = the radius of the spinning rotor in mm,

  n = the speed of rotation of the spinning rotor per minute.

  Shortening the course with

  tact of the yarn on the funnel entrance active surface is obtained by lowering the height of the funnel head portion having a given radius of curvature,

  while it is not possible on this device,

  kill in an acceptable way, centrifugal wire spinning

  end with fibers having specific properties

  By decreasing the height of the funnel head portion, in addition to shortening the path with wire contact on the input active surface of the originally unsuitable extraction funnel, an active surface is further formed. a quality

  new, which is formed by the entrance edge and the res-

  te of the initial input active area.

  As indicated, and by means of an easy-to-use device for executing it, it is possible to compensate the resultant of the influence of the specific properties, different for different fibers, on their friction in the critical part of the path of travel. extraction, and on the excess of axial force of the wire which one must extract which would be the consequence, with, for final effect, obtaining a wire of higher quality, which can be spun end with remarkable

productivity characteristics.

  The single appended figure represents the active outlet surface of the extraction funnel as well as the principle of the invention which is based on the modification of the contact of the wire which must be extracted from the

  spinning rotor with the input active surface of the en-

TONNOIR.

  The extraction funnel 1, the dia-

  inner meter is "D" at the orifice is shown in longitudinal section along a plane passing through the axis

s 2535740.

  2 of the funnel, which is at the same time the axis of rotation of the spinning rotor The wire 3 is removed from the collecting surface of the spinning rotor by passing over the circular edge 4, then by the surface active input 5 of the funnel, which is determined by the edge 4 and the last contact point 6 of the input active surface, which has a radius of curvature "r" The edge 4 is a line of circular section of the surface which is formed by the rotation of a quadrant having the radius "r" on the axis 2 at a distance D (rotational surface which

  forms the input active surface 5) as well as a defined plane

  ending the height "h" of the head part of the

  funnel, this plane extending perpendicular to the axis 2. The path with contact is shortened,

  according to the principle of the invention, for a given value.

  born "r", by reducing the height of the funnel head portion by a value (Hh), if it is compared with the contact path on the funnel when the height of the head portion is H, the use of this height giving the wire to extract an axial force

  excessive After the input active surface 5 of the

  after the point 6, the wire is pulled by the usual extraction and winding device, either directly or by passing first on a surface

  funnel output, which is formed for example by

  by a ceramic ring (made of sintered corundum), a bent tube with variable angular values and the like, and then in the extraction device. The active exit surface, like the winding device,

  are not shown in the figure.

  In the figure, are indicated by a

  line interrupted the parts of the funnel that are -

  not suitable for centrifugal spinning of fine numbers, -

  fibers with specific properties (specific

  a funnel where the head part has a height H, from which it is the most

  simple to form a well-adapted funnel with a high

"h" of the leading part.

  Examples of a concrete embodiment are given here in the form of a summary in the following table. The decisive criteria of the axial force in the wire to be extracted (in the form of mean values of the graphical records at the same intervals time of threading) in common with the characteristics of the quality of the spun yarn, which

  corresponds to the funnel initially used (enton-

  Black standard -S) or the new (N), which is obtained by grinding the S according to the invention It appears a consequence sufficiently representative of the results of the fine spinning of a fiber sample in the same climatic conditions The ratios between the values

  the axial force and the quality of the wire are entirely

  preserved even for one type of fiber quite

  different, as it appears from the examination of a large.

  number of series which are similar to those given. Indications on the type of fiber are in

  consequently superfluous in the example given.

  The result of the use of the funnel S is valid

  only for the beginning of the spinning, then he

  With a properly optimized N funnel (eg

  ples 2 and 4), the result does not change with time. BD 200 S centrifugal spinning machine

the end -

  Rotor Radius (mm) 27 Spinning Drill Bit Reached Twice, 3.3 ktex Speed of Combustion Roller (Min 1) 6,000 Wire-Finish Finesse (tex) 35.5

2535740.

  Torsion Rotor Rotation Speed -1 (Min) Wire Extraction Speed (m / min -1) Funnel Used (NI Example)

Radius of curvature r of the sur-

active input face (mm)

Inner diameter of the original

  fice D (mm) Height of the head part H or h (mm) Active input surface Active output area Axial force (m N / tex) of the yarn extracted:

after the release of the

  active face F before the active input surface F o ratio F / Fo Quality of the yarn obtained: irregularity USTER (CV '%) number of thin parts number of thick parts number of nopps

46,250 51,200

74.6

S / 1 N / 2 5/3

82.6

N / 4 N / 5

4 4 4 4

2 2 2 2

  H 3.9 h 2.4 H 3.9 h 3.1 smooth, hard chrome ring sintered corundum h 2.4

18 50 31 23

8.5 8.5 10.4 10.4 10.4

4.7 2.1 4.9 3 2.2

19.5 16.2

19.6 17.3

468,202

620,310

428 '150

2535740.

Claims (1)

CLAIMS) A process for the fine spinning of fibers having properties which, by the result of their influences, cause an excessive increase of the axial force in the yarn to be extracted, characterized in that the influence of the friction forces acting on the wire (3) at the first point of contact on the extraction path (4, 6), after the collecting surface of the spinning rotor, that is to say on the input active surface of the extraction funnel by shortening the path with contact of the wire to be extracted in the section that follows the exit of the funnel and lowering the height (h) of the inlet of the funnel (4).   20) A method according to claim 1, characterized in that one obtains an optimum axial traction force of this wire, which does not exceed 2.5 times the axial force given by the equation FO = 5.45 10 12 R 2 n equation in which: F = the axial force of the wire to be extracted in the section which lies between the collecting surface of the rotor of   spinning and entering the extraction funnel, measuring   in m N / tex, R = the radius of the spinning rotor in mm, n = the speed of rotation of the spinning rotor per minute. ) Installation for the application of the   method according to one of claims 1 and 2, which   contains a spinning station with a rotor and an enton-   extracting black having an active surface,   characterized in that the active surface (1) of the funnel is formed by the inlet edge (4) with the section determined by this edge and the last point (6) of contact of the wire on this active surface, and determining the desired shortening of the course 2535740.   h with wire contact by a choice of the height of the head portion e of the funnel (h) for a radius of curvature r given.