Apparatus For Collecting Centrifugally Spun Filaments

Abstract

An apparatus for collecting centrifugally spun filaments from a rotating spinning device of a centrifugal melt spinning machine. The collecting apparatus includes at least one stationary air-jet, surrounding the rotating spinning device, a rotatable cylindrical collecting surface that is air-permeable, and a stationary cutter located between the rotating spinning device and the rotating collecting surface.

Description

BACKGROUND OF THE INVENTION

The demand for pitch filaments has increased in recent years due to the development of new methods for the production of carbon fibers from pitch filaments.

Many machines have been developed for the production of the filaments from materials such as polyesters and polyamides by means of centrifugal melt spinning. However, these conventional machines have not previously been successfully adapted to the production of pitch filaments suitable for use in the manufacturing of carbon fibers. Because the pitch filaments are relatively rigid and brittle, the collection of these pitch filaments requires special handling techniques not adequately provided for by the prior art apparatus. Conventional methods and apparatus have not been successful in producing pitch filaments of small diameter (several microns) and of relatively long length.

SUMMARY OF THE INVENTION

The present invention is a collecting apparatus designed to be used in combination with the spinning cylinder or spinning nozzle of a conventional centrifugal melt spinning machine. The apparatus of this invention includes at least one air-jet which surrounds the rotating spinning device and serves to blow the extruded filaments against a rotating collecting surface, which collecting surface is designed to allow easy passage of the air-stream therethrough and which catches and collects the pitch filaments. The device of the present invention also includes a stationary cutter located between the rotating spinning device and the rotating collecting surface which serves to cut the filaments into predetermined lengths. This apparatus is capable of producing pitch filament bundles of an unlimited continuous length with a minimum amount of breakage. The bundle is formed with a plurality of filaments, each cut to a given length, with the filaments arranged in a staggered relationship.

Accordingly, it is the object of the present invention to provide an apparatus for collecting brittle filaments with a minimum amount of breakage.

It is another object of this invention to collect pitch filaments of a predetermined length with a minimum amount of breakage.

It is yet another object of the present invention to provide an apparatus for the collection of brittle filaments into bundles and the cutting of the filaments into predetermined lengths, which operations are conducted with a minimum amount of breakage.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a longitudinal cross-sectional view taken along the center line of the apparatus of this invention;

FIG. 2 is a bottom plan view of the apparatus in FIG. 1;

FIG. 3 is a cross-sectional view taken along the line 3--3 of FIG. 2;

FIG. 4 is a view, partially in cross section, of the apparatus taken along line 4--4 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the preferred embodiments of the present invention, the rotating collecting surface is an "air comb" in the form of a plurality of closely spaced "T" shaped pins. The rotating air-comb is situated around the circumference of the rotating spinning device of a conventional centrifugal melt spinning machine. A stationary orifice air-jet or jets is provided around the periphery of the rotating spinning device, between the rotating spinning device and the rotating air-comb and serves to blow the extruded brittle filaments against the inner surface of the rotating air-comb. A cutter is also provided on a stationary surface, located at a point between the rotating spinning device and the rotating air comb.

In the practice of the present invention, the type of spinning device used is of little or no consequence. The present invention may be used with a wide variety of centrifugal melt spinning machines including rotary cylinder types and rotary nozzle types. For purposes of illustration, the collecting apparatus of the present invention is described in conjunction with a melt spinning machine of the rotary nozzle type.

With reference to FIG. 1, a rotatable spinning cylinder 10 is designed to receive molten pitch, which pitch collects in the central inner portion of a rotary bowl 12 which is rigidly attached to the lower portion of the rotatable spinning cylinder 10. The rotary bowl 12 is provided with a plurality of orifices or spinning nozzles 14. The molten pitch is forced through the nozzles 14 by centrifugal forces created by the rotation of the spinning cylinder 10.

Air from a pipe 18 directed outwardly through a ring-shaped orifice or stationary air jet 20 which surrounds the spinning cylinder 10. The uniform airstream so produced serves to carry or "draft" the pitch filaments along the lower surface of a stationary disc member 16 which surrounds the spinning cylinder 10. The extruded filaments are blown in whirls onto thecollecting surface of a rotary air comb 36. The air comb 36 forms a rotatable cylindrical collecting surface that is the collecting

The air comb 36 is supported by a rotary ring assembly, generally designated by the numeral 30. The rotary ring assembly 30 includes a gear member 34 which surrounds the stationary disc 16 and which has gear teeth on its internal surface. The ring shaped bracket member 32 is rigidly attached to the bottom surface of the gear member 34. The bracket member 32 has an inwardly extending flange or tongue 33. A roller assembly, generally designated by the numeral 22, includes ring shaped bracket member 24 which is stationary and extends around the circumference of the stationary dics 16, to which it is rigidly affixed. The bracket member 24 supports at least one roller member 26 which rotates about a pin 28. The roller member 26 is provided with a groove 27 which receives and supports the tongue 33 of the bracket member 32. The rotary air comb 36 is formed from a plurality of "T" shaped pins, spaced several centimeters apart and individually attached to the bracket member 32. The rotary comb serves to catch the extruded filaments while at the same time permits the easy passage therethrough of the airstream emanating from the ring shaped orifice 20.

The geared ring assembly 30 is driven by gear member 38 which is carried by a drive shaft 40 mounted in bearing members 42 which in turn are supported by drive shaft brackets 44. The drive shaft 40 carries a pulley member 46 which is shown as being driven by a "V" type belt 48.

A stationary cutter 50 is attached to the stationary disc 16 at its outer edge. FIG. 2 shows the position of the cutter 50 in relation to the rotary comb 36 and the stationary disc 16. FIGS. 3 and 4, which are cross-sectional views taken along lines 3--3 and 4--4, respectively, of FIG. 2, also show the cutter 50. A slide member 52 is mounted on the cutter 50 to receive the filament bundle. The filament bundle is continuously removed from the air comb 36 by means of an air nozzle 54 which serves to blow the collected filament bundle off of the air comb into the slide member 52.

In operation, the filaments centrifugally spun from the orifices 14 are blown in whirls along the under surface of the stationary disc 16 by means of the air stream emanating from the orifice 20 and then against the rotary comb 36 where they are collected in the form of a bundle of continuous length. The rotary comb 36 is rotated slowly in a direction which may be the same as or counter to the rotational direction of the rotary bowl 12. The air stream of nozzle 54 forces the filaments against the inner edge of the cutter 50 which serves to cut them into predetermined lengths. The cut filaments collect on the rotary air comb 36 until forced therefrom by the air stream from a second air jet or nozzle 54. The bundle 56 leaving the air comb 36 is removed by means of the slide member 52.

The air stream from the circular orifice 20 may be regulated at speeds which may vary from several hundred meters to several thousand meters per second. The length of the cut filaments will roughly correspond to the length of the circumference of the rotary comb 36. The filament bundle will be removed from the air comb 36 at a rate corresponding to the number of rotations per minute of the rotary comb.

The continuous bundles of pitch filaments leaving by means of the slide 52 are received by a conventional conveyor located beneath the slide and transported to subsequent processing steps such as sintering for the production of carbon fibers. Although the present invention has been described in connection with the manufacture of pitch filaments, it is understood that it is not limited to the manufacture of pitch filaments, but rather, will find utility in connection with the manufacture of any filamentary material of a brittle nature requiring special handling techniques. Various changes and modifications of the apparatus described above will become apparent to those skilled in the art, and thereofre, obvious and equivalent changes are intended to be included within the scope of the appended claims.

Claims

We claim:

1. An apparatus for collecting filaments extruded from a rotatable spinning device of a centrifugal melt spinning machine, said apparatus comprising:

1. a rotatable cylindrical collection surface, said cylindrical collection surface being air permeable and surrounding the rotatable spinning device;

2. at least one stationary air jet, positioned to convey the extruded filaments from the rotatable spinning device onto said cylindrical collection surface; and

3. a stationary cutter mounted between the rotatable spinning device and said rotatable cylindrical collecting surface, said cutter serving to cut the filaments to a predetermined length.

2. The apparatus of claim 1 wherein said rotatable cylindrical collecting surface is an air comb.

3. The apparatus of claim 1 additionally comprising a second air jet positioned to force the filaments off of said cylindrical collection surface.