EP4669800A1

EP4669800A1 - Combing machine with means for controlling the speed of the breakaway rollers

Info

Publication number: EP4669800A1
Application number: EP24710502.6A
Authority: EP
Inventors: Luca SOLIANI; Paolo Vavassori
Original assignee: Marzoli Machines Textile SRL
Current assignee: Marzoli Machines Textile SRL
Priority date: 2023-02-20
Filing date: 2024-02-14
Publication date: 2025-12-31
Also published as: IT202300002808A1; WO2024176049A1

Abstract

A combing head for a combing machine for processing a web comprises a nipper (4), a pair of detaching rollers (20a', 20b') and a pair of auxiliary rollers (20a, 20b). The combing head comprises control means programmed or programmable to control the peripheral detaching roller speed (Vd') of the detaching rollers (20a', 20b') and the auxiliary peripheral speed (Vd) of the auxiliary rollers (20a, 20b), so that the detaching rollers (20a', 20b') nip a head end of the web length (W) with peripheral detaching roller speed (Vd') substantially equal to the maximum peripheral detaching roller speed (Vdmax').

Description

"COMBING MACHINE WITH MEANS FOR CONTROLLING THE SPEED

OF THE DETACHING ROLLERS"

DESCRIPTION

Field of the invention

[0001] The subject matter of the present invention relates to a combing machine of a spinning preparation line.

[0002] In a spinning preparation line, after the initial steps of opening and cleaning the fiber, a carding operation is performed by carding machines, after which the fiber takes the form of a sliver. After possible processing on a lap winder, in which several separate slivers are joined to obtain a lap, the sliver or web is combed by a combing machine in order to obtain a sliver in which the fibers are highly cleaned and parallelized.

Prior art

[0003] The basic combing operations, which in more recent machines follow one another at the rate of 550 to 600 strokes per minute, are: intermittent feeding of the web; combing, by means of a rotary comb, the head of the incoming piece with the nipper closed; overlapping and joining the head of the piece to the web already combed in the previous cycle, appropriately moved back, by means of detaching rollers during their rotation backwards; combing the tail of the piece by means of a straight nipper comb, with the nipper open; advancing the combed piece by means of the detaching rollers during the forward rotation thereof. [0004] The detaching rollers therefore have an alternating rotary movement. The moving members with alternating movement associated with the detaching rollers are of extreme importance in the design of the combing machine, as they are subjected to intense dynamic stresses, have considerable bulk and significantly affect the final cost of the combing machine .

[0005] Document EP-A1-1553219 describes a combing machine with unidirectional rotary motion of the detaching rollers. Further examples are illustrated in International Applications WO-A1-2019145802, W0-A1-

2019186307 and WO-A1-2020208454 in the name of the Applicant .

However, in such solutions, the quality of the web obtained is sometimes suboptimal, since, as it exits the detaching rollers with unidirectional continuous rotary motion, the web has fibers that are not fully parallelized at the edges, which tend to spill out of the combed web, creating problems in subsequent spinning steps.

[0006] Document WO-A1-2006012759 describes a combing machine equipped with a main roller with a perforated surface to obtain an air intake that contributes to the arrangement of the pieces. However, such solution is technologically complex, energy-consuming and does not effectively solve the problem of fibers spilling out from the edges.

[0007] A combing machine equipped with detaching rollers with unidirectional movement capable of solving the problems of the solution of WO-A1-2006012759, obtaining a high-quality combed web, is described in the Italian Patent Application No. 102022 000 008 438 in the name of the Applicant.

[0008] An additional issue related to newer combing machines relates to the optimization of the rotational speeds of the detaching rollers. These aspects, in fact, contribute to the formation, drawing and overlapping of the pieces, that is, they influence the final quality of the combed web that is obtained.

Object of the invention

[0009] The object of the present invention is to provide a combing machine with detaching rollers having unidirectional continuous rotary motion with variable speed that ensures a high production regime and a high qualitative level of the combed web.

[00010] This object is achieved by a combing machine constructed according to claim 1. The dependent claims describe further advantageous embodiments of the invention.

Description of the figures

[00011] The features and the advantages of the combing machine according to the present invention will become apparent from the following description, made by way of non-limiting example with reference to the accompanying figures, wherein:

Fig. 1 is a schematic view of a combing head of a combing machine, according to an embodiment of the present invention;

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

Fig. 11 shows the laws of motion of the detaching and auxiliary rollers, in which the x-axis shows the measurement in degrees of a complete rotation of the circular comb and the y-axis shows the peripheral speeds of the detaching and auxiliary rollers. Detailed description of the invention [00012] A combing machine according to the present invention comprises a fixed frame and a plurality of combing heads, for example aligned along a transverse axis, wherein each combing head comprises a nipper 4 supported by the fixed frame.

[00013] The nipper 4 comprises a lower jaw 6, an upper jaw 8, and a rectilinear comb 45 integral to the nipper 4, specifically to a nipper frame.

[00014] The nipper 4 also comprises a feeding roller 12 supported by the lower jaw 6 and intermittently rotatable to guide the web to be fed to the jaws 6, 8. [00015] The feeding roller 12 is equipped with an intermittent rotary motion that allows a web length W to be combed to emerge from the nipper 4.

[00016] The combing head comprises a pair 20' of superimposed detaching rollers 20a', 20b', preferably in pressure contact, provided with continuous rotary motion, with variable but not invertible speed, i.e., unidirectional. Preferably, the pair 20' of detaching rollers 20a', 20b' is positioned directly downstream of the nipper 4, for example in front of the nipper 4. The pair 20' of detaching rollers 20a', 20b' allows a web length W to emerge from the jaws 6, 8, detaching a piece from the web and carrying it downstream.

[00017] The detaching rollers 20a', 20b' have respective angular detaching roller speeds Wa', Wb' and equal peripheral detaching roller speeds Vd'. [00018] The combing head also comprises a pair 20 of auxiliary rollers 20a, 20b, placed downstream of the detaching rollers 20a' , 20b', comprising an upper auxiliary roller 20a and a lower auxiliary roller 20b, press-coupled with the upper auxiliary roller 20a and preferably rotationally driven.

[00019] Preferably, auxiliary rollers 20a, 20b are placed directly downstream of the detaching rollers 20a', 20b'.

[00020] The auxiliary rollers 20a, 20b have respective auxiliary angular speeds Wa, Wb and equal auxiliary peripheral speeds Vd.

[00021] Preferably, on the upstream side, between auxiliary rollers 20a, 20b an imaginary inlet plane Pl is defined tangent to the two auxiliary rollers 20a, 20b, and an inlet port 22 is identified between said inlet plane Pl and the side surfaces of the auxiliary rollers 20a, 20b. On the opposite side, i.e., on the downstream side, an outlet plane P2 is similarly defined and an outlet port 24 is identified.

[00022] The auxiliary rollers 20a, 20b have a continuous rotary motion, with non-invertable variable speed, i.e., unidirectional, that is such that they drive the piece S' exiting from the detaching rollers 20a', 20b' and carry it downstream, preferably from the inlet port 22 to the outlet port 24.

[00023] The combing head comprises a main device 26 having a main surface 28 that is movable, e.g., translating, preferably placed in front of the auxiliary rollers 20a, 20b, for example at the outlet port 24. In other words, the main device 26 is preferably positioned directly downstream of the auxiliary rollers 20a, 20b.

[00024] A piece exiting the auxiliary rollers 20a, 20b impacts against the movable main surface 28, in particular against an impact zone 29 of said main surface 28.

[00025] The main surface 28 of the main device 26 is provided with a main speed Va, particularly in the impact zone 29.

[00026] In one embodiment, the main device 26 comprises a main roller 30 equipped with unidirectional continuous rotary motion, with constant or variable speed, clockwise or counterclockwise, preferably arranged downstream of the auxiliary rollers 20a, 20b, e.g., in front thereof, facing the outlet port 24.

[00027] The main roller 30 has a side surface 30' that forms the main surface 28 of the main device 26.

[00028] According to one embodiment, the combing machine comprises electronic adjustment means suitable for adjusting 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 overlap between pieces.

[00029] According to one embodiment, the main surface 28, i.e., the side surface 30' of the main roller 30, is air-tight, in particular no suction holes or ports are provided.

[00030] Having defined an imaginary upper plane of the centers P5 passing through the rotation axes of the upper auxiliary roller 20a and the main roller 30, the upper plane of the centers P5 intersects the side surfaces of the upper auxiliary roller 20a and the main roller 30. The upper plane of the centers P5 defines an upper passage 34 between the upper auxiliary roller 20a and the main roller 30.

[00031] The combing head comprises a transfer device 40 to receive a web piece leaving the main surface 28 of the main device 26, i.e., the side surface 30' of the main roller 30. In particular, the piece is received in a transfer zone 42 of the transfer device 40.

[00032] The transfer device 40 is preferably movable, i.e., it has a predefined support speed Vs in the transfer zone 42. [00033] The transfer device 40 is preferentially engaged with the main surface 28 of the main device 26, for example it is tangent to the side surface 30' of the main roller 30 along an engagement line L. That is, in the transfer zone 42, the support speed Vs is equal to the main speed Va of the main surface 28.

[00034] Having defined an imaginary lower plane of the centers P4 passing through the rotation axes of the lower auxiliary roller 20b and the main roller 30, the lower plane of the centers P4 intersects the side surfaces of the lower auxiliary roller 20b and the main roller 30. The lower plane of the centers P4 defines a lower passage 32 between lower auxiliary roller 20b and the main roller 30.

[00035] A piece detached from the main surface 28 passes through the lower passage 32 to reach the transfer device 40.

[00036] Preferably, the transfer zone 42 is placed 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 of the main device 26, or the peripheral speed Vm of the main roller 30 in said engagement line L.

[00037] In one embodiment, the combing head 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.

[00038] In one embodiment, 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, for example by diverting its own trajectory .

[00039] The combing head comprises a circular comb 90, positioned below the nipper 4, provided with continuous rotary motion at constant or variable speed, always in the same direction.

[00040] The circular comb 90 has a combing arc for combing the web, and a directrix X passing through the rotation axis of the circular comb 90 and oriented in a radial direction with respect to the rotation axis of the circular comb 90.

[00041] The combing machine is provided with one or more electric motors and transmission members adapted to transfer motion from said at least one electric motor to the detaching rollers 20a', 20b', and to the auxiliary rollers 20a, 20b, and to the other components mentioned above.

[00042] The nipper 4 is provided with alternating forward and backward motion between an advanced limit position C, in which the jaws 6, 8 are proximal to the detaching rollers 20a', 20b', and a rearward limit position D, in which the jaws 6, 8 are distal from said detaching rollers 20a', 20b'. At the same time, the jaws 6, 8 are equipped with an alternating motion of opening and closing with a predefined nipper working speed.

[00043] When the nipper 4 is in the rearward limit position D, the combing arc of the circular comb 90 combs a head end of the web length W protruding from the jaws 6, 8.

[00044] Throughout the description, the rearward limit position D of the nipper 4 corresponds to the directrix X positioned at zero degrees, i.e., at a starting position of the circular comb 90.

[00045] At a first intermediate position A of the nipper 4, identified in the forward motion between the rearward limit position D and the advanced limit position C, the head end of the web length W is caught between the detaching rollers 20a', 20b', causing the detachment of a piece S' , which is carried from upstream to downstream by the continuous rotation of the detaching rollers 20a', 20b'.

[00046] The piece S' has a head length Hs' and a tail length Ts'. Preferably, with the head length Hs' nipped between the detaching rollers 20a', 20b', the tail length Ts' of the piece S' is combed by the rectilinear comb 45.

[00047] When returned to the rearward limit position D, the nipper 4 starts an additional forward motion. During the additional forward motion, the piece S' continues downstream and reaches the auxiliary rollers 20a, 20b and, upon reaching a second intermediate position B of the nipper 4, is nipped between the auxiliary rollers 20a, 20b.

[00048] Preferably, the second intermediate position B of the nipper 4 is different from the first intermediate position A along the forward motion.

[00049] The continuous rotation of the auxiliary rollers 20a, 20b results in the advancement of the piece S', in particular from the inlet port 22 toward the outlet port 24, until the head length Hs' impacts against the main surface 28 of the main device 26.

[00050] The ways in which the piece S' impacts against the main surface 28 are according to the peripheral speed Vd of the detaching rollers 20a, 20b. [00051] By virtue of the ratio between the peripheral speed Vd of the detaching rollers 20a, 20b and the main speed Va of the main device 26, the head length Hs' of the piece S' is arranged on the main surface 28 and is preferably directed toward the lower passage 32, while the tail length Ts' is arranged on the side surface of the upper auxiliary roller 20a. Between the head length Hs' and the tail length Ts' a bay R' is formed on the side of the upper passage 34, preferably between the upper auxiliary roller 20a and the main roller 30.

[00052] Progressively, from the head length Hs' towards the tail length Ts', the piece S' reaches the main surface 28 of the main device 26 and is transported thereby.

[00053] According to one embodiment, while it is driven, the piece S' is not subjected to any suction air current that makes it adhere to the main surface 28.

[00054] The head length Hs' of the piece S' begins to detach from the main surface 28 and heads toward the transfer zone 42 of the transfer device 40, for example by passing through the lower passage 32.

[00055] Progressively, the head length Hs' of the piece S' impacts against the transfer device 40, and the tail length Ts' detaches from the main surface 28.

[00056] At the same time, a further piece S'' is transferred from the detaching rollers 20a', 20b' to the auxiliary rollers 20a, 20b. The further piece S'' has a respective head length Hs'' and a tail length Ts''.

[00057] Like the piece S', the head length Hs'' of the further piece S'' heads toward the main device 26, that is, towards the main roller 30, impacting against the tail length Ts' of the piece S'. Meanwhile, the head length Hs' of the piece S' is driven by the transfer device 40.

[00058] Progressively, the head length Hs'' of the further piece S'' overlaps with the tail length Ts' of the piece S' by an overlapping length S*.

[00059] As the further piece S'' forms the bay R'', the head length Hs' of the piece S' continues to be driven by the transfer device 40.

[00060] Progressively, the overlapping length S* detaches from the main surface 28 and heads toward the transfer zone 42 of the transfer device 40, for example, by passing through the lower passage 32.

[00061] By overlapping the head length Hs'' of the further piece S'' to the tail length Ts'' of the piece S', the combed and continuous web, transported by the transfer device 40, is obtained.

[00062] Preferably, the head length Hs'' of the further piece S'' is placed underneath the tail length Ts'' of the piece S', i.e., it is arranged therebelow. Advantageously, this improves the transportability of the web on the transfer device, as the head length Hs'' of the further piece S'' does not tend to rise up from the tail length Ts' of the piece S'.

[00063] Preferably, the combed web transits between the main roller 30 and the transfer device 40, for example through the engagement line L, undergoing a compaction. Preferably, the combed web then passes between the compacting rollers 70a, 70b, and then exits the combing zone through the end rollers 80a, 80b.

[00064] According to one embodiment, for a plurality of combing heads or for all the combing heads, the combing machine comprises a single circular comb shaft for the movement of the respective circular combs, a single upper and a single lower detaching shaft for the detaching rollers, and a single auxiliary shaft for the auxiliary rollers.

[00065] Further details about the operation of the combing machine are contained in International Application WO-A1-2019186307 on behalf of the Applicant, the teaching of which is expressly incorporated herein.

[00066] The combing machine comprises control means programmed or programmable to control the detaching rollers 20a', 20b' , in particular to control the angular detaching rollers Wa', Wb' and the peripheral detaching roller speed Vd' and also to control the auxiliary rollers 20a, 20b, in particular to control the auxiliary angular speeds Wa, Wb and the auxiliary peripheral speed Vd.

[00067] For example, the control means comprise a control unit that is programmed or programmable to control the at least one electric motor.

[00068] The control modes of the detaching rollers 20a', 20b' and auxiliary rollers 20a, 20b are suitably adjustable according to the material and the average length of the piece S' to be processed.

Detaching rollers

[00069] The motion of the detaching rollers 20a', 20b' is divided into an acceleration step 100 and a deceleration step 110.

[00070] Preferably, the motion of the detaching rollers 20a', 20b' is sinusoidal or is curvilinear in lengths interspersed with one or more linear lengths, for example, having different slopes.

[00071] In the acceleration step 100 of the detaching rollers 20a', 20b', the peripheral detaching roller speed Vd' increases between a minimum peripheral detaching roller speed Vdmin' and a maximum peripheral detaching roller speed Vdmax'. [00072] During the acceleration step 100 of the detaching rollers 20a', 20b', the peripheral detaching roller speed Vd' has a variable trend. In particular, the acceleration step 100 of the detaching rollers 20a', 20b' is divided into two sub-steps 101, 102: in the first sub-step 101, from the minimum peripheral detaching roller speed Vdmin', the peripheral detaching roller speed Vd' increases with a curvilinear trend, for example with positive concavity; - in the second sub-step 102, the peripheral detaching roller speed Vd' increases with a curvilinear trend, for example with negative concavity, up to the maximum peripheral detaching roller speed Vdmax'.

[00073] In one embodiment, between the first sub-step 101 and the second sub-step 102 of the acceleration step 100, the peripheral detaching roller speed Vd' has an oblique tangent inflection point.

[00074] In a different embodiment, between the first sub-step 101 and the second sub-step 102 of the acceleration step 100 there is a linearly increasing segment, or several linearly increasing segments with different slopes.

[00075] At the end of the acceleration step 100, the detaching rollers 20a', 20b' reach the maximum point of the peripheral detaching roller speed Vd', that is, a horizontal tangent inflection point.

[00076] For example, for cotton and materials with similar characteristics, the maximum peripheral detaching roller speed Vdmax' is between 45 and 55 rpm, e.g. equal to about 50 rpm.

[00077] In the deceleration step 110 of the detaching rollers 20a', 20b', the peripheral detaching roller speed Vd' decreases from the maximum peripheral detaching roller speed Vdmax' down to the minimum peripheral detaching speed Vdmin'.

[00078] During the deceleration step 110 of the detaching rollers 20a', 20b', the peripheral detaching roller speed Vd' has a variable trend. In particular, the deceleration step 110 of the detaching rollers 20a', 20b' is divided into two sub-steps 111, 112: in the first sub-step 111, from the maximum peripheral detaching roller speed Vdmax', the peripheral detaching roller speed Vd' decreases with a curvilinear trend, such as with negative concavity;

- in the second sub-step 112, the peripheral detaching roller speed Vd' decreases with a curvilinear trend, such as with positive concavity, down to the minimum peripheral detaching roller speed Vdmin'.

[00079] In one embodiment, between the first sub-step 111 and the second sub-step 112 of the deceleration step 110, the peripheral detaching roller speed Vd' has an oblique tangent inflection point.

[00080] In a different embodiment, between the first sub-step 111 and the second sub-step 112 of the deceleration step 110 there is a linearly decreasing segment, or several linearly decreasing segments with different slopes.

[00081] At the end of the deceleration step 110, the detaching rollers 20a', 20b' reach the minimum point of the peripheral detaching roller speed Vd', i.e., a horizontal tangent inflection point.

[00082] For example, for cotton and materials with similar characteristics, the minimum peripheral detaching roller speed Vdmin' is between 20 and 30 rpm, e.g. equal to about 25 rpm.

[00083] In one embodiment, in a neighborhood Rm' of the minimum peripheral detaching roller speed Vdmin', the detaching rollers 20a', 20b' exhibit peripheral detaching roller speeds Vd' with substantially stable trends, barring amplitude changes ±5% in the minimum peripheral detaching roller speed Vdmin'.

[00084] The neighborhood Rm' of the minimum peripheral detaching roller speed Vdmin' is divided between the deceleration step 110 and the acceleration step 100. [00085] In other words, the neighborhood Rm' of the minimum peripheral detaching roller speed Vdmin' is a plateau region of the peripheral detaching roller speed Vd'.

[00086] The neighborhood Rm' of the minimum peripheral detaching roller speed Vdmin' corresponds to a circular comb rotation 90 of amplitude between 50 degrees and 130 degrees, preferably between 70 degrees and 120 degrees, e.g., about 100 degrees.

Auxiliary rollers

[00087] The motion of the auxiliary rollers 20a, 20b is either sinusoidal or is curvilinear in segments interspersed with one or more linear segments having different slopes.

[00088] The motion of the auxiliary rollers 20a, 20b is divided into an acceleration step 120 and a deceleration step 130.

[00089] In the acceleration step 120 of the auxiliary rollers 20a, 20b, the auxiliary peripheral speed Vd increases between a minimum auxiliary peripheral speed Vdmin and a maximum auxiliary peripheral speed Vdmax.

[00090] During the acceleration step 120 of the auxiliary rollers 20a, 20b, the auxiliary peripheral speed Vd has a variable trend. In particular, the acceleration step 120 of the auxiliary rollers 20a, 20b is divided into two sub-steps 121, 122:

- in the first sub-step 121, from the minimum auxiliary peripheral speed Vdmin, the auxiliary peripheral speed Vd increases with a curvilinear trend, for example with positive concavity;

- in the second sub-step 122, the auxiliary peripheral speed Vd increases with a curvilinear trend, such as with negative concavity, up to the maximum auxiliary peripheral speed Vdmax.

[00091] In one embodiment, between the first sub-step 121 and the second sub-step 122 of the acceleration step 120, the auxiliary peripheral speed Vd has an oblique tangent inflection point.

[00092] In a different embodiment, between the first sub-step 121 and the second sub-step 122 of the acceleration step 120 there is a linearly increasing segment, or several linearly increasing segments with different slopes.

[00093] At the end of the acceleration step 120, the auxiliary rollers 20a, 20b, reach the maximum point of the auxiliary peripheral speed Vd, i.e., a horizontal tangent inflection point.

[00094] For example, for cotton and materials with similar characteristics, the maximum auxiliary peripheral speed Vdmax is between 35 and 45 rpm, e.g., equal to about 50 rpm.

[00095] In the deceleration step 130 of the auxiliary rollers 20a, 20b, the auxiliary peripheral speed Vd decreases between the maximum auxiliary peripheral speed Vdmax and the minimum auxiliary peripheral speed Vdmin.

[00096] During the deceleration speed 130 of the auxiliary rollers 20a, 20b, the auxiliary peripheral speed Vd has a variable trend. In particular, the deceleration step 130 of the auxiliary rollers 20a, 20b is divided into two sub-steps 131, 132:

- in the first sub-step 131, from the maximum auxiliary peripheral speed Vdmax, the auxiliary peripheral speed Vd decreases with a curvilinear trend, for example with negative concavity;

- in the second sub-step 132, the auxiliary peripheral speed Vd decreases with a curvilinear trend, for example with positive concavity, down to the minimum auxiliary peripheral speed Vdmin.

[00097] In one embodiment, between the first sub-step 131 and the second sub-step 132 of the deceleration step 130, the auxiliary peripheral speed Vd has an oblique tangent inflection point.

[00098] In one embodiment, between the first sub-step 131 and the second sub-step 132 of the deceleration step 130 there is either a linearly decreasing segment or several linearly decreasing segments with different slopes.

[00099] At the end of the deceleration step 130, i.e., the second sub-step 132, the auxiliary rollers 20a, 20b, reach the minimum point of the auxiliary peripheral speed Vd, i.e., a horizontal tangent inflection point.

[000100] For example, for cotton and materials with similar characteristics, the minimum auxiliary peripheral speed Vdmin is between 20 and 30 rpm, for example equal to about 25 rpm.

[000101] In one embodiment, in a neighborhood Rm of the minimum auxiliary peripheral speed Vdmin, the auxiliary rollers 20a, 20b exhibit substantially constant auxiliary peripheral speed Vd and a notably stable trend, barring amplitude changes ±5% of the minimum auxiliary peripheral speed Vdmin.

[000102] The neighborhood Rm of the minimum auxiliary peripheral speed Vdmin is divided between the deceleration step 130 and the acceleration step 120.

[000103] In other words, the neighborhood of the minimum auxiliary peripheral speed Vdmin is a plateau region of the auxiliary peripheral speed Vd.

[000104] The neighborhood Rm of the minimum auxiliary peripheral speed Vdmin corresponds to a rotation of the circular comb 90 of amplitude between 80 degrees and 160 degrees, preferably between 90 degrees and 150 degrees, e.g., about 130 degrees. Working steps of the nipper [000105] With the nipper 4 in the rearward limit position D, the detaching rollers 20a', 20b' have peripheral detaching roller speeds VdO' between 90% and 100%, of the minimum peripheral speed Vdmin', preferably between 95% and 100% (ratio Vdmin'/VdO' between 0.90 and 1, preferably between 0.95 and 1). For example, the detaching rollers 20a', 20b' have peripheral detaching roller speed Vd' within the minimum region Rm' of the peripheral detaching roller speed Vd'.

[000106] With the nipper 4 in the rearward limit position D, the peripheral detaching roller speed Vd' has an increasing trend, for example, the detaching rollers 20a', 20b' are in the acceleration step 100, for example in the first sub-step 101, or have, for example, peripheral detaching roller speeds Vd' increasing linearly.

[000107] With the nipper 4 in the rearward limit position D, the auxiliary rollers 20a, 20b have a predefined auxiliary peripheral speed Vdl within an amplitude range 90%-100% of the maximum auxiliary peripheral speed Vdmax, preferably between 95% and 100% (Vdl/Vdmax ratio between 0.9 and 1, preferably between 0.95 and 1).

[000108] During a first working step (step I), defined between the rearward limit position D and the first intermediate position A, the web length W is combed by the rectilinear comb 45. Having reached the first intermediate position A of the nipper 4, the head end of the web length W is nipped between the detaching rollers 20a', 20b'.

[000109] For example, for average lengths of pieces S' between 26 and 42 millimeters, the first intermediate position A of the nipper 4 corresponds to a first rotated position of the circular comb 90, in which the directrix X is in a position between 135 and 175 degrees, for example equal to about 155 degrees, relative to the starting position.

[000110] During the first working step (step I), the detaching rollers 20a' , 20b' go through the acceleration step 100.

[000111] The detaching rollers 20a', 20b' nip the head end of the web length W with a predefined nipping peripheral detaching roller speed Vd* within a range of Il of the maximum peripheral detaching roller speed Vdmax'. Such neighborhood II comprises the maximum peripheral detaching roller speed Vdmax' and the peripheral detaching roller speeds Vd' between 90% and 100% of the maximum peripheral detaching roller speed Vdmax', preferably between 95% and 100%.

[000112] For example, the neighborhood II is symmetrical with respect to the maximum peripheral detaching roller speed Vdmax.

[000113] In other words, the neighborhood II is defined in such a way that the ratio KI between the predefined nipping peripheral detaching roller speed Vd* and the maximum nipping peripheral detaching roller speed Vdmax' (Kl=Vd*/Vdmax') is between 0.9 and 1, preferably between 0.95 and 1.

[000114] In still other words, the detaching rollers 20a', 20b' nip the head end of the web length W substantially at the maximum peripheral detaching roller speed Vdmax'.

[000115] At the end of the first working step (step I), for example, at the end of the second sub-step 102 of the acceleration step 100 of the detaching rollers 20a', 20b', the auxiliary rollers 20a, 20b have a predefined auxiliary peripheral speed Vd2 within an amplitude range 90%-100% of the minimum auxiliary peripheral speed Vdmin, preferably 95%-100% (Vdmin/Vd2 ratio between 0.90 and 1, preferably 0.95 and 1).

[000116] During a second working step (step II), defined between the first intermediate position A and the advanced limit position C of the nipper 4, the piece S' is driven by the detaching rollers 20a', 20b' toward the auxiliary rollers 20a, 20b. At the beginning of the second working step (step II), the nipper 4 is still moving to the advanced limit position C. At the end of the second working step (step II), the nipper 4 is in the advanced limit position C.

[000117] By way of example, for average lengths of the piece S' between 26 and 42 millimeters, the advanced limit position C of the nipper 4 corresponds to second a rotated position of the circular comb 90 in which the directrix X is in a position between 205 and 225 degrees, for example equal to about 216 degrees, with respect to the starting position.

[000118] During the second working step (step II), the detaching rollers 20a', 20b' have decreasing peripheral detaching roller speed Vd', for example they are in the first sub-step 111, or they have, for example, linearly decreasing peripheral detaching roller speed Vd'.

[000119] Preferably, at the end of the second working step (step II), the detaching rollers 20a', 20b' are in the second sub-step 111, or have linearly decreasing peripheral detaching roller speed Vd'.

[000120] The auxiliary rollers 20a, 20b reach the minimum auxiliary peripheral speed Vdmin in the first working step (step I) or in the second working step

(step II) of the nipper 4, depending on the average length and material of the piece.

[000121] With the nipper 4 in the advanced limit position C, i.e., at the end of the second working step

(step II), the auxiliary rollers 20a, 20b have a predefined auxiliary peripheral speed Vd3 within an amplitude range 90%-100% of the minimum auxiliary peripheral speed Vdmin, preferably 95%-100% (Vdmin/Vd3 ratio between 0.90 and 1, preferably between 0.95 and 1)•

[000122] Preferably, with the nipper 4 in the advanced limit position C, the auxiliary rollers 20a, 20b have auxiliary peripheral speed Vd within the neighborhood Rm of the minimum auxiliary peripheral speed Vdmin.

[000123] During a third working step (step III) of the nipper 4, defined between the advanced limit position C and the rearward limit position D, the detachment of a piece S' occurs. The head length Hs' of the piece S' is driven by the detaching rollers 20a', 20b'. At the end of the third working step (step III), the nipper 4 is in the rearward limit position D. In addition, at the end of the third working step (step III), the piece S' is still moving, preferably it is proximal to the auxiliary rollers 20a, 20b.

[000124] In the third working step (step III), the detaching rollers 20a', 20b' have decreasing peripheral detaching roller speed Vd', for example they are in the second sub-step 112.

[000125] During the third working step (step III), the auxiliary rollers 20a, 20b have increasing auxiliary peripheral speed Vd. At the end of the third working step (step III), the auxiliary rollers 20a, 20b have a predefined auxiliary peripheral speed Vdl within an amplitude range 90%-100% of the maximum auxiliary peripheral speed Vdmax, preferably 95%-100% (Vdk/Vdmax ratio between 0.90 and 1, preferably between 0.95 and 1)•

[000126] At the end of the third working step (step III), the detaching rollers 20a', 20b' have peripheral detaching roller speed VdO' between 90% and 100% of the minimum peripheral detaching roller speed Vdmin', preferably between 95% and 100% (ratio Vdmin'/VdO' between 0.90 and 1, preferably 0.95 and 1). For example, the detaching rollers 20a', 20b' have peripheral detaching roller speed Vd' within the minimum region Rm' of the peripheral detaching roller speed Vd'.

[000127] At the end of the third working step (step III), an additional working cycle begins to process the further piece S''.

[000128] In other words, at the end of the third working step (step III), the working cycle described for the piece S' is repeated for the further piece S''. [000129] In still other words, the fourth working step (step IV) for the piece S' (described below), occurs simultaneously with the first working step (step I) for the further piece S''.

[000130] During a fourth working step (step IV) of the nipper 4, defined between the rearward limit position D and the second intermediate position B, the piece S' is nipped between the detaching rollers 20a', 20b' and is moving toward the auxiliary rollers 20a, 20b. At the end of the fourth working step (step IV), the head length Hs' of the piece S' is nipped by the auxiliary rollers 20a, 20b.

[000131] In one embodiment, between the first intermediate position A and the second intermediate position B of the nipper 4, the circular comb 90 makes a rotation with an amplitude between 120 degrees and 180 degrees, preferably between 140 degrees and 160 degrees, for example equal to about 145 degrees. [000132] Preferably, at the beginning of the fourth working step (step IV), the detaching rollers 20a', 20b' have peripheral detaching roller speed Vd' within the neighborhood Rm' of the minimum peripheral detaching roller speed Vdmin'. Preferably, the detaching rollers 20a', 20b' have increasing speed, e.g., they are in the first sub-step 101, or they have linearly increasing peripheral detaching roller speed Vd'.

[000133] Preferably, at the end of the fourth working step (step IV), the detaching rollers 20a', 20b' have peripheral detaching roller speed Vd' within the neighborhood Rm' of the minimum peripheral detaching roller speed Vdmin'.

[000134] For example, at the end of the fourth working step (step IV), the auxiliary rollers 20a, 20b nip the head length Hs' of the piece S', and the detaching rollers 20a', 20b' have increasing peripheral detaching roller speed Vd', for example, with positive concavity. [000135] With the nipper 4 in the second intermediate position B, i.e., at the end of the fourth working step (step IV), the auxiliary rollers 20a, 20b nip the head length Hs' of the piece S' with a predefined auxiliary peripheral speed Vd** within a neighborhood 12 of the maximum auxiliary peripheral speed Vdmax. Such neighborhood 12 comprises the maximum auxiliary peripheral speed Vdmax and the peripheral detaching roller speeds Vd between 90% and 100% of the maximum auxiliary peripheral speed Vdmax, preferably between 95% and 100%.

[000136] For example, the neighborhood 12 is symmetrical with respect to the maximum auxiliary peripheral speed Vdmax.

[000137] In other words, the neighborhood 12 is defined in such a way that the ratio K2 between the predefined auxiliary peripheral speed Vd** and the maximum auxiliary peripheral speed Vdmax (K2= Vd**/ Vdmax) is between 0.9 and 1, preferably between 0.95 and 1.

[000138] In still other words, the head length Hs' of the piece S' is nipped between the auxiliary rollers 20a, 20b substantially at maximum auxiliary peripheral speed Vdmax.

[000139] The auxiliary rollers 20a, 20b reach the maximum auxiliary peripheral speed Vdmax in the fourth working step (step IV) or the first working step (step II) of the nipper 4, depending on the average length and the material of the piece.

[000140] As an example, for average lengths of the piece S' between 26 and 42 millimeters, the second intermediate position B of the nipper 4 corresponds to a rotated position of the circular comb 90, in which the directrix X is in a position between -10 degrees (i.e., 350 degrees, step IV) and 30 degrees (step I), for example, equal to about 9 degrees, relative to the starting position.

[000141] Having passed the fourth working step (step IV), the detaching rollers 20a', 20b' have increasing peripheral detaching roller speed Vd', for example they are in the first sub-step 101, or they have linearly increasing peripheral detaching roller speed Vd'.

[000142] Having passed the fourth working step (step IV), the auxiliary rollers 20a, 20b have decreasing auxiliary peripheral speed Vd, for example they are in the first sub-step 131 or have linearly decreasing auxiliary peripheral speed Vd.

[000143] Innovatively, the combing machine according to the present invention meets the needs of the industry in that the detaching rollers have unidirectional motion, eliminating the kinematics required to achieve a reciprocating rolling motion. Advantageously, by virtue of the simplification of the kinematics, high working speeds are achievable.

[000144] Advantageously, the control means allow accurate control of the peripheral speeds of the auxiliary rollers and detaching rollers, which may be adjusted according to the material and length of the piece.

[000145] It is clear that a person skilled in the art, in order to satisfy current needs, could make modifications to the combing machine described above, said modifications all being contained within the scope of protection as defined in the following claims.

Claims

1. A combing head for a combing machine for processing a web, comprising: a nipper (4) configured to carry out a reciprocating motion, from which a web length (W) is intended to project;

- a pair of superimposed detaching rollers (20a', 20b') configured to carry out a unidirectional continuous rotary motion with peripheral detaching roller speed (Vd'), between which a piece (S') detached from the web length (W) is intended to transit; a pair of superimposed auxiliary rollers (20a, 20b) configured to carry out a unidirectional continuous rotary motion with auxiliary peripheral speed (Vd), between which the piece (S') exiting from the detaching rollers (20a', 20b') is intended to transit;

- control means programmed or programmable to: a) control the detaching rollers (20a', 20b') between an acceleration step (100), up to a maximum peripheral detaching roller speed (Vdmax'), and a deceleration step (110), up to a minimum peripheral detaching roller speed (Vdmin'); and b) control the auxiliary rollers (20a, 20b) between an acceleration step (120), up to a maximum auxiliary peripheral speed (Vdmax), and a deceleration step (130), up to a minimum auxiliary peripheral speed (Vdmin); wherein the combing machine is configured so that the detaching rollers (20a', 20b') nip a head end of the web length (W) with peripheral detaching roller speed (Vd*) between 90% and 100% of the maximum peripheral detaching roller speed (Vdmax').

2. A combing head according to claim 1, configured so that when the head end of the web length (W) is nipped between the detaching rollers (20a', 20b' ), the auxiliary rollers (20a, 20b) have auxiliary peripheral speed (Vd2) between 90% and 100% of the minimum auxiliary peripheral speed (Vdmin).

3. A combing head according to any one of the preceding claims, configured so that the auxiliary rollers (20a, 20b) nip a head length (Hs') of the piece (S') exiting from the detaching rollers (20a', 20b') with auxiliary peripheral speed (Vd**) between 90% and 100% of the maximum auxiliary peripheral speed (Vdmax).

4. A combing head according to claim 3, configured so that when the head length (Hs') of the piece (S') is nipped between the auxiliary rollers (20a, 20b), the detaching rollers (20a', 20b') have peripheral detaching roller speed (Vdl') between 90% and 100% of the minimum peripheral detaching roller speed (Vdmin').

5. A combing head according to any one of the preceding claims, configured so that when the detaching rollers (20a', 20b') are in the deceleration step (110), the auxiliary rollers (20a, 20b) are in the acceleration step (120).

6. A combing head according to any one of the preceding claims, configured so that when the auxiliary rollers (20a, 20b) are in the deceleration step (130), the detaching rollers (20a', 20b') are in the acceleration step (100).

7. A combing head according to any one of the preceding claims when dependent on claim 3, comprising a circular comb (90) configured to rotationally comb the web length (W) projecting from the nipper (4), wherein the combing head is configured so that:

- the head end of the web length (W) is nipped between the detaching rollers (20a', 20b') at a first intermediate position (A) of the nipper (4); the head length (Hs') of the piece (S') is nipped between the auxiliary rollers (20a, 20b) at a second intermediate position (B) of the nipper (4); the circular comb (90) performs a rotation between 120 degrees and 170 degrees between the first intermediate position (A) and the second intermediate position (B) of the nipper (4).

8. A combing head according to any one of the preceding claims, configured so that when the nipper (4) is in an advanced limit position (C) in which the nipper (4) is proximal to the detaching rollers (20a', 20b'), the auxiliary rollers (20a, 20b) have auxiliary peripheral speed (Vd3) between 90% and 100% of the minimum auxiliary peripheral speed (Vdmin).

9. A combing head according to any one of the preceding claims, configured so that when the nipper (4) is in an advanced limit position (C) in which the nipper (4) is proximal to the detaching rollers (20a', 20b'), the detaching rollers (20a', 20b') are in the deceleration step (110).

10. A combing head according to any one of the preceding claims, wherein the control means are programmed or programmable to control the peripheral detaching roller speed (Vd') and/or to control the auxiliary peripheral speed (Vd) with continuous sinusoidal or curvilinear pattern interspersed with straight stretches.