US3867741A

US3867741A - Method of aerodynamic formation for a fibrous layer from fibers treated on a carding machine and apparatus for performing this method

Info

Publication number: US3867741A
Application number: US450153A
Authority: US
Inventors: Veniamin Dmitrievich Frolov; Fedot Evdokimovich Yatsenko; Viktor Vladimirovich Pertsev; Valery Dmitrievich Rubtsov; Vitaly Alexandrovich Belyankin; Viktor Vasilievich Matveev; Max Khatskelevich Bernshtein
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-04-13
Filing date: 1974-03-11
Publication date: 1975-02-25
Anticipated expiration: 1992-02-25

Abstract

A method of aerodynamic formation of a fibrous layer and an apparatus for performing same are adapted for joint operation with a carding machine wherein fibres are doffed off the main drum of the carding machine in at least two points at different speeds and in different directions by means of doffer rollers rotated at different angular speeds in opposing directions. The fibres doffed in these two points are conveyed in separate air streams produced by rotary air blowers mounted internally of the respective condensers from the points of doffing toward these condensers. On the latter, the fibres from layers, and the orientation of the fibres in one layer are different from that in the other layer. The two layers thus formed are combined into a single common layer on a delivery conveyor which carries them away for subsequent treatment.

Description

United States Patent 1191 Frolov et al.

METHOD OF AERODYNAMIC FORMATION FOR A FIBROUS LAYER FROM FIBERS TREATED ON A CARDING MACHINE AND APPARATUS FOR PERFORMING THIS METHOD Inventors: Veniamin Dmitrievich Frolov, ulitsa 2 Lagernaya, 55, kv. 57; Fedot Evdokimovich Yatsenko, ulitsa 2 Lagernaya, 50, kv. 39; Viktor Vladimirovich Pertsev, ulitsa 2 Lagernaya 50, kv. 12; Valery Dmitrievich Rubtsov, ulitsa 2 Lagernaya, 53, kv. 46; Vitaly Alexandrovich Belyankin, ulitsa 2 Lagernaya, 46, kv. 15, all of lvanovo; Viktor Vasilievich Matveev, Michurinsky prospekt, 30, kv. 55; Max Khatskelevich Bernshtein, Michurinsky prospekt, 16, kv. 26, both of Moscow, all of USSR.

Filed: Mar. 11, 1974 Appl. No.: 450,153

Related US. Application Data Continuation of Ser. No. 351,005, April 13, 1973, abandoned.

us. c1. 19/106 R, 19/156.4 Int. Cl D0lg 15/46, D01 g 25/00 Field of Search 19/106 R, 156-1564,

[56] References Cited UNITED STATES PATENTS 1,683,812 9/1928 Walsh 19/106 R 1,833,811 11/1931 Allen et al. 19/106 R FOREIGN PATENTS OR APPLICATIONS 204,910 6/1968 U.S.S.R. 19/106 R 209,243 7/1968 U.S.S.R. 19/106 R Primary ExaminerDorsey Newton Attorney, Agent, or FirmHolman & Stern [57] ABSTRACT A method of aerodynamic formation of a fibrous layer and an apparatus for performing same are adapted for joint operation with a carding machine wherein fibres are doffed off the main drum of the-carding machine in at least two points at different speeds and in different directions by means of doffer rollers rotated at different angular speeds in opposing directions. The fibres doffed in these two points are conveyed in separate air streams produced by rotary air blowers mounted internally of the respective condensers from the points of doffing toward these condensers. On the latter, the fibres from layers, and the orientation of the fibres in one layer are different from that in the other layer. The two layers thus formed are combined into a ,7

single common layer on a delivery conveyor which carries them away for subsequent treatment.

7 Claims, 7 Drawing Figures PATENTEB FEB 2 5 I975 SHtH U HF PATENTEB FEB 2 5 I95 SHEET 5 BF 1 METHOD OF AERODYNAMIC FORMATION FOR A FIBROUS LAYER FROM FIBERS TREATED ON A CARDING MACHINE AND APPARATUS FOR PERFORMING THIS METHOD This is a continuation of application Ser. No. 351,005

filed Apr. 13, I973, now abandoned.

BACKGROUND OF THE INVENTION The present invention relates to methods of aerodynamic formation of a fibrous layer from fibres treated on a carding machine and to apparatus for performing such methods, employed in the textile and related industries for production of non-woven materials, artificial leather, industrial cloth, filters and like articles and materials.

PRIOR ART At present, known in the art is a method of aerodynamic formation of a fibrous layer, comprising the steps of doffing the fibres from the main drum of a carding machine and conveying them in an air stream toward a rotating condenser, with there being formed on the surface of this condenser, a fibrous layer forwarded for further treatment.

This known method is performed by an apparatus for aerodynamic formation of a fibrous layer, associated with a carding machine, which comprises a doffer roller mounted adjacent to the main drum of this carding machine, anair shaft, a condenser mounted at the outlet of this air shaft, a conveyor for delivering the layer formed on the condenser and a closed system of air conduits.

The condenser receives thereinside a rotary air blower.

However, a fibrous layer produced in accordance with the abovedescribed known method by the stated apparatus has been found to be of insufficiently high quality, when the productivity of the associated carding engine is relatively high, since doffing of the fibres from the main drum of the carding machine in a single point would not ensure complete doffing of the fibres. Those of the fibres which are not doffed are returned for repeated treatment.

In addition, with only onedoffer roller operating, the stream of fibres doffed from the main drum cannot be adequately uniform in length and width. This is explained by the fact that loading of the main drum with fibres has a periodic character, owing to a non-uniform charging of the carding machine, to non-uniform spacing of the working members of the latter and to an inevitable play of these working members. This periodic character of the loading of the main drumpredetermines a periodic character of the doffing of the fibres. It is possible to vary this periodicity (i.e., the wavelength of this periodicity) by varying the mode of the rotation of the doffer roller. The direction of the rotation of the doffer roller influences to a considerable degree the character (the structure) of the stream of fibres doffed from the main cylinder. Rotation of the doffer in opposition to that of the main drum leads to doffing of the upper layer of the fibres from the main drum, which results in a more regular character of the stream of fibres which is doffed. Should the doffer roller be rotated in the same direction with the main drum and at a slightly higher speed, the layer of fibres would be doffed from the depth of the clothing of the main drum, but the regularity of this layer would be poorer than that achieved by rotation of the doffer and of the main drum in opposition to each other.

Thus, the provision of a single doffer roller results in a specific degree of regularity and a specific structure of the stream of doffed fibres.

Furthermore, a single air shaft does not provide for a high quality of the fibrous layer, when the productivity of the carding machine is relatively high, since it has been found that a high-quality regular layer is formed in an air shaft when the concentration of fibres in the stream of the fibres (the amount of fibres in a unit of the volume of the air) is low. With the concentration increasing, there is a tendency of plait formation and of the fibres accumulating into knots.

The abovesaid affects to a great degree the uniformity and the structure of the fibrous layer formed on the condenser. Therefore, to attain a high-quality layer, particularly, when fine. fibres are treated, it becomesnecessary to bring down the productivity of the carding machine.

Furthermore, the structure and the uniformity of the fibrous layer is influenced to a considerable degree by the length of the air shaft, namely by the spacing between the doffing point and the condenser. When the air shaft is relatively long, the fibres carried by the air stream become mainly oriented so that when they settle on the condenser, their axes are parallel to that of the condenser. On the other hand, in air shafts of small length the fibres are not given time to re-orient themselves and, therefore,-they settle on the surface of the condenser with their axes mainly oriented laterally in respect of the axis of the condenser, i.e., the'direction of the fibres is the same, as on the clothing of the carding machine. Consequently, the fibrous layer displays greater strength either lengthwise or crosswise. The length of the air shaft also defines the quality of the fibrous layer, as far as a uniform distribution of the fibres in the layer is concerned. In long air shaft, the fibres have enough time to re-orient themselves in the air stream, and, therefore, the uniformity of the fibrous layer attains the character of the uniformity of the air stream. In shorter air shafts, the fibres have no time to re-orient in correspondence with the character of the air stream, and therefore, they reach the surface of the condenser with those elements of non-uniformity which they had in the carding machine. Thus, a longer air shafts becomes preferable when the devices for forming the air stream ensure a high degree of uniformity of this air stream, whereas the carding machine yields poor uniformity. On the other hand, shorter shafts are preferable .when the air stream is nonuniform across the width of the air shaft, and it is desirable to retain the ability of the carding machine to level out the fibrous layer.

Uniformity of the thickness of the fibrous layer is influenced by the shape of the air shaft.

The hitherto known shafts are either of the same cross-sectional area throughout their entire length, or else become wider toward the condenser.

When the air-fibre mixture moves along an air shaft having a permanent cross-sectional area, the resistance to its progress in different zones is also different. Nearer to the walls of the air shaft, this resistance is higher than in the central zone. Consequently, the sides of the fibrous layer are liable to get thinner than the central portion thereof. When the air-fibre mixture moves along a widening air shaft, this effect of thinning sidesbecomes even more pronounced, which means that the sides of the fibrous layer become even thinner. Therefore, to eliminate this non-uniformity, the sides of the fibrous layer leaving the machine are trimmed away, whichresults in considerable waste.

As'the fibres are acted upon by the clothing of the working members of the carding machine and by one another, they accumulate. static charges. Therefore, when the fibres leave the clothing of the doffer roller, they are liable to form large knots or plaits. This might result in a poor quality of the fibrus layer on account of local thickening and thinning thereof, whichinay become quite noticeable.

OBJECTS AND SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of aerodynamic formation of a fibrous layer and an apparatus for performing this method which results in a fibrous layer with an improved uniformity of distribution of the fibres therein, improved isotropy (i.e., equal strength in every direction), in combination with a high productivity of the process, increased weight of a square meter, of the layer, as well as provi-- sions for varying the width of the layer being produced.

With the above and other objects in view, the invention resides in a method of aerodynamic formation of a fibrous layer from fibres treated on a carding machine, comprising the steps of doffing the fibres from the main drum of the carding machine and conveying said fibres in an air stream toward a rotating condenser, on the surface of which a layer is formed from said fibres, and conveying said layer for subsequent treatment, in which method, in accordance with the present invention, the doffing of the fibres from said main drum of said carding machine is effected in at least two points, with the fibres being doffed in said at least two points at different speeds and indifferent directions.

In accordance with the invention, conveying of the doffed fibres from said two points is effected in individual respective air streams toward individual condensers over different distances from the respective doffing points, whereby the fibres in the respective layers on the surfaces of said condensers acquire different orientation, after which the thus formed layers are combined into a single common layer.

The invention is further characterized by the fact that in the process of conveying the fibres from the doffing points toward the condensers, the concentration of the fibres across the width of the stream is gradually increased by converging this air stream toward the condenser.

In an apparatus for performing the herein disclosed method, there is included a doffing roller mounted adjacent to the main drum of the carding machine, an air shaft, a condenser mounted at the outlet of said air shaft, said condenser receiving thereinside a rotary air blower, a closed system of air conduits, and a conveyor adapted to deliver the fibrous layer formed on said condenser, in which apparatus, in accordance with the invention, there are mounted adjacent to the main drum of .said carding machine at least two doffing rollers rotatable in opposite directions and at different angular speeds, the respective air shafts associated with said at least two doffing rollers being of different lengths and being mounted, together with their respective doffing rollers and condensers, to the same side of said main drum of the carding machine one above the other. Furthermore, said delivery conveyor is arranged intermediate of said respective condensers so that the fibrous layers formed on said condensers are forwarded onto said conveyor, where they combine into a single common layer.

Thus, due to the fibres being doffed from the main drum of the carding machine at two points by the two doffer rollers mounted adjacent to the main drum, there is stepped up the factor of removing the fibres from the main drum, which reduces loading of the main drum with the residual fibrous layer, and, hence, improves the carding ability of the carding machine, and, ultimately, its productivity.

With the fibres being doffed at these two points at different speeds and in opposing directions, the streams of fibres originating in these two points have a different structure and a different character of non-uniformity, the two streams, as they are subsequently combined together, forming a fibrous layer which has a uniform structure and uniform thickness both longitudinally and laterally.

With the fibres being conveyed in two separate air streams toward two individual condensers over different lengths from the respective doffing points by the provision of two air shafts with different lengths, there are formed on the respective condensers fibrous layers that have different patterns of the arrangement of the fibres, since the fibres conveyed through the longer shaft are given enough time to re-orient, whereby they settle on the respective condenser, to a major degree, axially of this condenser, whereas the fibres conveyed through the shorter air shaft do not have time to change the orientation they have been given in the carding machine, and settle on the respective condenser, also to a major degree, transversely of its axis. By combining the fibrous layers delivered by the respective condensers into a single common layer, the latter has therein fibres which are oriented both longitudinally and laterally thereof, whereby the layer displays substantially equal strength in these directions. Moreover, the combination of two fibrous streams into a single layer results in an increased weight of a square meter of this layer.

With the fibres being conveyed through two air shafts simultaneously, the capacity of the entire apparatus can be increased, as well as its productivity.

The invention is further characterized in that the air shafts are of a structure providing for reducing gradually their cross-sectional area in the vicinity of the respective condensers.

According to one embodiment of the presentinvention, this gradual reduction of the cross-sectional passage area of an air shaft is attained by the shaft converging in the direction from the doffer roller toward the condenser. 1

According to an alternative embodiment of the pres- I jacent to the walls of such shafts. Consequently, the thickness of the fibrous layer being formed is practically the same at the sides of the layer and at the center thereof.

By varying the degree of the reduction of the crosssectional area of the shaft, it is possible to vary the width of the fibrous layer being formed.

The invention is further characterized in that there are ionizers mounted adjacent to the doffer rollers, at the inlets of the respective air shafts.

The ionizers remove the static charges off the fibres, and, therefore, prevent the formation of plaits and knots.

To summarize, the present invention results in a fibrous layer with an improved uniformity of the distribution of the fibres therein, improved isotropy (i.e., equal strength in all directions), in combination with a high productivity of the entire process. Furthermore, the invention produces fibrous layers with an increased weight of a square meter of the layer, as well as with variable width of this layer.

The present invention will be further described in connection with an embodiment of the method of aerodynamic formation of a fibrous layer and of an appara- BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinally sectional view of an apparatus for aerodynamic formation of a fibrous layer, embodying the invention;

FIG. 2 is a left-hand side view of the apparatus shown in FIG. I;

FIG. 3 shows schematically the converging air shaft of the apparatus;

FIG. 4 is a cross-sectional view of the condenser of the apparatus shown in FIG. 1;

FIG. 5 is asectional view taken along line VV of FIG. 4;

FIG. 6 is a right-hand side view of the apparatus shown in FIG. 1; and

FIG. 7 illustrates in graphical form the distribution of the stream of fibres across the width of the air shaft.

DETAILED DESCRIPTION OF THE DRAWINGS Referring now in particular to the appended drawings, the apparatus for aerodynamic formation of a fibrous layer from fibres treated on a carding machine is arranged adjacent to a main drum 1 (FIG. 1) of the associated carding machine which is not shown in the appended drawings for the sake of clarity.

There are mounted to one side of the main drum 1,

I a pair of doffer rollers 2 and 3, a pair of .respective air shafts 4 and 5, a pair of

condensers

6 and 7, a pair of closed systems 8 and 9 of air conduits and a conveyer 10 for delivering the fibrous layers formed on the

condensers

6 and 7.

The doffer roller 2, the air shaft 4, the condenser 6 and the system 8 of closed air conduits are positioned, respectively, above the doffer roller 3, the air shaft 5, the condenser 7 and the system 9 of closed air conduits.

It should be understood that the herein disclosed apparatus for aerodynamic formation of'a fibrous layer may include a greater number of doffer rollers, air shafts and condensers.

The doffer rollers 2 and 3 are mounted adjacent to the main drum 1 either at the same spacing therefrom,

or at different spacings, with the exact spacing of the doffer rollers 2 and 3 from the main drum 1 depending mainly on the amount of fibres which is to be removed from the main drum by the respective ones of the doffer rollers 2 and 3.

The doffer rollers 2 and 3 have appropriate clothing tightened thereabout and are rotated at different angular speeds in opposite directions. The direction of the rotation of the doffer roller 2 is indicated with an arrow line A, while that of the doffer roller 3 is indicated with an arrow line B.

Rotation is transmitted to the doffer rollers 2 and 3 from the main drum 1 of the carding machine through Vee-belts 11 (FIG. 2), a drive pulley l2, Vee-belts I3 and a pair of driven

pulleys

14 and 15. The angular speed of the rotation of the doffer rollers 2 and 3 can be thus selected and varied by appropriate selection and replacement of the respective driven pulleys l4 and 15. The Vee-belts 13 are tensioned by a tensioning roller 16.

Each one of the air shafts 4 and 5 (FIG. 1) has an inlet and an outlet, with the outlets of the shafts adjoining, respectively, the doffer rollers 2 and 3, and the outlets of these shafts adjoining, respectively, the

condensers

6 and 7, the shafts 4 and 5 in the areas at which they adjoin the respective doffer rollers 2 and 3 communicating with the respective systems 8 and 9 of closed air conduits, or ducts.

The shafts 4 and 5 have different lengths indicated in the appended drawings as L and L,, respectively, with L being greater than L,. It is quite immaterial for the purposes of the present invention which of the shafts 4 and 5 has a greater length.

The air shafts 4 and 5' (FIG. 3) have a structure providing for a gradual reduction ofv the cross-sectional area of the shafts across the width thereof toward the

respective condensers

6 and 7. v

Gradual reduction of the cross-sectional area of the air shafts 4 and 5 across the widths thereof is effected by the shafts converging in the direction from the respective doffer rollers 2 and 3 toward the

condensers

6 and 7.

To effect converging of the airshafts, side walls 17 thereof are pivotally mounted tothe top and bottom walls of the shafts in the areas where the latter adjoin the respective doffer rollers. By pivoting the side walls 17 about pivots 18 toward each other, the crosssectional area of the air shaft across the width thereof is varied, i.e., the air passage area of the air shaft is gradually reduced, which promotes an increase of concentration of the fibres adjacent to the walls of the shafts.

Alternatively, this gradual reduction of the crosssectional area of the air shafts 4 and 5 across the width thereof can be effected with the help of arcuate baffles 19 (FIG. 4) mounted interiorly of the

condensers

6 and 7, with the baffies being movable toward each other axially of the respective condensers by adjustment screws 20.

Each' of the

condensers

6 and 7 includes a rotatable perforated cylindrical shell 21. l

The shell 21 is rotated from an electric motor 22 (FIG. 6) of the associated carding machine through a system of Vee-belts, a variable-ratio gear 23 (FIG. 1), chain transmissions 24 and a worm reducer 25 (FIG. 2).

; Mounted interiorly of each one of the condensers 6 and 7 (FIG. 4) is an air blower 26 of a rotary type.

Each air blower 26 includes a pair of rotors 27 which, when rotated, rarefy the air inside the condenser, whereby air is continuoulsy sucked into the condenser through its perforated shell 21.

The rotors 27 of the

condensers

6 and 7 are rotated, respectively, from individual electric motors 28 (FIG. 2) and 29 (FIG. 6) through respective Vee-belts 30 (FIG. 2) and 31 (FIG. 6) and pulleys 32, 33 (FIG. 2) and 34, 35 (FIG. 6).

For the rotors 27 to produce directed motion of air from the respective doffer rollers 2 and 3 (FIG. 1) through the air shafts 4 and and the

condensers

6 and 7, there is mounted interiorly of each one of these condensers a stationary casing 36 having made therein, in the opposite sides of the rotors 27, suction ports 37 (FIG. 4) and exhaust ports 38, with the length of these ports, as well as the length of the rotors 27 being equal to the working width of the associated carding machine.

The suction ports 37 (FIG. 1) face the areas at which the

respective condensers

6 and 7 adjoin the air shafts 4 and 5.

The exhaust ports 38 communicate, respectively, with the systems 8 and 9 of closed air conduits through which the air stream generated by the rotating rotors 27 is directed toward the doffer rollers 2 and 3 and participates in the removal of the fibres off these doffer rollers, helping the air stream sucked in through the air shafts by the same rotors. Arrow lines C indicate the flow direction of the air streams.

Each one of the systems 8 and 9 of closed air conduits has an inlet portion 39 communicating with the respective exhaust port 38 and including a diverging portion 40 wherein both the speed and the pressure of the air stream are gradually reduced. The diverging portion 40 adjoins the outlet portion 41 of the same air conduit, of which the flow passage area gradually diminishes, with the outlet 42 of this portion adjoining the area of the doffing of the fibres and communicating with the inlet of the respective air shaft. Thus, the speed of the air stream passing through the outlet 42 is increased.

The width of the inlet portion 39 of the air conduit and of the outlet portion 41 thereof is not below the working width of the associated carding machine.

There are layer-compacting rollers 43 mounted intermediate of each one of the

condensers

6 and 7 and the respective inlet portions 39 of the air conduits, as well as in the areas at which the air shafts 4 and 5 adjoin these condensers. Each roller 43 is a rubber-coated cylinder in contact with the periphery of the shell 21 of the respective condenser and is rotatable thereby.

There are also compacting rollers 44 mounted intermediate of the respective shells 21 and the stationary casings 36 of the air blowers 26, adjacent to the suction port 37 and to the exhaust port 38 (FIG. 4). Each compacting roller 44 is likewise a rubber-coated cylinder in rolling contact with the shell 21 and rotatable thereby. At the level of the suction port 37 and of the exhaust porti 38, the casings 36 have grooves 45 (FIG. 5) therein, to accomodate the arcuate baffles 19. The baffles, as it has been described hereinabove, are movable toward each other axially of the condenser with the help of adjustment screws 20. Tha latter are rotatably supported in the end faces of the casings 36 adjacent to the baffles 19, with each adjustment screw 20 being threadedly received in a threaded opening 46 in a handle 47 provided on the respective baffle 19. As the baffles 19 are moved toward one another, they partially close off the

ports

37 and 38, thus reducing the width of the air streams being, respectively, sucked in and exhausted, and simultaneously increasing the speed thereof. FIG. 3 illustrates the variation of the air stream, defined by the ratio 1,:1 depending on the degree to which the baffles close off the

ports

37 and 38, where l, is the width of the air stream adjacent to the doffer rollers 2 and 3, I is the width of the air stream adjacent to the

condensers

6 and 7.

It is possible to move the baffles 19 toward each other and at the same time to pivot correspondingly the side walls 17 of the air shafts 4 and 5, which means that the degree of the pivoting of the walls 17 toward the center of the air shafts should correspond to the displacement of the baffles 19 toward each other.

Positioned adjacent to the outlets 42 and the respective doffer rollers 2 and 3 (FIG. 1) are ionizers 48 of either electric or radioactive action, adapted to relieve the fibres being doffed from static charges.

The conveyor 10 delivering the fibrous layers formed on the

condensers

6 and 7 is mounted therebetween on a support frame 49 which latter also supports the

condensers

6 and 7, the air shafts 4 and 5, the systems 8 and 9 of closed air conduits and the doffer rollers 2 and 3.

The conveyor 10 adjoins the condenser 7, so that the fibrous layer formed on the latter is forwarded directly onto the belt of this conveyor. To forward onto this conveyor 10 the fibrous layer formed on the condenser 6, there is positioned between this condenser and the conveyor 10 a tray 50 which directs the last-mentioned layer onto this conveyor. To effect this directed motion of the layers leaving the

respective condensers

6 and 7 onto the conveyor 10, the condensers should be rotated in opposite directions. Thus, the condenser 6 is rotated in the direction indicated with an arrow line D, whereas the condenser 7 is rotated in the direction indicated with an arrow line E.

With the

condensers

6 and 7 rotated in the aboveindicated directions, the formed layers are forwarded onto the conveyor 10, where they are combined into a single common layer and delivered by this conveyor for further treatment.

The hereinabove disclosed apparatus for aerodynamic formation of a fibrous layer operates, as follows.

Fibres carded by the carding machine are doffed from the main drum 1 in two points by the doffer rollers 2 and 3, respectively. The fibres are doffed in these two points at different speeds and in different directions. (The directions of the rotation of the doffer rollers 2 and 3 are indicated in the drawings with the arrow lines A and B, respectively). This ensures a high degree of removal of the fibres from the surface of the main drum, whereby the residual layer thereon is reduced, and, cosequently, there is increased the carding capacity of the machine and, hence, its productivity.

With the fibres being doffed in two different points at different speeds and in different directions, the two streams of fibres leaving the main drum 1 have the respective phases of the waves of the periodic nonuniformity, which is characteristic of the fibres on the surface of the main drum, shifted relative to each other, on account of the difference between the ratios of the speeds of the rollers 2 and 3 to that of the main drum 1. Besides, the structures of the fibre streams doffed by the rollers 2 and 3 are also different. Thus, the roller 2 removes from the main drum 1 mainly individual fibres carried by the very periphery of the clothing of the main drum 1, whereas the roller 3 doffs complexes of fibres which form the residual layer deeper in the clothmg.

The

condensers

6 and 7 housing thereinside rotating rotors 27, the suction in the suction port 37 and the pressure in the exhaust port 38 originate a directed motion of air through each one of the air shafts 4 and toward the

respective condensers

6 and 7, via the

airconduits

39, 40 and 41 toward the doffer rollers and again through the air shafts 4 and 5 toward the

condensers

6 and 7, i.e., the air stream is driven completely through a closed path.

The streams of fibres removed from the doffer rollers 2 and 3 are conveyed toward the

respective condensers

6 and 7 by individual air streams in the air shafts 4 and 5 over different distances from the points of doffing, with the distances being defined by the respective lengths L and L of the shafts 4 and 5. Therefore, there are formed on the shells 21 of the

condensers

6 and 7 fibrous layers having a different structure and degree of uniformity.

Thus, within the air shaft 4, the fibres are given time to re-distribute themselves'uniformly in the stream andto re-orient prior to their settling onto the shell 21 of the condenser 6, where they become oriented parallel to the axis of this condenser. Consequently, the fibrous layer formed on the condenser 6 displays greater strength in the transverse direction.

Within the shaft 5, on the other hand, the fibres are not given enough time to re-distribute themselves uniformly in the air stream and to change their orientation, whereby they settle on the shell 21 of the condenser 7 perpendicularly to the axis of this condenser. Consequently, the fibrous layer formed on the condenser 7 displays greater strength in the longitudinal direction.

Therefore, by effecting doffing of the fibres in two different points at different speeds and in different directions, as well by carrying the fibres in individual air streams in the air shafts 4 and 5 of different lengths,

there are formed on the condensers 6 and 7 a fibrous layer having different degrees of uniformity and structures. As parts of these shells 21 of the

condensers

6 and 7 internally of the apparatus are shielded by the casing 36, there is no air sucked in through the perforations of the shells in these areas, whereby in these areas the fibrous layers formed on the

respective condensers

6 and 7 freely leave the latter. The layer leaving the condenser 6 passes over the tray 50 and lays itself onto the conveyor 10, while the layer formed on the condenser 7 is directly taken by the conveyor 10. The layer passing over the tray 50 becomes superimposed on the conveyor over the layer that has been taken from the condenser 7. t

As these formed layers are thus combined on the conveyor 10, the different modes of the doffing of the fibres from the main drum 1 of the carding machine in the respective different points and the different modes of the conveying of the fibres throught the air shafts 4 and 5 result in a shifting of the periodic non-uniformity which may be characteristic of the operation of the carding machine, and, as these waves of non-uniformity in the abovesaid two layers have different amplitudes and are shifted in phase relative to each other, the combination of the two layers results in a levelling out of the final fibrous layer. I

With the air shafts 4 and 5 (FIG. 3) being of a structure providing for a reduction of the cross-sectional area thereof across the width, i.e., with the air shafts converging in their width toward the

respective condensers

6 and 7, the concentration of the fibres adjacent to the side walls 17 of the shafts increases toward the condensers, which results in a levelling out of the thickness of the fibrous layers being formed.

FIG. 7 illustrates in the form of a diagram the distribution of the stream of fibres across the width of the air shaft. Here a dotted line a-a shows distribution of the stream of fibres in an air shaft which is not converging. It can be seen that in this case the stream of fibres has at the sides thereof a smaller concentration of the fibres, than in the central portion, whereby the formed fibrouslayer has a correspondingly reduced thickness at its sides.

A solid line bb in the diagram illustrates the distribution of the stream of fibres in a converging shaft. In this case, as the air shaft converges, the concentration of the stream of the fibres across the width of the shaft gro'ws, particularly, at the sides of the stream, whereby the fibrous layers formed on the

condensers

6 and 7 have their thickness levelled out. I

. When the fibrous layers thus formed are treated on the successive pieces of equipment, the width of the layers may vary, with this variation being different for different types of fibres. As a result, there are finally produced ready materials of different width, which may be highly undesirable. Therefore, to obtain a final material of a required width, the width of the layers formed in the apparatus can be adjusted by adjusting the degree of the convergence of the air shafts, either by displacing the baffles l9 axially of the condensers toward each other, or by pivoting the side walls 17 of the air shafts 4 and 5, or else by both techniques simultaneously.

What is claimed is:

1. A method of aerodynamic formation of a fibrous layer from fibres treated on a carding machine, comprising the steps of doffing the fibres from the main drum of said carding machine in at least two different points, the speed and the direction of doffing in said at least two points being different; conveying said fibres doffed in each one of said points in an individual air stream over paths of different lengths from the respective ones of said points toward rotating condensers,

forming on said condensers upon rotation thereof respective fibrous layers from said doffed fibres conveyed over'said different lengths, so that said fibres acquire in one of said layers an orientation which is different from the orientation of the fibres in the other one of said layers, combining said layers into a single common layer; delivering said layer for further treatment.

2. A method as claimed in claim 1, wherein during said conveying of the fibres from said respective doffing points toward said condensers the concentration of the fibres is gradually increased across the width of each said air stream, by converging said air stream toward said condenser.

3. An apparatus for aerodynamic formation of a fi brous layer from fibres treated on a carding machine comprisinga main drum; at least two doffer rollers arranged close to the main drum for rotation at a different speed and direction to doff the fibres from the main drum;-means to rotate each of said doffer rollers at a different speed and direction; two air shafts of different lengths, each air shaft having an inlet opening and an outlet opening, each of said shafts by said inlet opening adjoiningv acorresponding doffer roller and serving to transport fibres from the doffer rollers; two perforated rotary condensers for forming fibrous layers from said fibres and each of said condensers adjoining the corresponding said outletcopening of one of said air shafts; rotary type air blowers mounted inside said condensers and providing the movement of'the flows of air in said air shafts to doff the fibres from said doffer rollers and to transport said fibres from said doffer rollers toward said condensers; closed systems of air conduits, each being mounted near each condenser and serving to direct the air flow from said condensers toward said doffer rollers; a conveyor arranged between said condensers so that the fibrous layers formed on said condensers are fed onto said conveyor to be combined thereon into a single common layer; said doffer rollers,

air shafts, condensers and closed systems of air conduits being mounted to one side of said main drum, one above another.

4. The apparatus as claimed in claim 3 including arcuate baffles mounted in each of said condensers, said arcuate baffles being movable axially of said condenser towards each other to diminish the cross-section of the shaft as to its width. I

5 The apparatus as claimed in claim 3, wherein said air shafts are of a structure providing for reduction of the cross-sectional area across the width thereof toward the respective ones of said condensers.

6. The apparatus as claimed in claim 5, wherein said reduction of said cross-sectional area of said air shaft across the width thereof is effected by each said shaft converging in the direction from the respective one of said doffer rollers toward the respective one of said condensers.

7. The apparatus as claimed in claim 3, including ionizer means mounted adjacent to said doffer rollers at the inlets of the respective ones of said air shafts.

Claims

1. A method of aerodynamic formation of a fibrous layer from fibres treated on a carding machine, comprising the steps of doffing the fibres from the main drum of said carding machine in at least two different points, the speed and the direction of doffing in said at least two points being different; conveying said fibres doffed in each one of said points in an individual air stream over paths of different lengths from the respective ones of said points toward rotating condensers, forming on said condensers upon rotation thereof respective fibrous layers from said doffed fibres conveyed over said different lengths, so that said fibres acquire in one of said layers an orientation which is different from the orientation of the fibres in the other one of said layers, combining said layers into a single common layer; delivering said layer for further treatment.

3. An apparatus for aerodynamic formation of a fibrous layer from fibres treated on a carding machine comprising a main drum; at least two doffer rollers arranged close to the main drum for rotation at a different speed and direction to doff the fibres from the main drum; means to rotate each of said doffer rollers at a different speed and direction; two air shafts of different lengths, each air shaft having an inlEt opening and an outlet opening, each of said shafts by said inlet opening adjoining a corresponding doffer roller and serving to transport fibres from the doffer rollers; two perforated rotary condensers for forming fibrous layers from said fibres and each of said condensers adjoining the corresponding said outlet opening of one of said air shafts; rotary type air blowers mounted inside said condensers and providing the movement of the flows of air in said air shafts to doff the fibres from said doffer rollers and to transport said fibres from said doffer rollers toward said condensers; closed systems of air conduits, each being mounted near each condenser and serving to direct the air flow from said condensers toward said doffer rollers; a conveyor arranged between said condensers so that the fibrous layers formed on said condensers are fed onto said conveyor to be combined thereon into a single common layer; said doffer rollers, air shafts, condensers and closed systems of air conduits being mounted to one side of said main drum, one above another.

4. The apparatus as claimed in claim 3 including arcuate baffles mounted in each of said condensers, said arcuate baffles being movable axially of said condenser towards each other to diminish the cross-section of the shaft as to its width.

5. The apparatus as claimed in claim 3, wherein said air shafts are of a structure providing for reduction of the cross-sectional area across the width thereof toward the respective ones of said condensers.