WO2019186307A1

WO2019186307A1 - Combing machine of a spinning preparation line and working method

Info

Publication number: WO2019186307A1
Application number: PCT/IB2019/051946
Authority: WO
Inventors: Girolamo Prandini; Luca SOLIANI
Original assignee: MARZOLI MACHINES TEXTILE S.r.l.
Priority date: 2018-03-30
Filing date: 2019-03-11
Publication date: 2019-10-03
Also published as: DE112019000041T5; CN112204178A; CH714998B1; JP2021517612A; JP7221982B2; IT201800004119A1; CN112204178B

Abstract

A combing machine is able to perform a working method which involves detaching a tuft (S') of web through a pair of detaching rollers (20a', 20b') in continuous rotation, transferring the tuft (S') to auxiliary rollers (20a, 20b), sending the tuft (S') through the auxiliary rollers (20a, 20b) to a main roller (30) having a peripheral speed lower than that of the auxiliary rollers, causing the tuft (S') to impact against the main roller (30) and make it pull thereby, detaching a further tuft (S''), sending said further tuft (S'') towards the main roller (30) so that a head section (Hs'') of the further tuft (S'') crosses a tail section (Ts') of the tuft (S'), forming a continuous combed web (W), making the combed web (W) emerge from an outlet passage (32; 112) and transferring the combed web (W) to a transfer device (40) so that, on the transfer device (40), the head section (Hs'') of the further tuft (S'') is crossed and placed under the tail section (Ts') of the tuft (S').

Description

"COMBING MACHINE OF A SPINNING PREPARATION LINE AND

WORKING METHOD"

DESCRIPTION

Field of the invention

[0001] The object of the present invention is a combing machine of a spinning preparation line.

[0002] In a spinning preparation line, after the initial steps of opening and cleaning the fiber, carding is performed by carding machines, following which the fiber is in the form of a sliver.

[0003] After a possible processing on a lap winder, in which several separate slivers are joined to obtain a lap, the web or sliver is combed by a combing machine in order to obtain a sliver in which the fibers are highly parallelized and clean.

Prior art

[0004] The basic combing operations, which in more recent machines follow one another at the rate of 500 550 strokes per minute, are:

- intermittently feeding the web;

- combing, by means of a rotary comb, the head of the incoming tuft, with the nipper closed;

overlapping and joining the tuft head to the web already combed in the previous cycle, appropriately moved back, by detaching rollers during their rotation backwards ;

- combing the tail of the tuft using a straight nipper comb, with open nipper;

advancing the combed tuft by the detaching rollers during their forward rotation.

[0005] The detaching rollers therefore have an alternating rotary motion. The moving members of the detaching rollers, which, starting from an electric motor, control the detaching rollers and which allow the alternating movement, are one of the most problematic parts of the design and production of a combing machine.

[0006] These members must in fact withstand intense dynamic stresses, as they are subjected to repeated stops and restarts. As the speed of the machine increases, the speed of rotation increases proportionally in one direction and in the other of the detaching rollers. The dynamic stresses therefore become increasingly burdensome .

[0007] These members also have a considerable bulk and account for at least 30% to 40% of the final cost of the combing machine.

[0008] There are patent documents illustrating solutions of combing machines with unidirectional rotary movement of the detaching rollers. Let's consider, for example, document EP-A1-1553219. [0009] However, the Applicant, replicating for experimental purposes the solution illustrated in document EP-A1- 1553219, was able to ascertain that the result of the combing is not satisfactory from the point of view of the quality of the sliver obtained.

[0010] A further embodiment of a combing machine with detaching rollers having unidirectional motion is described in the Italian patent application No. 102018000001987, on behalf of the Applicant.

[0011] Lastly, there are further solutions of combing machines in which the detaching rollers are controlled by an electronically controlled electric motor to obtain the alternating rotary motion; in this case, the complicated mechanical movement members of said detaching rollers are not necessary.

[0012] However, these solutions have considerable drawbacks, mainly related to energy consumption, the heating of the electric motors, the duration of these motors and the response of the movement control.

Object of the invention

[0013] The object of the present invention is to provide a combing machine with detaching rollers having a continuous rotary motion (with constant or variable speed, but unidirectional), which is able to ensure a satisfactory qualitative level of the combed sliver. [0014] Such an object is achieved by a combing machine made according to claim 1. The dependent claims describe further advantageous embodiments of the invention.

Description of the figures

[0015] The features and the advantages of the combing machine according to the present invention will appear more clearly from the following description, made by way of an indicative and non-limiting example with reference to the accompanying figures, in which:

- figure 1 schematically shows a combing head of a combing machine, according to an embodiment of the present invention;

- figures 2 to 10 schematically show working steps of the combing head according to the present invention;

- figures 11 to 15 show further embodiments of the combing head according to the present invention.

Detailed description of the invention

First embodiment (figures 1 to 10)

[0016] A combing machine according to the present invention comprises a fixed frame and a plurality of combing heads, wherein each combing head comprises a nipper 4, supported by the fixed frame.

[0017] The nipper 4 comprises a lower jaw 6, an upper j aw 8 and a rectilinear comb 10, generally integral with the lower jaw 6. [0018] Moreover, the nipper 4 comprises a feeding roller 12, which can be rotated on command in an intermittent manner, supported by the lower jaw 6.

[0019] The combing head further comprises, downstream of the nipper 4, at least one pair of detaching rollers.

[0020] For example, preferably, immediately downstream of the nipper 4, in front of this, there is a pair 20' of detaching rollers 20a', 20b', superimposed, preferably in pressure contact, provided with continuous rotary motion (with constant or variable, but not invertible speed) , such as to drag a stretch of web protruding from the jaws, detach a tuft from the web and bring it downstream.

[0021] According to this embodiment, downstream of the pair 20' of detaching rollers 20a', 20b^f there is a pair 20 of auxiliary rollers, comprising an upper auxiliary roller 20a and a lower auxiliary roller 20b, generally coupled by pressure with the upper auxiliary roller 20a and preferably driven in rotation thereby.

[0022] Between the auxiliary rollers 20a, 20b, on the upstream side, having defined an imaginary inlet plane PI tangential to the two auxiliary rollers 20a, 20b, an inlet port 22 is identified between said inlet plane PI and the side surfaces of the auxiliary rollers 20a, 20b.

On the opposite side, i.e. on the downstream side, having likewise defined an outlet plane P2, an outlet port 24 is instead identified.

[0023] The auxiliary rollers 20a, 20b have a continuous rotary motion (with constant or variable but not reversible speed) , such as to drag a stretch of web provided by the detaching rollers 20a', 20b', detach a tuft from the web and bring it from the inlet port 22 towards the outlet port 24.

[0024] Said auxiliary rollers 20a, 20b have the same peripheral speed Vd and respective angular speeds Wa, Wb .

[0025] Moreover, the combing head comprises a main device

26, placed in front of the outlet port 24 of the auxiliary rollers 20a, 20b, provided with a movable main surface 28, for example translating, against which, and in particular against an impact zone 29 of said main surface 28, it impacts a tuft coming out of the auxiliary rollers 20a, 20b.

[0026] The main surface 28 is provided with a main speed Va, in particular in the impact zone 29.

[0027] For example, said main device 26 comprises a main roller 30, provided with continuous rotary motion (with constant or variable speed, but in any case unidirectional), in a clockwise or counter-clockwise direction, arranged downstream of the auxiliary rollers 20a, 20b, in front of these, facing the outlet port 24.

[0028] The main roller 30 has a side surface 30', which constitutes said main surface 28 of the main device 26.

[0029] The side surface 30', i.e. the main surface 28, is air-tight. In other words, no suction holes or ports are provided on said surface.

[0030] The main roller 30 generally has a diameter greater than the diameter of the main detaching rollers 20a, 20b and a peripheral speed Vm, which corresponds to an angular speed Wm.

[0031] The peripheral speed Vm of the main roller 30 is lower than the peripheral speed Vs of the auxiliary rollers 20a, 20b.

[0032] For example, the peripheral speed Vm of the main roller is between 20 - 40% of the peripheral speed Vs of the auxiliary rollers, for example between 25 - 35%, for example between 28 and 32%, for example about 30%.

[0033] Preferably, having defined an imaginary third plane P3, tangent to the auxiliary rollers 20a, 20b and passing through the contact line therebetween, the rotation axis 30'' of the main roller 30 is arranged below or above the third plane P3, according to the main speed Va, i.e. the direction of rotation of the main roller 30 facing the outlet port 24.

[0034] For example, in the representation in figure 2, the direction of rotation of the main roller 30 facing the outlet port 24 is downwards and the axis of rotation 30" of said main roller 30 is located below the third plane

P3.

[0035] In other words, the third plane P3 defines an outlet direction of the tufts S' from the outlet port 24.

[0036] The combing head further comprises a transfer device 40 on which, as will be seen hereinafter, a web tuft is brought which leaves the main surface 28 of the main device 26, or the side surface 30' of said main roller 30; said tuft moves into a transfer zone 42 of said transfer device 40.

[0037] Preferably, the transfer device 40 is engaged with the main surface 28 of the main device 26; for example, said transfer device 40 is tangent to the side surface 30' of said main roller 30 along an engagement line L.

[0038] Preferably, said transfer device 40 is flat in a neighborhood of said engagement line L.

[0039] Preferably, moreover, said transfer zone 42 of the transfer device 40 is flat.

[0040] Having defined a lower plane of the imaginary centers P4 passing through the axis of rotation of the lower auxiliary roller 20b and of the main roller 30, said lower plane of the centres P4 intersects the side surfaces of the lower auxiliary roller 20b and of the main roller 30, defining a lower passage 32 crossed by the tuft which is detached from the main surface 28, i.e. from the side surface 30', to move onto the transfer device 40.

[0041] An imaginary upper plane of the centres P5 is also defined, passing through the rotation axis of the upper auxiliary roller 20a and of the main roller 30; said upper plane of the centres P5 intersects the side surfaces of the upper auxiliary roller 20a and of the main roller 30, defining an upper passage 34.

[0042] The lower passage 32, through which the tuft detached from the main surface 28, i.e. from the side surface 30', transits, in order to move to the transfer device 40, is narrower than the upper passage 34.

[0043] In other words, the tuft that is detached from the main surface 28, i.e. from the side surface 30', to move to the transfer device 40 crosses the narrower passage (defined outlet passage) between the two passages made by the lower auxiliary roller 20b and the upper auxiliary roller 20a with respect to the main surface 28 of the main device 26, i.e. the side surface 30'.

[0044] The transfer zone 42 is located in front of the lower passage 32, for example upstream of the engagement line L, with reference to the direction of the main speed

Va or of the peripheral speed Vm of the main roller 30 in said engagement line L.

[0045] Preferably, moreover, said transfer device 40 is movable, i.e. provided with a predefined support speed Vs in the engagement zone 42.

[0046] For example, the combing machine is provided with a conveyor belt 50 which completes a closed path, preferably outside the main roller 30, and which, for at least a portion, forms said transfer device 40.

[0047] The speed of the belt 50 in the engagement zone 42 corresponds to said support speed Vs and is according to the main speed Va or to the peripheral speed of the main roller 30 in the engagement line L.

[0048] For example, in the engagement line L, the belt 50 is tangent to the main surface 28 or to the side surface 30' of the main roller 30.

[0049] Preferably, the belt 50, in order to define its own closed path, is wound around at least one diverter roller, preferably a pair 60 of diverter rollers 60a, 60b, for example arranged below the auxiliary rollers 20a, 20b, and around a further roller 60c, preferably arranged downstream of the main roller 30.

[0050] Preferably, the combing head further comprises a pair 70 of pressure rollers 70a, 70b, press-coupled, between which the combed web W carried by the transfer device 40 transits to flatten and regularize the thickness .

[0051] Preferably, at least one 70b of said pressure rollers 70a, 70b coincides with the further roller 60c on which the belt 50 is wound.

[0052] Preferably, moreover, the combing head comprises a pair 80 of end rollers 80a, 80b, press-coupled, between which the web W transits, preferably after having been flattened and regularized, to exit the combing zone, and after having diverted its own trajectory.

[0053] Preferably, at least one 80b of said end rollers 80a, 80b coincides with the further roller 60c on which the belt 50 is wound.

[0054] Ultimately, according to the illustrated embodiment, the pressure roller 70a and the end roller 80a are external to the path of the belt 50 and are press-coupled with the further roller 60c on which said belt 50 is wound, defining an arcuate trajectory together.

[0055] The combing head further comprises a circular comb 90, generally arranged below the nipper 4, provided with continuous rotary motion, at a constant or variable speed, always in the same direction.

[0056] The combing machine is provided with one or more electric motors and with a plurality of transmission members adapted to transfer the motion from said at least one electric motor to the components mentioned above.

[0057] In particular, the nipper has a forward and backward movement and the jaws have an opening and closing movement with a predefined working speed.

[0058] Moreover, the nipper 4 is provided with alternating forward and backward motion between an advanced limit position, in which the jaws 6, 8 are proximal to the detaching rollers 20a', 20b' and a rearward limit position, in which said jaws 6, 8 are distal to said detaching rollers 20a', 20b'.

[0059] At the same time, the jaws 6, 8 are provided with an alternating opening and closing motion, while the feeding roller 12 is provided with an intermittent rotary motion which allows a section of web to be released from the nipper .

[0060] When the nipper is in the advanced limit position, a combing sector of the circular comb combs the head of the web section protruding from the jaws and said head is taken between the detaching rollers 20a', 20b', causing the tearing of a tuft S', which is carried from upstream to downstream by the rotation of the rollers 20a', 20b' and transferred to the auxiliary rollers 20a, 20b (figure 2) .

[0061] For the tuft S', a head section Hs ' and a tail section Ts^f are defined. The tail section Ts^f of the tuft S' is combed by the straight comb 10.

[0062] The continuous rotation of the auxiliary rollers 20a, 20b with speed Vd causes the tuft S' to advance from the inlet port 22 towards the outlet port 24, until the head section Hs ' is impacted against the main surface 28 of the main device 26 or against the side surface 30' of the main roller 30 (figure 3) .

[0063] By virtue of the ratio between the peripheral speed

Vd of the detaching rollers 20a, 20b, on which the mode with which the tuft S' impacts against the main surface 28 depends, and the main speed Va, the head section Hs ' of the tuft S' is arranged on the main surface 28, or on the side surface 30' of the main roller 30, and directed towards the narrower passage, i.e. the lower passage 32, while the tail section Ts' is arranged on the side surface of the upper auxiliary roller 20a. Between the head section Hs ' and the tail section Ts', a bay R' is formed, between the upper auxiliary roller 20a and the main roller 30, that is, on the side of the wider passage, i.e. of the upper passage 34 (figure 4) .

[0064] Progressively, from the head section towards the tail section, the tuft S' moves on the main surface 28 of the main device 26, or on the side surface 30' of the main roller 30 (figure 5) and is carried thereby.

[0065] During the dragging, the tuft S' is not subjected to any current of suction air that makes it adhere to the main surface 28.

[0066] The head section Hs of the tuft S' begins to detach from the main surface 28, or from the side surface 30' of the main roller 30, passing through the lower passage 32 and heading towards the transfer zone 42 of the transfer device 40 (figure 6) .

[0067] Progressively, the tuft S' impacts with the head section Hs ' against the transfer device 40 and progressively the tail section Ts' is detached from the main surface 28, or from the side surface 30' of the main roller 30, while a further tuft S'' is transferred to the auxiliary rollers 20a, 20b by the detaching rollers 20a', 20b' ( figure 7 ) .

[0068] The further tuft S'' has a respective head section Hs ' ' and a respective tail section Ts''. Meanwhile, the head section Hs of the tuft S' is driven by the transfer device 40.

[0069] Like the tuft S', the head section Hs ' ' of the further tuft S'' is directed towards the main device 26, that is, towards the main roller 30, impacting against the tail section Ts' of the tuft S' (figure 8) . The head section Hs of the tuft S' continues to be driven by the transfer device 40.

[0070] The head section Hs ' ' of the further tuft S'' crosses the tail section Ts' of the tuft S', by an overlapping section S* (figure 9) . The head section Hs of the tuft S' continues to be dragged by the transfer device 40, while the further tuft S'^f forms the bay R' ' .

[0071] Progressively, the overlapping section S* detaches from the main surface 28, or from the side surface 30' of the main roller 30, and, crossing the narrower passage, i.e. the lower passage 32, moves towards the transfer zone 42 of the transfer device 40.

[0072] By overlapping the head section Hs ' ' of the further tuft S'' to the tail section Ts' of the tuft S', the combed and continuous sliver W is formed, carried by the transfer device 40.

[0073] For the sake of clarity, it is noted that the head section Hs ' ' of the further tuft S'' crosses the tail section Ts' of the tuft S', but is underneath thereto, that is, it is arranged below this, as is clear for the combed web W passing on the transfer device. Advantageously, this improves the transportability of the sliver on the transfer device, since the head section Hs ' ' of the further tuft S' ' does not tend to rise from the tail section Ts' of the tuft S'.

[0074] Preferably, the combed web W first passes between the main roller 30 and the transfer device 40, through the engagement line L, undergoing a first compaction.

[0075] Subsequently, preferably, the combed web W passes between the compacting rollers 70a, 70b, to then exit from the combing zone through the end rollers 80a, 80b. [0076] According to a preferred embodiment, the combing machine according to the present invention comprises a plurality of combing heads, for example aligned along a transverse axis, moved by a single circular comb shaft for the respective circular combs, a single upper detaching shaft and a single lower detaching shaft for the detaching rollers, and likewise for the auxiliary rollers .

Second embodiment (figure 11)

[0077] According to a further embodiment, which substantially follows what described above, the transfer device 40 is engaged with the main surface 28 of the main device 26 by an arcuate engagement portion Ai, for example by an arcuate portion of the side surface 30' of the main roller 30, defined in cooperation with a transfer roller 200.

[0078] For example, the path of the belt 50 of the transfer device 40 is defined by said transfer roller 200.

[0079] In this embodiment, the tuft S', and thus the combed web, does not detach from the main surface 28 to move, unsupported, towards the transfer device 40, but detaches from the main surface 28 only at the end of the arcuate engagement portion Ai, when it is already supported by the transfer device 40.

Third embodiment (figure 12) [0080] According to a further embodiment, which substantially follows what described above, the main device 26 comprises a main belt 100 movable along a closed path, facing the outlet port 24 of the auxiliary rollers 20a, 20b.

[0081] For example, the path of the main belt 100 is defined by a lower main roller 102 and an upper main roller 104, on which the main belt 100 is wound.

[0082] The main belt 100 has an outer surface which, in a stretch in front of the outlet port 24, forms said main surface 28 of the main device 26, against which the tuft coming from the auxiliary rollers 20a, 20b impacts.

[0083] A portion of the main surface 28 forms said impact zone 29.

[0084] The main surface 28 is air-tight, i.e. no holes or gaps are provided for a suction current intended to hold the tuft carried by said main surface.

Fourth embodiment (figure 13)

[0085] According to a further embodiment, which substantially follows what described above, the combing head 1 comprises an outlet roller 110, arranged downstream of the impact zone 29 between the tuft S' and the main surface 28 of the main device 26.

[0086] The imaginary outlet plane P5 is defined, passing through the rotation axis of the outlet roller 110 and of the main roller 30. Said outlet plane P5 intersects the side surfaces of the outlet roller 110 and of the main roller 30, defining an outlet passage 112 crossed by the tuft S' to continue on the transfer device 40.

[0087] The outlet passage 112 is narrower than the lower passage 32 formed by the lower auxiliary roller 20b with the main roller 30, as well as the upper passage 34 formed by the upper auxiliary roller 20a with the main roller 30.

[0088] Preferably, the transfer device 40 is engaged with the main surface 28 of the main device 26 by an arcuate engagement portion Ai, for example by an arcuate portion of the side surface 30' of the main roller 30, defined in cooperation with said outlet roller 110.

[0089] For example, the path of the belt 50 of the transfer device 40 is defined also by the outlet roller 110.

[0090] In this embodiment, the tuft S' does not detach from the main surface 28 to move, unsupported, towards the transfer device 40, but detaches from the main surface 28 only at the end of the arcuate engagement portion Ai, when it is already supported by the transfer device 40. Fifth embodiment (figure 14)

[0091] According to a further embodiment, which substantially follows what described above, the transfer device 40 engages the main surface 28 only along said engagement line L and, crossed by the outlet passage 112, the tuft S' detaches from the main surface 28 and, not supported, it moves towards the transfer device 40.

Sixth embodiment (figure 15)

[0092] According to a further embodiment, which substantially follows what described above, the combing head comprises an auxiliary device 300 which transfers the tuft S' detached by the detaching rollers 20a', 20b^f to the main device 26.

[0093] In the embodiments described above, the auxiliary device 300 comprises said auxiliary rollers 20a, 20b.

[0094] In the embodiment in figure 15, the auxiliary device 300 instead comprises an upper auxiliary roller 20a and a lower auxiliary group 302, coupled with the upper auxiliary roller 20a, comprising an auxiliary belt 304 which runs along a closed path, defined for example by auxiliary diverters 306, 308, 310, such as cylinders, rollers, corner elements and the like.

[0095] For example, the upper auxiliary roller 20a is motorized and in pressure contact with the auxiliary belt 304, to cause the motion thereof.

[0096] The outer surface of the auxiliary belt 304, which carries the tuft S', forms an auxiliary surface 320 of the auxiliary device 300, having a translation speed Vd.

[0097] Between the side surface of the upper auxiliary roller 20a and the path of the auxiliary belt 304, the outlet plane P2 is defined and, consequently, the outlet port 24.

[0098] The secondary passage 32 is defined by the minimum distance of the auxiliary surface 320 from the main surface 28.

Further embodiments

[0099] According to a further embodiment, the pair 20 of auxiliary rollers 20a, 20b is placed directly downstream of the nipper 4, in front of this, and therefore perform the function of detaching rollers, as described above.

[00100] In this embodiment, the detachment of the tuft

S' is performed directly by the auxiliary rollers 20a, 20b, which then transfer the tuft S' from the inlet port 22 to the outlet port 24.

[00101] In a further embodiment, the direction of rotation of the main roller facing the outlet port is facing upwards and the axis of rotation of said main roller is located above the third plane.

[00102] In this embodiment, the upper auxiliary roller

20b is closer to the main surface 28 than the lower auxiliary roller 20a, the upper passage is narrower than the lower passage and the section passes through the upper passage.

[00103] According to a further embodiment, the combing machine comprises electronic adjustment means adapted to adjust the speed of the main surface 28, or the rotation speed of the main roller 30. Advantageously, by means of said speed control it is possible to adjust the amount of overlapping between the tufts.

[00104] According to a further embodiment, the position of the main surface 28, that is, the position of the axis of rotation 30'' of the main roller 30, is adjustable, preferably vertically and/or horizontally. Advantageously, this possibility of adjustment allows shorter fibers or longer fibers to be processed, according to the distance set with respect to the main detaching rollers.

[00105] According to a further embodiment, the combing head comprises an auxiliary device comprising a lower auxiliary roller and an upper auxiliary group, having preferably the structural and functional features described above.

[00106] According to a still further embodiment, the auxiliary device comprises an upper auxiliary group and a lower auxiliary group, preferably having the structural and functional features described above.

0

[00107] The embodiments described above are not to be considered exclusive; on the contrary, the features described for an embodiment may be combined, together or separately, with one or more of the features described for the other embodiments.

[00108] Innovatively, the combing machine according to the present invention meets the needs of the sector, in that the detaching rollers have unidirectional motion; this allows eliminating the kinematic mechanisms necessary to obtain a pilgrim process movement.

[00109] Advantageously, moreover, the combing machine according to the invention, precisely by virtue of the simplification of the aforementioned mechanisms, allows reaching high working speeds, for example of 700 strokes/minute .

[00110] It is clear that a man skilled in the art may make changes to the combing machine described above in order to meet incidental needs, all falling within the scope of protection defined in the following claims.

Claims

1. Combing head of a combing machine, comprising:

- an auxiliary device (300; 20a, 20b), having an outlet port (24) where a combed and web detached tuft (S' ) passes through, said auxiliary device being provided with at least one auxiliary surface (320) that transports said tuft (S' ) , said auxiliary surface having a continuous motion at a predefined speed (Vd) ;

- a main device (26) provided with a main surface (28) movable at a predetermined main speed (Va) lower than the speed (Vd) of the auxiliary surface (320), said main surface (28) being arranged so that said tuft (S') at the outlet of said outlet port (24) impacts against an impact zone (29) of said main surface (28) ;

a secondary passage (34; 32) defined by the minimum distance of the auxiliary surface (320) from the main surface (28);

- an outlet passage (32; 112) from which emerges said tuft (S' ) , narrower than, or equal to, said secondary passage (34; 32) .

2. Combing head according to claim 1, wherein the auxiliary device (300) comprises a pair (20) of auxiliary rollers (20a, 20b) .

3. Combing head according to claim 2, wherein the outlet passage (32) is defined between the main surface (28) and the lower auxiliary roller (20b) .

4. Combing head according to claim 1, wherein the auxiliary device (300) comprises an auxiliary roller (20a, 20b) and an auxiliary group (302) provided with an auxiliary belt (304) which runs along a closed path, wherein the outer surface of the auxiliary belt (304) constitutes said auxiliary surface (320) .

5. Combing head according to claim 1, wherein the auxiliary device (300) comprises an upper auxiliary group and a lower auxiliary group, wherein at least one of said auxiliary groups is provided with an auxiliary belt (304) which runs along a closed path, wherein the outer surface of the auxiliary belt (304) constitutes said auxiliary surface (320) .

6. Combing head according to any one of the preceding claims, wherein the outlet passage (112) is defined between the main surface (28) and an outlet roller (110) .

7. Combing head according to any one of the preceding claims, wherein, having defined an outlet direction of the tuft (S') from the outlet port (24), the impact zone (29) of the main surface (28) is arranged below or above said outlet direction, in accordance with the direction of motion of the contact surface (28) facing the outlet port (24 ) .

8. Combing head according to any one of the preceding claims, wherein said main device (26) comprises a main roller (30) provided with continuous rotary motion, at constant or variable speed, wherein a side surface (30') of the main roller (30) implements said main surface (28) .

9. Combing head according to claim 8, wherein the main roller (30) has a diameter greater than the diameter of the auxiliary rollers (20a, 20b) .

10. Combing head according to any one of claims 1 to 7, wherein the main device (26) comprises a main belt (100) movable along a closed path, having an outer surface, which in a portion facing the outlet port (24) implements said main surface (28) .

11. Combing head according to any one of the preceding claims, comprising a transfer device (40) for conveying a sliver composed of the crossing of a plurality of tufts (S' ) .

12. Combing head according to claim 11, wherein the transfer device (40) is engaged with the main surface (28) along an engagement line (L) .

13. Combing head according to claim 12, wherein the transfer device (40) is engaged with the main surface (28) along an arched engagement portion (Ai) .

14. Combing head according to any one of claims 11 to 13, wherein the transfer device (40) is movable at a predetermined support speed (Vs) .

15. Combing head according to any one of claims 11 to 14, wherein the transfer device (40) is a conveyor belt (50) .

16. Combing head according to claim 15, wherein the belt (50) completes a closed path outside the main device

(26) .

17. Combing head according to any one of the preceding claims, wherein the position of the main surface (28) is adjustable horizontally and/or vertically.

18. Combing head according to any one of the preceding claims, wherein the main speed (Va) of the main surface (28) is adjustable.

19. Combing head according to any one of the preceding claims, wherein the main surface (28) is impermeable to air.

20. Combing machine comprising a plurality of combing heads according to any one of the preceding claims, aligned along a transverse axis.

21. Working method of a combing head, comprising the steps of:

- detaching a tuft (S' ) of web by means of a pair of detaching rollers (20a^f , 20b' ) or auxiliary rollers (20a, 20b) in continuous rotation;

- optionally, transferring the tuft (S' ) from the detaching rollers (20a^f , 20b' ) to the auxiliary rollers (20a, 20b) or to an auxiliary device (300);

sending the tuft (S' ) through the auxiliary rollers (20a, 20b) or through the auxiliary device (300) to a main device (26) having a main surface (28) movable at a main speed (Va) lower than that (Vd) of the auxiliary rollers (20a, 20b) or of the auxiliary device

(300) ;

impacting the tuft (S' ) against an impact zone (29) of the main surface (28) and pulling it from said main surface (28);

- detaching an additional tuft ( S' '), sending said additional tuft (S' ' ) through said auxiliary rollers (20a, 20b) or said auxiliary device (300) towards the main surface (28), so that a head section (Hs^f ' ) of the additional tuft (S' ' ) crosses a tail section (Ts' ) of the tuft (S' ) , forming a continuous combed web (W) ;

- making the combed web (W) emerge from an outlet passage (32; 112);

transferring the combed web (W) to a transfer device (40) so that, on the transfer device (40), the head section (Hs^f ' ) of the additional tuft (S' ' ) is crossed and placed under the tail section (Ts' ) of the tuft (S' ) .

22. Working method according to claim 21, wherein, during the step of pulling the tuft (S' ) from the main surface (28), the tuft (S') is not subjected to any suction air current .