US2598000A

US2598000A - Multiple stage tow drying

Info

Publication number: US2598000A
Application number: US165625A
Authority: US
Inventors: Wallace A Knopp; Thomas L Nash
Original assignee: American Viscose Corp
Current assignee: Akzo Nobel UK PLC
Priority date: 1950-06-02
Filing date: 1950-06-02
Publication date: 1952-05-27
Anticipated expiration: 1969-05-27

Description

May 27, 1952 w. A. KNOPP ETAL MULTIPLE STAGE TOW DRYING 2 SHEETSSHEET 1 Filed June 2, 1950 INVENTORS. WALLACE A. KNOPP THOMAS L. NASH ATTQRNE y 1952 w. A. KNOPP ET AL 2,598,000

MULTIPLE STAGE TOW DRYING Filed June 2, 1950 2 SHEETSSHEET 2 INVENTORS. WALLACE A. KNOFP THOMAS L. NASH A rr omvg Patented May 27, 1952 UNITED STATES PATENT OFFICE MULTIPLE STAGE 'row DRYING Application June 2, 1950, Serial No. 165,625

16 Claims.

The present invention relates to the drying of continuous filamentary bundles particularly-the bulkier types of strands such as sliver, roving and tow. For illustrative purposes, the invention is hereinafter described with respect to the drying of rayon materials. A conventional method of drying .rayon tow prior to its being cut into staple fiber involves distributing the tow on a belt-like conveyor by laying the tow in folds which extend transversely of the conveyor. Deposition of the tow is accomplished by a feeder which reciprocates transversely of the conveyor in a manner to lay the tow in a flat ribbon in a pattern wherein each succeeding course of tow overlaps the preceeding one to give a shingle eifect. This mode of deposition is such as to produce a blanket of several tow layers in thickness due the overlapping of the successive layers. The exposed surface and the edges dry more rapidly than the overlapped sections. Itis thus diiiicult to direct a drying medium through the blanket of tow in such a manner as to secure uniform passage of air through adjacent sections of the blanket and to avoid the production of wet spots in the material discharged from a dryer.

It is an object of the present invention to provide a continuous method and an apparatus for uniformly drying large strands of filamentary material. It is also an object to dry material more rapid and to increase the drying capacity of space occupied by equipment for drying the material. Other objects, features and advantages of the invention will become obvious from the following description of the invention and the drawing relating thereto in which;"

Fig. l is an elevation view of apparatus for carrying out the method of the invention;

Fig. 2 is a pictorial view of apparatus for distributing a plurality of continuous filamentary bundles; and

Fig. 3 is a pictorial view of another apparatus for distributing the bundles.

According to the invention, a bulky filamentary bundle is carried on a continuously moving conveyor of a dryer in a sinuous wave pattern the amplitude of which is preferably nearly the minimum that will produce the wavy pattern and yet cause the bundle to be substantially self.- supporting on an edge thereof. The bundle is lifted from the conveyor at one or more points spaced longitudinally along its path to eliminate the pattern of deposition of the advancing bundle, and redistributed onto theconveyor into a reformed sinuous pattern by a reciprocating feed device.

Fig. 1 illustrates a drying apparatus comprising a feed section 6, drying sections 1, 8 and 8, and a discharge section [0. A conveyor l2 advances progressively through all sections from the feed section. A tow 14 of the type comprising several thousand filaments, such as used to produce staple fiber, is passed into a pendulum type oscillating feed device l5 from a pair of nip rolls I6 positioned exteriorly of the dryer. The tow distributing device l5 may be the pendulum type such as that illustrated in Fig. 2 or anyone of other well-known reciprocating feed devices. A reciprocating nip roll distributing device such as that illustrated in Fig. 3 may readily be substituted for that of Fig. 2. Either apparatus of Figs. 2' and 3 may be used to pass the tow to the conveyor in the feed section 6 or to lift the tow from the conveyor for redistribution thereupon in the drying sections 8 and 9.

In the drying apparatus illustrated, three independent drying sections are provided in which the temperature and the humidity of the air passed into each section may be independently controlled, if desired. However, so far as the present invention is concerned, the partitions which separate section 8 from sections 1 and 9 may be removed to permit operation of the dryer as a single compartment drying apparatus. The advantages of the present invention accrue primarily from the breaking up and reforming of the pattern of tow deposition on the conveyor E2. The tow in passing progressively through the various sections passes under bailles 20 which are hinged to stationary baffles 2| to prevent the passing of drying medium from one section to the other. On the underside of the portion of the conveyor which carries the tow, other movable baflles 23 are hinged to stationary baflles or walls 24 which define the various sections of the dryer having ports 25a, 26a and 2101.. If heated air is passed into the dryer through ducts 25, 2B and 21 connected to the dryer through the ceilings of the drying section, the air will flow downward through the conveyor and the tow material carried thereupon and thence out through the ports 25a, 26a and 21a. When desired, the dryer may be operated with these ports as the inlets for the gaseous heating medium and the ports 25, 2S and 21 as the outlets.

The equipment illustrated in Fig. 1 for lifting the tow from the conveyor and reforming it in a newly developed sinuous or zig-zag'patternare devices such as the one shown in Fig. 3 comprising one or more pairs of nip rolls supported on a frame which is reciprocable in a direction trans versely to the direction of movement of the conveyor I2. In the device illustrated, two separate tow-handling units 50 and 5| are illustrated as supported on a single carriage 52. However, the length of the carriage may be readily extended and more of such units may be mounted thereon when the conveyor and dryer capacity is such as to warrant the handling of a greater number of tows on a single conveyor.

Referring to Fig. 2, apparatus is illustrated in which two tows 5!! and 31 are being lifted from the conveyor l2 and passed through a device such as device 56 of Fig. 1 comprising two pairs of nip rolls 33 and 34 which are driven from the motor 35 and gear reduction unit 35. Each tow passes from its respective nip rolls into a pendulum-

type distributor

38 or 38, and then into a feed hopper 4B. The distributors are oscillated transversely of the conveyor l2 with respect to their respective stationary pivots 4| Oscillation of the distributors may be effected by means such as a reverse screw shaft 43 extending from the gear reduction unit 36 and acting on a pawl Ma mounted in a collar &4. The collar is linked to a crank pin 46 extending from the distributor 39 by a link 45. A link 48 transmits the drive from crank pin 53 to crank pin 49 of the distributor 38.

Fig. 3 illustrates apparatus such as

devices

28 or 29 of Fig. 1 comprising two pairs of nip rolls 5!! and 5| mounted on a single carriage 52. Each pair of rolls is positively driven from a shaft 55 having pulleys 54a and 5% in drive connection with pulleys of the rolls by belts 55 and 56. The

carriage 52 and the assembly carried thereon 1 may reciprocate in a direction transversely of the belt [2 on rails 58 and 59. Recip-rocation of the carriage may be obtained by an arrangement such as a crank pin (if of a bevel gear 52, the

pin describing a circular orbit while extending through the end of a connecting rod 64. The connecting rod 64 is pivotably secured to a stationary portion 65 of the dryer. A motor 61 in drive connection with a gear reduction unit 68 constitutes the driving means for rotating the rolls and reciprocating the carriage. A drive shaft 10 extending from the gear reduction unit 68 supports a drive pulley 'H connected by a belt 13 with a pulley ill on the shaft 56, and also supports a bevel gear '12 in mesh with the gear 62 of the reciprocal drive system of the carriage 52. A feed hopper is supported from the rail 58 on brackets 16 and Ti to receive the tows as they are discharged from the pairs of rolls 5!! and 5!.

In accordance with the present invention, the

tow distributing devices

16, 28 and 29 are adjusted to deposit the tow in the conveyor [2 in a sinuous but narrow pattern. The development of the pattern formation is promoted by collection of a few folds within a hopper 40 or 15. The hoppers receive and stack the folds of the tow one on top of the other with the flat sides of the folds generally horizontal. The hopper is curved or slanted away from the vertical (proceeding in a downward direction) as illustrated to reorient folds as they descend within the hopper so that they will be less horizontal as they are discharged onto the conveyor and will readily assume the desired position on the conveyor in which the flat sides are generally vertical. In this manner, the distribution of the tows upon the conveyor are pare-arranged to a large extent within the hoppers. If desired, inclined plates or baffles extending transversely of the conveyor may be substituted as simpler but less protective strucand 42.

ture in place of the hoppers illustrated in the figures.

The ambits of reciprocation of the distributing devices and the lateral scope of the conveyor in which the tow is deposited are preferably limited to the extent that the transverse sections of the tow are self-supporting between bends at opposite sides of the section of the conveyor which receives a single tow, i. e. the transverse sections tend to stand on edge and do not to a substantial degree lay over against an adjacent section to overlap a portion thereof. As the tow is flat tened into a somewhat ribbon-like shape after passing between the nip rolls of devices it, 28 or 29, it bends across the flatter direction of the tow when deposited within the feed hopper or on the conveyor, and stands or supports itself on the edge of the ribbon-like mass, i. c. if the transversely extending sections of the tow between the bends are short. A slight sagging in the sections allows them to spread in a direction normal to their flatter surface; such spreading is maximum in such sections midway between ad j'acent bends. As the drying medium moves through the dryer in a direction normal to the plane of the conveyor, this spreading effect is beneficial in that it permits more efiicient covering of the conveyor and therefore greater contact of the drying medium with the fibrous material of the tows.

The outer filaments of a tow are substantially dried by the time they pass into the first redistributing device spaced from the tow-receiving end of the dryer. A redistributing device, such as 28 or 29, then picks up the tow and subjects it to a kneading action between the nip rolls. Such working results in the filaments being rearranged within the tow relative to its surface. The tow is then discharged from the device and redistributed along the conveyor 12 in a zig-zag or sinuous pattern with the bends of the pattern occurring at points along the tow which are different than the points of bending in the tow before it entered the device. To secure this result, the various devices I6, 28 and 29 may be operated at varying reciprocation frequencies and at varying amplitudes of the sinuous distribution pattern. The use of a feed hopper or backing plate, with ribbon type tow is necessary in controlling the size and number of ripples or bends in the distribution pattern of the material on the conveyor. When this mode of rearranging the tow distribution on a dryer conveyor is practiced, wet spots that remain in a tow advance into a redistributing device which works the tow in a manner to disturb and rearrange the filaments thereof. After being redeposited on the conveyor, the more moist sections of the tow occur in a difi'erent position relative to the bends of the newly formed distribution pattern and dry more readily.

A dryer system operated according to the invention is particularly useful when drying the bulky type of the filamentary materials such as roving, sliver and tow. Such a drying process is characterized by its economical utilization of equipment and the floorspace, and great uniformity in the dryness of the material handled.

Because of the increased drying rate obtained strand on edge thereof.

made without departing from the spirit and scope of the invention as defined in the appended claims.

We claim:

1. A method of drying a bulky filamentary running strand comprising the steps of pressing the strand into a flat band, continuously carrying the flattened strand while supported in a narrow zig-zag pattern through a drying region from a feed region, the Width of said zig-zag pattern being restricted to that which produces substantial self-support of the strand on an edge thereof.

2. A method of drying a bulky filamentary running strand comprising the steps of pressing the strand into a flat band, continuously carrying the flattened strand while supported in a narrow zig-zag pattern through a convection drying region from a feed region, continuously disrupting the zig-zag pattern of the flattened strand and reforming it into another zig-zag pattern, and carrying the strand through another convection drying region, the width of the zig-zag pattern in each case being restricted to that which produces substantial self-support of the flattened 3. A method of drying a bulky filamentary running strand comprising the steps of forming the strand into a flat band, continuously depositing the strand in a zig-zag pattern on asurface in continuous movement through a convection drying region, the width of said pattern being restricted to that which produces substantial selfsupport of the flattened strand on an edge therei. A method of drying bulky filamentary running strand comprising the steps of forming the strand into a flat band, continuously depositing the strand in a zig-zag pattern on a surface in continuous movement through a convection drying region, continuously removing the strand from the surface to dissipate the zig-zag pattern and depositing it on the surface in another zigzag pattern, the width of said patterns each being restricted to that which produces substantial self-support of the flattened strand on an edge thereof.

5. The method of drying a bulky filamentary running strand comprising the steps of pressing the strand into a flattened ribbon-like condition, continuously advancing an upwardly facing continuous surface through a convection drying region, feeding the strand from a fixed station onto the surface by progressively arranging the flattened strand in a zig-zag pattern of width substantially no greater than that needed to form the bends of the pattern and flattened portions between the bends which render the strand substantially self-supporting when standing on an edge thereof and then progressively collecting the flattened and sinuously-formed strand on the surface with the edges thereof disposed in substantially vertical relationship, removing the strand from the surface and reforming it into another similar pattern to form bends in the strands at different points than the bends of the previous pattern.

6. A drying apparatus comprising an endless conveyor and apparatus for handling at least one running strand of bulky filamentary material comprising a feed device having a strand discharging portion which is reciprocable with respect to the movement of the conveyor, a pair of nip rolls associated with the feed device for flattening the strand, at least one device for removing the strand from the conveyor and redistributing the strand thereupon, said device spaced over the conveyor and spaced from the feed device in the direction of conveyor movement, said redistributing device also having a strand discharging portion which is reciprocable in a direction transverse to the direction of movement of the conveyor.

7. A drying apparatus for handling at least one running strand of bulky filamentary material comprising an endless conveyor, a feeding device having a strand discharging portion which is reciprocable with respect to the direction of movement of the conveyor, at least one device spaced over the conveyor and spaced from the feed device in the direction in which the conveyor is movable for withdrawing the strand from and discharging it toward the conveyor, said second-named device also having a strand discharging portion for each strand handled by the feeding device which is reciprocable in a direction transversely of direction of conveyor movement, and stationary guide means mounted between each of said devices and the conveyor for supporting a plurality of folds of the material of each strand between each of the devices and the conveyor prior to being discharged thereonto.

8. A drying apparatus as in claim '7 wherein the guide means is a hopper extending transversely of the conveyor.

9. A drying apparatus as in claim 7 wherein the guide means is a hopper having strand-receiving and strand-discharging portions, said hopper extending transversely of the conveyor and a fold-supporting surface therewithin which is inclined with respect to a plane that is transverse and perpendicular to the conveyor so that the discharge portion of the hopper overhangs a more advanced section of the conveyor than the strand-receiving portion.

10. A method for drying a bulky filamentary running strand comprising the steps of advancing an upwardly-facing continuous supporting surface through a convection drying region, pressing the strand into a flattened condition .and discharging it toward the surface, reciprocating the flattened strand in a direction that is transverse with respect to its movement toward the surface and generally normal to the oppositely-facing flattened surfaces of the strand to arrange the strand in a zig-zag pattern having a width substantially no greater than that needed to form the bends of the pattern and flattened portions between the bends which render the strand substantially self-supporting when stood on an edge thereof, depositing the flattened and sinuously-formed strand on the surface with the edge thereof disposed in substantially vertical relationship with respect to each other, and removing the strand from the surface, flattening it, and reforming it onto a more advanced portion of the surface in similar pattern to form bends in the strand in different points than the bends in the previous pattern.

11. A method of drying bulky filamentary running strand comprising the steps of continuously pressing the strand into a flattened condition, continuously arranging the strand in sections by reciprocating the strand in a direction transverse to its direction of advancement and normal to the flattened surfaces of'the strand to fold the strand at linearly-spaced portions crosswise of its flattened surfaces, depositing the folded sections in a collection region, discharging the strand from the collection region onto a perforate surface having unidirectional movement, regulating the rate of movement of the surface to maintain the strand in substantially the folded condition produced within the collection region with the folded sections standing on edge in substantially self-supporting condition, carrying the strand on the perforate surface through a convection drying region, continuously removing the strand from the surface, then pressing and redepositing the strand in folded self-supporting sections on the perforate surface as hereinbefore defined, and passing the strand through another convection drying region.

12. A drying apparatus for handling at least one strand of bulky filamentary material comprising an endless conveyor; a feeding device comprising a pair of nip rolls spaced above the conveyor, and a pendulum-type chute positioned to receive the strand from the rolls and to discharge it toward the conveyor, the chute being pivotable with respect to a pivot axis which is spaced above the conveyor and parallel to the direction of its movement; and at least one device spaced over the conveyor and spaced from the feeding device in the direction of conveyor movement for withdrawing the strand, and redistributing the strand upon, the conveyor; said redistributing device having a strand discharging portion for each strand handled by the feed device which is reciprocable in the direction transverse to the direction of conveyor movement.

13. A drying apparatus for handling at least one running strand of bulky filamentary material comprising an endless conveyor, a feeding device having a strand discharging portion which is reciprocable with respect to the direction of movement of the conveyor and supported above the conveyor, and at least one device spaced over the conveyor and spaced from. the feed device in the direction of conveyor movement for withdrawing the strand upon, the conveyor, said redistributing device having a strand handling portion for each strand handled by the feed device, such strand handling portion comprising a pair of nip rolls and a support therefor which is reciprocable in a direction transverse to the movevice having a strand discharging portion which is reciprocable with respect to the direction of movement of the conveyor and supported above the conveyor; and at least one device spaced over the conveyor and spaced from the feed device in the direction of conveyor movement for withdrawing the strand from, and redistributing the strand upon, the conveyor, the feeding device and the strand redistributing device each comprising a carriage supported above the conveyor, a pair of nip rolls mounted on the carriage for each strand handled by the apparatus, and means for driving the nip rolls and for reciprocating the carriage in a direction transverse to the movement of the conveyor.

15. A method of drying a bulky filamentary running strand comprising the steps of continuously advancing an upwardly-facing continuous surface through a convection drying region, feeding the strand from a fixed station onto the surface in a zig-zag pattern of width substantially no greater than that needed to form the bends of the pattern, and removing the strand from the surface and forming it into another pattern of different width than that of the firstformed pattern to form bends in the strand at different points than the points at which the bends occurred in the previous pattern.

16. A method of drying a bulky filamentary running strand comprising the steps of continuously advancing an upwardly-facing continuous surface through a convection drying region, feeding the strand from a fixed station onto the surface in a zig-zag pattern of width substantially no greater than that needed to form the bends of the pattern, removing the strand from the surface and reforming it into another pattern wherein the number of transverse sections per unit length of the secondformed pattern diiiers from that of the firstformed pattern to form the bends in the strand in the second-named pattern at different points than the points at which the bends occurred in the previous pattern.

WALLACE A. KNOPP.

THOMAS L. NASH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,303,476 Kornegg Dec. 1, 1942 2,325,544 Redman July 27, 1943 2,379,824 Mummery July 3, 1945 2,390,572 Brabander Dec. ll, 1945