US3884029A

US3884029A - Apparatus for ringless spinning of fibres

Info

Publication number: US3884029A
Application number: US367419A
Authority: US
Inventors: Josef Ripka; Jan Junek; Vaclav Vobornik; Ludmila Lihtarova; Frantisek Hortlik; Vaclav Brynda; Vladimir Ohlidal; Zdenek Korbar; Milos Vecera
Original assignee: Vyzkumny Ustav Bavlnarsky AS
Current assignee: Vyzkumny Ustav Bavlnarsky AS
Priority date: 1972-06-08
Filing date: 1973-06-06
Publication date: 1975-05-20
Anticipated expiration: 1992-05-20

Abstract

In a ringless fiber spinning machine the fibers are carded by a carding roller and are thereupon centrifugally discharged in a doffing zone in such a manner that the fibers scatter only slightly and advance along their centrifugal trajectory towards the inlet of the rotary spinning chamber of the machine.

Description

Ripka et al.

APPARATUS FOR RINGLESS SPINNING OF FIBRES Inventors: Josef Ripka; Jan Junek, both of Usti nad Orlici; Vaclav Vobornik, Letohrad; Ludmila Lihtarova, Usti nad Orlici; Frantisek Hortlik, Usti nad Orlici; Vaclav Brynda, Usti nad Orlici; Vladimir Ohlidal, Usti nad .Orlici; Zdenek Korbar, Usti nad Orlici; Milos Vecera, Usti nad Orlici, all of Czechoslovakia Assignee: Vyzkumny ustav Bavlinarsky, Usti nad Orlici, Czechoslovakia Filed: June 6, 1973 Appl. No.: 367,419

Foreign Application Priority Data [451 May 20, 1975 References Cited UNITED STATES PATENTS 3,439,488 4/1969 Bucil et a] 57/58.95 3,487,626 1/1970 Rajnoba et al 57/58.95 X 3,584,451 6/1971 Chrtek et al 57/58.95 3,624,995 12/1971 Rajnoha et a1 57/58.91 3,626,681 12/1971 Noruse 57/58.91 3,696,605 10/1972 Morikawa et al 57/58.95 3,712,042 1/1973 Chrtek et a1 3,750,380 8/1973 Mladek et al 57/58.95

Primary Examiner-J0hn W. Huckert Assistant ExaminerCharles Gorenstein Attorney, Agent, or Firm-Michae1 S. Striker [5 7 ABSTRACT In a ringless fiber spinning machine the fibers are carded by a carding roller and are thereupon centrifu- June 8, 1972 Czechoslovakia 3963 n discharged in a doffing Zone i such a manner June 8, 1972 Czechoslovakia 3965 that the fibers Scatter only Slightly and advance along their centrifugal trajectory towards the inlet of the ro- U.S. Cl. 57/58.9l; 57/58.95 tary Spinning chamber of h machine Int. Cl D0lh l/12 Field of Search 57/58.9l, 58.95 13 Clams, 15 Drawmg Flgures Pmmanwzw 3.884.029

SHEEI 2 {if 6 PATENTED HAY 2 0 i975 SHEET 4 OF 6 APPARATUS FOR RINGLESS SPINNING OF FIBRES BACKGROUND OF THE INVENTION The present invention related generally to a spinning machine for ringless spinning of fibers, and more particularly to a method of doffing fibers from the combing roller of such a machine, and to an apparatus for carrying out this doffing.

Ringless spinning, sometimes also referred to as open-end spinning, is well established in the art. Various different principles of operation for this type of spinning are known, but in all of them a separating device a carding or combing roller is used to separate the incoming fibrous sliver into its individual fibers before the latter can enter the rotary spinning chamber of the machine. Basically, the combing roller performs two different functions, namely one is to grip the fibers of the sliver and comb them out of the sliver so that they can be supplied in loosened-up and separated form into the spinning chamber or the like. The other function is to release these fibers at a certain distance from the point where they have been removed out of the fibrous sliver, and to pass them into an airstream which entrains them and carries them through an inlet channel into the spinning chamber.

As the art of ringless spinning has become more developed, performance requirements made of the equipment used for this purpose have increased steadily. Despite this, however, the known machines are not free of problems, particularly in the so-called doffing area, that is the area where the fibers are doffed or released from the combing roller. In particular, it has been observed that an increased amount of fibers circulates with the combing roller, that is not all fibers are released from the combing roller and those that remain on it continue to rotate with it and pick up others. This leads to an increasing frequency in the incidence of combing roller clogging.

Another problem is that the imperfect release of fibers from the combing roller results also in an increased wear of the inner walls bounding the cavity in which the combing roller rotates, and in particular in considerable wear of the cutter or edge which guides the fibers from the doffing zone into the inlet of the spinning chamber.

Theoretically, fiber doffing could be improved by providing an improved lining on the combing roller, that is the layer of material which is applied to the periphery of the combing roller and is provided with the teeth or projections which enter into the fibrous sliver and loosen the individual fibers thereof. However, in and of itself this change would not be sufficient to over come the problems existing in the art, and it is necessary to create favorable conditions for fiber release which go beyond a mere improvement in the teeth or needles on the combing roller.

It is also known from the prior art, for instance Czechoslovak Pat. Nos. 115,362 and 101,216, U.S. Pat. No. 689,556 and French Pat. No. 1,309,135, to provide a spiral wall of the inner cavity accommodating the combing roller with a continuously linked-up delivery channel entering into the rotary spinning chamber of analogous device. This solution has its own drawback, namely the fact that the fibers travel along a shorter or longer curved path very close to the inner wall of the inlet channel, or slide along the same. This means that they are under the influence of centrifugal forces while being retarded by the frictional effect between the fibers and the wall along which they slide. After a certain time the surface finish of the wall deteriorates and the fibers cannot properly slip along it, which is undesirable for obvious reasons.

Another attempt at improving the doffing area is disclosed in German allowed application Nos. 1,1 11,549 and 1,009,541. In these prior-art constructions a simple inclined connection of a short inlet channel is linked with a cylindrical cavity wherein the combing roller r0- tates. However, experience has shown that this can provide only for an imperfect fiber take-up.

German allowed application No. 1,420,169 and Swiss Pat. Nos. 456,414 and 464,026 provide still another solution, tangentially linking the inlet channel to the spinning chamber with the cylindrical cavity accommodating the combing roller. High-speed motion pictures taken of operating devices according to these teachings have shown, however, that even here imperfect doffing of fibers from the combing roller lining, and a considerable scattering of the fiber paths at their transition to the inlet channel of the spinning chamber, including the contact of the fibers with the walls of the channel, obtain. 0

All of these proposals represent closed-type devices with respect to the inlet of entraining air into the doffing area, while air penetrates into the inlet channel to the spinning chamber mostly through gaps in the device which includes the combing roller, especially at the area of the apparatus which feeds the fibrous sliver. From the viewpoint of energy required to operate these devices this is, of course, disadvantageous.

Czech Pat. No. 125,190 describes a further construction, utilizing a so-called direct channel wherein the inlet of air into the doffing area is solved by direct connection with the surroundings, that is with the ambient atmosphere. This apparatus has a rotary spinning chamber which operates at sub-atmospheric pressure and requires the velocity of air in the direct channel to exceed the circumferential velocity of the needle tips of the combing roller, in order to obtain reliable operation. Under conditions of current circumferential velocity of the needle tips from between 20 and 30 m/sec, the minimum air velocity should amount to at least 30 to 40 m/sec. Taking into account the usual type of spinning chamber fan, and a certain width of the combing roller which is necessary for faultless loosening of the sliver, as well as the indispensable cross-section of the direct channel at the doffing area, it is found that only a very small height for the direct channel cross-section can be utilized. Consequently, in this construction only a very narrow space for the outlet of fibers is available. The fibers, following their natural tendency to leave the combing roller lining, strike against the wall of the channel opposite the lining. If the height of the channel cross-section is limited, the magnitude of the central sector of the angle of the doffing area is limited as well, and the fibers that have not been picked up will strike with considerable frequency against the separating edge or blade. The worn edges of the separating edge or blade and of the channel walls in this type of apparatus convincingly indicate that this is what takes place. This is evidently undesirable, and the required high operating speed of the entraining air, in conjunction with the small cross section of the flat channel, represent drawbacks for the operation of the spinning unit as well.

It is thus clear that none of the prior-art devices provide for an optimum solution of the problem at hand, namely the doffing of fibers from the combing roller and their insertion into the inlet of the spinning instrumentality, such as a rotary spinning chamber.

SUMMARY OF THE INVENTION It is, accordingly, an object of the present invention to overcome the disadvantages of the prior art.

More particularly it is an object of the present invention to provide an improved method of doffing such fibers and providing for their insertion into the inlet of a spinning instrumentality.

A further object is to provide an improved apparatus which can carry the method into effect.

In keeping with these objects, and others which will become apparent hereafter, one feature of the invention resides, in a method of doffing fibers from a combing roller into an inlet of a rotary spinning chamber, in the step of centrifugally discharging the combed fibers from the combining roller into a doffing zone in such a manner that the fibers scatter only slightly, and advance along their centrifugal trajectory towards the inlet.

The present invention is based upon both experimental and theoretical knowledge of the doffing area operation within a ringless spinning unit, and is aimed at preventing contact of the fibers with the walls and the separately edge, to improve the passage of the fibers through the system and obtain their continuous movement with a minimum distortion in their form.

A further feature of the invention provides for the fibers to be thrown by centrifugal force through the surface air layer which travels with the combing roller, at the point where the already loose separated fibers pass into the doffing area, so that the fibers are entrained by an airstream which is admitted at the bottom of the doffing area by an intake channel. This airstream prevents the fibers from being drawn back against the lining of the combing roller, and entrains them and advances them through the inlet into the spinning instrumentality without permitting them to contact the wall opposite the combing roller and the separating edge.

According to another feature of the invention there is provided, adjacent the mouth of the air inlet channel, an air swirl field which deflects the airstream in the doffing area away from the surface air layer travelling with the lining of the combing roller.

A further feature provides for the fibers to be directed to the inlet opening leading to the spinning instrumentality, approximately at the middle of the height of this opening while making the fibers travel through the doffing area in a parallel stream airfield.

Further, the fibers are to be made to move through the inlet opening on a trajectory which is out of contact with the walls bounding the opening.

In the apparatus according to the present invention the construction is such that the magnitude of an angle enclosed between an imaginary tangent plane through the covering of the roller at the point where the fibers are released, and the wall which is opposite the covering, is in the range between and 20, preferably amounting to about The tangent to the trajectory at the point of intersection with the mouth is preferably parallel with the axis of the inlet opening to the spinning instrumentality.

The angle equalling the center angle in the doffing area reduced by the angle mentioned earlier and included between the imaginary tangent plane of the covering at the release point and the wall opposite the covering, is preferably larger than this last-mentioned angle. The sum of these angles, that is the last-mentioned angle and the one which is larger than it, is preferably higher than or equals 50, preferably being in the range from 60 to The distance of the imaginary perpendicular projections of the releasing point of the fibers, and of the fiber separating edge, onto the wall bounding the opening in which the combing roller rotates, is preferably less than the distance of the intersection point of a tangent plane with the same wall and with the aforementioned perpendicular projection of the separating edge onto this wall.

An effective embodiment is obtained if the air channel diameter is less than the minimum diameter of the doffing area and opens very closely to the releasing point of fibers from the lining of the lining of the combing roller.

A further embodiment provides for the distance of the intersection point of the axis of the inlet channel with the bottom of the doffing area from the lining of the roller to equal the height of the lining at the maximum, or else in thatthe ratio between the bottom surface and the air intake channel section is within the range 2: land 30: 1.

It is also advantageous if the circumferential distance around the combing roller from the end of the combing-out area to the point where the combing roller enters the airstream in the doffing area, exceeds the effective staple length of the fibers, and further if the circumferential distance around the combing roller from the point where the combing rollers enters the airstream in the doffing area up to the separating edge exceeds the effective staple length of the fibers, and a further if the inlet channel, the doffing area and the intake for the rotating spinning instrumentality are all cylindrical in form of tapered channels following continuously one another.

The diameter of the channel which delivers air to the doffing area should be less than the minimum diameter of the doffing area, its outlet being closely adjacent to the wall bounding the doffing area.

At the point where the fibers are released from the lining of the combing area an adjustable orifice plate may be mounted, having a smaller orifice cross section than the minimum diameter of the doffing area, with the position of the orifice plate being adjustable in order to allow favorable influencing of the air streaming within the fiber doffing area.

The wall may be provided with at least one air intake opening, or with at least one air discharge opening, or it may be provided with both inlet and discharge openings for the air.

The fiber releasing point in the doffing area may be limited by means of an insert in the channel through which the fibers advance, with the cross section of the insert being convergent.

Various of these features may be combined to provide a construction suitable for particular requirements and of great effectiveness.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself. however. both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a diagrammatic section through an apparatus according to the present invention, particularly intended to facilitate a better understanding of the situation obtaining in the fiber doffing area;

FIG. 2 is a diagrammatic section showing the fiber doffing area of the separating device of FIG. 1, with the fiber trajectories and their scattering field being marked;

FIG. 2a illustrates the fiber frequency distribution force within the scattering field;

FIG. 3 is a sectional view of the fiber doffing area, with the basic trajectory of the fiber stream being marked and shown to be passing through the center of the inlet leading to the spinning instrumentality;

FIG. 4 is a diagrammatic representation of the doffing area, having a direct channel and showing the parallel stream airfield, with a marked theoretical fiber trajectory curve and indicating the respective speeds;

FIG. 5 represents diagrammatically the geometric characteristics of the section of the fiber doffing area;

FIG. 6 shows a section of the fiber doffing area to which air is supplied by a channel having a smaller cross section than the smallest cross section of the doffing area;

FIG. 7 is a view analogous to FIG. 6 but showing the air channel to have a different position;

FIG. 8 represents a section of the doffing area and illustrates air entering via an adjusting orifice plate;

FIG. 9 is a cross section of the doffing area showing that the wall opposite the combing roller is provided with air intake openings;

FIG. 10 is a section of the doffing area showing the wall opposite the combing roller to be provided with air discharge openings;

FIG. 11 is a section of the doffing area created in a direct channel the section of which is narrowed down;

FIG. 12 represents a diagrammatic section of the doffing area with the trajectory of fibers and its tangent being indicated;

FIG. 13 is a diagrammatic section illustrating a further embodiment of the invention; and

FIG. 14 is a section taken along line XX of FIG. 13.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Before discussing the drawing in detail it is remarked that in view of the fact that the invention is concerned with a very specific aspect of a ringless spinning unit, a very concise description will be given of embodiments integrated with a spinning chamber of such a unit. However, it is again pointed out that instead of a rotary spinning chamber a different spinning instrumentality could be employed.

Referring now to FIG. 1 it will be seen that a body 1 of a separating unit is arranged adjacent to a rotary spinning chamber 2. Fibrous sliver enters through a condensing device 4, aided by the feeding roller 5 and the pressure element 6, and enters into the cylindrical cavity 17 in which the combing roller 8 is arranged which rotates about the axis 9. The cavity 7 is interrupted and open for the outlet of fibers through the doffing area 10, which is delimited at its upstream end by the loosening point 11 at which fibers l2 become separated from the lining 13 of the roller 8, and which at its downstream end is delimited by the separating edge 14.

The doffing area 10 is further delimited by the lining l3 and by the wall 15 which is opposite to the lining 13. It communicates with the inlet channel 16 for the inlet of air into the area at the loosening point. Air can be admitted either from the ambient atmosphere or from an air supply system. The mouth 17 of the channel 16 is diagrammatically indicated by a dashed line in FIG. 1. The doffing area 10 is connected with the inlet channel 18 at the zone of the separating edge 14 which can have various different forms. The mouth 19 of the channel 18 is again indicated by a dashed line. The fibers 12 admitted into the twisting device 2, such as a rotary spinning chamber, are formed in known manner into a yarn 20 which is withdrawn by the

rollers

38 and 39 and wound onto the bobbin 40.

FIG. 2 shows the basic trajectory 21 of the fibers as they are doffed from the cylindrical surface 22 of the lining 13 of the roller 8, and the upper limit 23 and the lower limit 24 of the fiber stream scattering, that is the range within the stream the fibers will scatter, are also shown in FIG. 2.

FIG. 2a is a diagrammatic illustration of the curve 211 showing the frequency distribution of fibers in the scattering field, as occurs in the situation obtaining in FIG. 2.

FIG. 3 illustrates a special case of the trajectory 21, which case is characteristic in an embodiment in which the height of the cross section of the inlet channel 18 at its mouth 19 is divided into two equal sectors C.

In FIG. 4 we have shown the trajectory 21 in a parallel air stream having the velocity v,, in a coordinate system x, y and with the starting point at the fiber releasing point 11, if the tangent plane 25 to the cylindrical surface 22 of the lining l3 encloses with the streaming di rection an angle A. The circumferential velocity of the combing roller 8 is v According to FIG. 5 the tangent plane 25 mentioned above intersects the wall 15 at the intersection point 26. The distance between the

mouths

17 and 19 is represented by the distance L 1719 in the doffing area 10, and the distance of the mouth 17 from the point of intersection 26 is designated by the length L 17-26. The center angle D corresponding to the length of the doffing area is divided into the angle A and the angle B =D A.

FIGS. 6 and 13 show an arrangement wherein the cross-section of the air inlet channel 16 at its mouth 17 is less than the minimum cross-section of the doffing area 10, and the mouth 17 is located adjacent to the fiber releasing point 11.

In FIG. 7 the air inlet channel 16 is arranged next to the wall 15, and in FIG. 8 the air inlet into the doffing area is controlled by an adjustable orifice plate 28 whose orifice 29 controls the airflow. The plate 28 is shiftable in the

guides

30 and 31.

In the embodiment of FIG. 9 intake openings 32 are provided for delivering air into the doffing area. These openings are located between the orifice 17 and the mouth 19 in the wall 15.

In FIG. 10 the wall is provided with air discharge openings 33 to permit discharge of the air from the doffing area 10.

According to FIG. 11 the channel 16 and the release point 11 are produced by providing an insert 35 of tapering cross-section in the running channel 34 in which the fibers advance.

FIG. 12 shows an arrangement wherein the direction of the tangent 37 to the fiber trajectory 21 at the point 36 which is the point of intersection of the trajectory 21 and the mouth 19- parallels the direction of the inlet channel 18.

In FIGS. 13 and 14 the air intake channel 16, the doffing area 10 and the inlet channel 18 are advantageously constructed as a system of cylindrical and tapered channels following continuously one another. The inlet part 160 of the air intake channel 16 for delivering of air can be formed as a recess 161, but instead a suitable regulating member 162 could also be provided in it, for instance a throttling valve which is diagrammatically illustrated in FIG. 13 and serves to regulate the air intake. Also, a suitable air filter (not illustrated) can be arranged in the recess 161 to prevent undesirable small particles of dirt and flying material from penetrating into the apparatus.

The air intake channel 16 suddenly emerges at its mouth 17 into the doffing area 10, the bottom 100 of which is oriented essentially perpendicularly to its longitudinal axis. The distance F (see FIG. 14) of the intersection point of the axis of the air intake channel 16 with the bottom 100 of the doffing area 10 from the lining 13 of the combing roller 8 equal half the height E of the bottom at its maximum, while the ratio of the bottom 100 surface and the cross section of the air intake channel 16 is within the range 2 l to 30 l..The inlet channel 18 is substantially tangential with respect to the lining 13 of the combing roller 8 and narrows in the direction towards the outlet of the body 1 of the combing apparatus.

The inlet channel 18, which forms at the bottom part of the body 1 the separating edge 14, has a slight inclination towards the spinning chamber 2, which inclination amounts to 2045 with respect to a perpendicular plane to the axis of rotation of the spinning chamher.

A whirl field 101 is created due to the arrangement of the mouth 17 of the air inlet channel 16, as will be explained further on. This field compensates for the back-suction effect imparted to fibers by the air layer which travels with the lining 13 of the roller 8 within the zone of the separating edge, and the air stream with the separated fibers l2 advancing towards the spinning chamber 2, moves through the middle of the inlet channel 18.

It will be seen that the lining 13 is formed, for instance, by the illustrated teeth or by needles the inclination of which towards the tangent of the circumference of the combing roller 8 is preferably within the range of 80-l 20, opposite to the direction of rotation of the roller 8. The arrangement of the body 1 is such as to allow the circumferential distance G around the roller 8 from the end of the combing zone 102 to the point where the combing roller 8 enters into the air stream in the doffing zone 10, to exceed the staple length of the fibers, and the circumferential distance H around the roller 8 up to the point where the combing roller 8 enters the air stream in the doffing area 10, i.e., from the mouth 17 into the separating edge 14, to be longer than the effective staple length of the fibers also.

The fibers of the sliver 3 are separated and loosened by the combing roller 8 which transmits them to the doffing zone 10 where they are doffed from the lining 13 by the effective centrifugal and aerodynamic forces. The air stream admitted through the channel 16 entrains and delivers the fibers 12 in loosened state through the inlet channel 18 into the spinning chamber 2 where they are twisted into a yarn 20 which is withdrawn by the

rollers

38, 39 and wound onto the bobbin 40.

According to the invention, an appropriate configuration of the dofiing zone 10 is provided along with suitable speed and streaming form in this area. so as to effect the trajectory of the fibers 12 leaving the lining 13 in order to assure slight scattering of the fibers 12 so that they may not strike against the wall 15 and the separating edge 14. This is obtained by assuring that the basic trajectory of the fibers does not touch the wall 15 and the edge 14, this condition being fulfilled'by practically all of the fibers 12 if the amount of scattering remains within the

limits

23, 24. In other words: On the basis of the determined trajectory of the fibers 12 a configuration is chosen for the wall 15, the walls of the channel 18 and the edge 14, that these walls and the edge 14 will be located outside the scattering limits 23 and 24. Only about 1% of stray fibers 12 will fall outside these

limits

23 and 24. The wall 15 need not have a general planar form and can be convex or concave, as shown for instance in FIG. 2 or 3.

Provided that the trajectory 21 of the fiber stream is directed to the center of the mouth 19 of the inlet channel 18, as shown in FIG. 3, the impingement of stray fibers 12 against the wall 15 and the separating edge 14 is reduced to a minimum. If the trajectory 21 is characterized by the feature that its tangent 37 at the point 36 parallels the direction of the inlet channel 18, or the axis thereof which is the connecting line of the centers of the cross-sectional heights of the channel 18, the fibers 12 are optimally oriented for entry into the inlet channel 18 and in consequence practically no fibers will strike the walls thereof.

. If a parallel stream airfield is created in the doffing area 10, as shown in FIG. 4, the basic trajectory of the fibers 21 is determined by the following equations:

wherein t time/parameter c mean coefficient of air resistance for fibers v, air stream velocity v, circumferential velocity of combing roller ln natural logarithm for the base 2.

This provides a true picture of the streaming effect upon v trajectories 21 of the fibers 12. The natural tendency of the fibers 12 in a calm environment is to move out in the direction of a tangent to the lining 13 at the release point 11 at which they become separated from the lining. The constant c for cotton fibers has been experimentally determined as being c 2 3 cm. Successful results have been obtained with doffing the fibers 12 even for air velocities below the circumferential velocity of the combing roller 8. In other words. for the velocity v 20 m/sec and the air velocity v,.= 16.3 m/sec, the basic trajectory of the cotton fibers 12 at the mouth 19 having a cross sectional height amounting to 12 mm has been so directed that it will be 1 mm from the center to the upper half of the cross section. This has been achieved for the angle magnitude A 20.

It has been found advantageous to choose the value of the angle A within the range of 20, as shown in FIG. 5, while the value of the angle A has been confirmed as being particularly beneficial. This value should be adjusted to the character of the fibers 12 and the particular lining 13 used on the roller 8.

It is of course well known that different types of linings 13 exist, such as a lining having sawtoothlike configurations, having needles or combs, and when different types of such linings are used, it has been found simple to choose the angle B larger than the angle A, and for the center angle D A B to exceed 50, preferably being within the range of 60 70. This elimi nates the effective possible manufacturing imprecisions of the lining 13 and decreases still further the number of impacts of stray fibers 12 against the separating edge 14. A very advantageous aid in correctly choosing the distance ofthe wall 15 from the lining 13 is represented by the condition that the distance L 1726 should be equal to or larger than the distance L 1719.

If a lining is used which readily releases the fibers 12, it has been found to be of advantage of arrange the air intake channel 16 in the vicinity of the releasing point 11, and the cross-section of the air intake channel 16 to be chosen so as to be less than the smallest crosssection of the doffing area 10, as shown in FIG. 6. This causes an air stream from the channel 16 to pass through the doffing area and to make itself felt at the initial doffing stages. By a suitable form of the trajectory 21 according to the above mentioned principles the impacting of fibers against the wall 15 can be prevented.

If, however, linings 13 are used which do not readily release the fibers 12, an air intake channel 16 according to FIG. 7 should preferably be used, having a decreased cross-section adjacent to the wall 15. This results in streaming of the airflow within the doffing area 10 in such a manner that the trajectory 21 at the initial stage comes close to the tangent 25 over a longer range, while the fibers 12 are more intensively effected by the stream which is parallel with the wall 15 only at a certain shorter distance from the wall 15.

The orifice plate 28 with the orifice 29 as shown in FIG. 8, can be shifted in the guide 30 in order to create a suitable streaming picture for different kinds of fibers l2 and for different types of linings 13. Depending upon the position of the orifice 29, the fibers leaving the lining 13 are affected by an intensive air stream at a greater or shorter distance from the releasing point 11.

The embodiment illustrated in FIG. 9 represents a further possibility of affecting the streaming picture within the doffing area 10 by means of lateral air streams from the intake openings 32. The air streaming through these openings 32 can be either forced from an outer source of compressed air, or can be admitted by suction, for instance if the chamber 2 operates on the suction principle. This arrangement helps to maintain the stream of fibers 12 out of contact with the'wall 15. It is, therefore, preferred where linings 13 are used which readily release fibers and where the roller 8 rotates at high speeds.

The stream of fibers 12 can also be maintained out of contact with the edge 14, if as shown in FIG. 10 air streams are discharged from the doffing area 10 by discharge openings 33. The air discharged through these openings should be drawn away by suction, for instance by means of an external subatmospheric pressure source.

The embodiment in FIG. 11 represents an arrange ment of the doffing area 10 which is simple from the viewpoint of manufacture, the doffing area being formed by means of an insert 35 within the running channel 34. This latter channel has a continuously decreasing cross-section and can be readily produced from a casting or a pressure die casting.

In FIGS. 13 and 14 the air penetrates into the doffing area 10 through the channel 16 due to a sudden change of cross-sections, in the form ofa turbulent stream the whirling surface of which draws in the environmental air into which it is discharged, i.e., substantially from the zone where the bottom and the wall of the doffing area 10 converge, opposite the uncovered part of the combing roller 8 when a whirl field 101 is produced. Behind the mouth 17 of the bottom 100 the air stream makes its suction action felt up to the vicinity of the aforementioned wall of the doffing area 10 opposite the uncovered part of the combing roller 8, under the influence of the whirl field 101. This results in a deflection of the air stream which causes the back-suction effect, exerted upon the fibers 12 in the direction towards the lining 18 in the region of the separating edge 14, to be so counteracted that the loose separated fibers 12 are thrown into this air stream by centrifugal force through the surface air layer which travels around and with the roller 8. As a result, the fiber stream moves then with the air stream through the center of the inlet channel 18 without striking against the edge 14 or against the walls bounding the channel 18, and also without striking the wall 15. In the narrowing channel 18 the fiber stream accelerates, resulting in gradual straightening of the separated fibers 12 before the latter enter into the spinning chamber.

The volume of air entering into the spinning chamber 2 via the channel 18 amounts to 1 3 l/sec, while the necessary air streaming velocity due to the effect of the subatmospheric pressure source creates negative pressure of 100 250 mm water column. The air velocity gradually increases from the separating edge 14 to the point where the channel 18 discharges into the chamber 2.

The channel 16 can be shifted axially with respect to the center of the width of the combing roller 8, in order to limit axial deviations of the stream of separated fibers caused by structural features in connection with the orientation of the inlet channel 18, or in order to compensate for a possible trend of the fibers to be carried to one side in case the lining 13 should be of the type having helically wound combing instrumentalities, of the type shown in FIG. 14.

The illustrations in FIGS. 1-13 represent plane sections through the doffing area 10 which is substantially perpendicular to the axis of rotation of the combing roller. The form of the cross section at the doffing area can be arbitrary, within certain limits, so that it may be oblong, square, trapezoidal, elliptical or the like.

The present invention is based upon an experimental analysis of the trend of the fibers in their movement as they leave the lining 13, and also upon an extensive study of the scattering of the fibers as they have been released from the lining, all conducted with respect to different types of combing roller linings. The trajectory of fibers entering the parallel stream of streaming air under a skew angle was determined theoretically while the trajectory and the scattering of fibers around it was studied under conditions of very high fiber delivery rate to existing doffing areas, using different alternative solutions.

It will be understood that each of the elements described above, or two or more together, may also find a useful application of other types of constructions differing from the types described above.

While the invention has been illustrated and described as embodied in the ringless spinning of fibers, it is not intended to be limited to the details shown, since various modifications and structural changes may be made witout departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. In a ringless spinning machine, a combination comprising a housing having a hollow; a combing roller mounted in said hollow for rotation and having a covering which defines with a wall bounding said hollow a fiber channel and a doffing zone having an outlet and a separating edge at said outlet adjacent said roller; a spinning chamber having an inlet; admitting means ineluding an inlet channel for admitting fibers to be combed into contact with said covering for combing by said roller during travel with the same in said channel; and means for effecting doffing of said fibers from said roller in said doffing zone in such a manner that said fibers travel in a centrifugal trajectory through said doffing zone toward said inlet, the magnitude of an angle A included between an imaginary tangent to said covering at the point where the fibers are doffed from said roller and the wall bounding said hollow opposite the covering being in the range of and an angle B being included between an imaginary line that passes through the axis of rotation of said roller and through said separating edge and another line normal to the axis of said inlet channel and passing through the axis of rotation of said roller, the sum of said angles A and B being at least equal to 50.

2. A combination as defined in claim 1, wherein said sum is between 60 and 70.

3. A combination as defined in claim 1, wherein the distance between imaginary lines passing through an upstream and a downstream end of said doffing zone in direction normal to said wall, is smaller than the distance between the point of intersection of said tangent with said wall and said imaginary line passing through said upstream end. i

4. A combination as defined in claim 1; further comprising an air channel communicating with said doffing zone adjacent to the release point of said fibers from said roller, said air channel having a diameter which is smaller than the smallest diamter of said doffing zone.

5. A combination as defined in claim 4, wherein the circumferential distance from an upstream end of said doffing zone to the region where said roller enters a stream of air flowing through said zone from said air channel, is greater than the effective staple length of fibers to be combed.

6. A combination as defined in claim 5, wherein the circumferential distance from said region to a downstream end of said zone is greater than the effective staple length of fibers to be combed.

7. A combination as defined in claim 6, wherein said air channel, doffing zone and an inlet for the spinning chamber of said machine are formed as successive cylindrical passages.

8. A combination as defined in claim 1; further comprising an air channel communicating with said zone and having a diameter smaller than the smallest diameter of said zone, and an outlet closely adjacent said wall.

9. A combination as defined in claim 1; and further comprising an insert of convergent cross-section accommodated in said doffing zone in the region where the fibers are released from said roller.

10. In a ringless spinning machine, a combination comprising a housing having a hollow; a combing roller mounted in said hollow for rotation and having a covering which defines with a wall bounding said hollow a fiber channel and a doffing zone; admitting means for admitting fibers to be combed into contact with said covering for combing by said roller during travel with the same in said channel; and means for effecting doffing of said fibers from said roller in said doffing zone in such a manner that said fibers travel in scattered condition in said doffing zone, the magnitude of an angle A included between an imaginary tangent to said covering at the point where the fibers are doffed from said roller and the wall bounding said hollow opposite the covering being in the range of 0 20, and an adjustable orifice plate arranged in the region where fibers are released from said roller and having an orifice area which is smaller than the smallest diameter of said doffing zone.

11. In a ringless spinning machine, a combination comprising a housing having a hollow; a combing roller mountd in said hollow for rotation and having a covering which defines with a wall bounding said hollow a fiber channel and a doffing zone; admitting means for admitting fibers to be combined into contact with said covering for combing by said roller during travel with the same in said channel; and means for effecting doffing of said fibers from said roller in said doffing zone in such a manner that said fibers travel in scattered condition in said doffing zone, the magnitude of an angle A included between an imaginary tangent to said covering at the point where the fibers are doffed from said roller and the wall bounding said hollow opposite the covering being in the range of 0 20, and at least one air intake opening provided in said wall.

12. In a ringless spinning machine, a combination comprising a housing having a hollow; a combing roller mounted in said hollow for rotation and having a covering which defines with a wall bounding said hollow a fiber channel and a doffing zone; admitting means for admitting fibers to be combed into contact with said covering for combing by said roller during travel with the same in said channel; and means for effecting doffing of said fibers from said roller in said doffing zone in such a manner that said fibers travel in scattered condition in said doffing zone, the magnitude of an angle A included between an imaginary tangent to said covering at the point where the fibers are doffed from said roller and the wall bounding said hollow opposite the covering being in the range of and at least one air discharge opening in said wall.

13. In a ringless spinning machine, a combination comprising a housing having a hollow; a combing roller mounted in said hollow for rotation and having a covering which defines with a wall bounding said hollow a fiber channel and a doffing zone; admitting means for admitting fibers to be combed into contact with said covering for combing by said roller during travel with the same in said channel; and means for effecting doffing of said fibers from said roller in said doffing zone in such a manner that said fibers travel in scattered condition in said doffing zone, the magnitude of an angle A included between an imaginary tangent to said covering at the point where the fibers are doffed from said roller and the wall bounding said hollow opposite the covering being in the range of 020; and air intake and air discharge openings in said wall.

* l I I

Claims

1. In a ringless spinning machine, a combination comprising a housing having a hollow; a combing roller mounted in said hollow for rotation and having a covering which defines with a wall bounding said hollow a fiber channel and a doffing zone having an outlet and a separating edge at said outlet adjacent said roller; a spinning chamber having an inlet; admitting means including an inlet channel for admitting fibers to be combed into contact with said covering for combing by said roller during travel with the same in said channel; and means for effecting doffing of said fibers from said roller in said doffing zone in such a manner that said fibers travel in a centrifugal trajectory through said doffing zone toward said inlet, the magnitude of an angle A included between an imaginary tangent to said covering at the point where the fibers are doffed from said roller and the wall bounding said hollow opposite the covering being in the range of 0* - 20*, and an angle B being included between an imaginary line that passes through the axis of rotation of said roller and through said separating edge and another line normal to the axis of said inlet channel and passing through the axis of rotation of said roller, the sum of said angles A and B being at least equal to 50*.

2. A combination as defined in claim 1, wherein said sum is between 60* and 70*.

3. A combination as defined in claim 1, wherein the distance between imaginary lines passing through an upstream and a downstream end of said doffing zone in direction normal to said wall, is smaller than the distance between the point of intersection of said tangent with said wall and said imaginary line passing through said upstream end.

10. In a ringless spinning machine, a combination comprising a housing having a hollow; a combing roller mounted in said hollow for rotation and having a covering which defines with a wall bounding said hollow a fiber channel and a doffing zone; admitting means for admitting fibers to be combed into contact with said covering for combing by said roller during travel with the same in said channel; and means for effecting doffing of said fibers from said roller in said doffing zone in such a manner that said fibers travel in scattered condition in said doffing zone, the magnitude of an angle A included between an imaginary tangent to said covering at the point where the fibers are doffed from said roller and the wall bounding said hollow opposite the covering being in the range of 0* - 20*, and an adjustable orifice plate arranged in the region where fibers are released from said roller and having an orifice area which is smaller than the smallest diameter of said doffing zone.

11. In a ringless spinning machine, a combination comprising a housing having a hollow; a combing roller mountd in said hollow for rotation and having a covering which defines with a wall bounding said hollow a fiber channel and a doffing zone; admitting means for admitting fibers to be combined into contact with said covering for combing by said roller during travel with the same in said channel; and means for effecting doffing of said fibers from said roller in said doffing zone in such a manner that said fibers travel in scattered condition in said doffing zone, the magnitude of an angle A included between an imaginary tangent to said covering at the point where the fibers are doffed from said roller and the wall bounding said hollow opposite the covering being in the range of 0* - 20*, and at least one air intake opening provided in said wall.

12. In a ringless spinning machine, a combination comprising a housing having a hollow; a combing roller mounted in said hollow for rotation and having a covering which defines with a wall bounding said hollow a fiber channel and a doffing zone; admitting means for admitting fibers to be combed into contact with said covering for combing by said roller during travel with the same in said channel; and means for effecting doffing of said fibers from said roller in said doffing zone in such a manner that said fibers travel in scattered condition in said doffing zone, the magnitude of an angle A included between an imaginary tangent to said covering at the point where the fibers are doffed from said roller and the wall bounding said hollow opposite the covering being in the range of 0* - 20*; and at least one air discharge opening in said wall.

13. In a ringless spinning machine, a combination comprising a housing having a hollow; a combing roller mounted in said hollow for rotation and havIng a covering which defines with a wall bounding said hollow a fiber channel and a doffing zone; admitting means for admitting fibers to be combed into contact with said covering for combing by said roller during travel with the same in said channel; and means for effecting doffing of said fibers from said roller in said doffing zone in such a manner that said fibers travel in scattered condition in said doffing zone, the magnitude of an angle A included between an imaginary tangent to said covering at the point where the fibers are doffed from said roller and the wall bounding said hollow opposite the covering being in the range of 0* - 20*; and air intake and air discharge openings in said wall.