Needle loom for consolidating a web or a sheet of fibers, in particular non-woven, assembly comprising a web or a sheet of fibers and a needle loom of this kind and method for operating a needle loom or an assembly of this kind

Abstract

Needle loom for consolidating a web or a sheet of fibers, in particular of non-woven, assembly comprising a web or a sheet of fibers and a needle loom of this kind and method for operating a needle loom or an assembly of this kind Method for operating a needle loom comprising at least one needle board, in which a web or a sheet of fibers is passed in front of the needles which moves in a direction called feed or machine direction or MD, between two extreme positions in which the free ends of the needles have zero speed, and the at least one needle board and / or the needles are driven in a back and forth movement in a direction other than the feed direction, in particular in the direction perpendicular or substantially perpendicular to the plane of the web or the web, so that the free ends of the needles have,in a first interval extending in the sheet or the veil between an outer surface of the veil or the sheet of fibers and an extreme position, a first movement having a first speed profile in absolute value for a first duration, then in a second interval extending in the sheet or the veil between said one extreme position and said one outer surface, a second movement having a second speed profile in absolute value for a second duration, is characterized in that the maximum speed of the second profile is greater than the maximum speed of the first profile and / or the second duration is less than the first duration. Figure for the abstract: Fig.1,

Description

Title of the invention: Needle loom for consolidating a web or a sheet of fibers, in particular non-woven, assembly comprising a web or a sheet of fibers and a needle loom of this type and method for operating a needle loom or an assembly of this type

[0001] The present invention relates to a needling machine for consolidating by needling a web or a sheet of fibers, in particular of non-woven, comprising at least one needle board, in front of which the web or the sheet of fibers passes while moving in a so-called feed direction, or machine direction or MD, and drive means configured to give the at least one needle board and / or the needles a back and forth movement in a direction other than the feed direction, in particular in the direction perpendicular or substantially perpendicular to the plane of the web or the web, so that the needles are introduced into the web or the web in one direction, then in another direction, are extracted from the web or the sheet of fibers, as well as to a method for operating a needling machine of this kind.

[0002] It would be desirable to improve known needling machines, in particular to increase their production rate without harming the quality of the web or sheet leaving the needling machine or, at the same production rate, to improve the quality of the web or sheet leaving the needling machine.

[0003] According to one of its aspects, the present invention relates to an assembly forming a needling machine, comprising a web or a sheet of fibers, in particular of non-woven, which moves in a direction called feed or machine direction or MD and a needling machine comprising one or more needle boards having a respective needle field or needle fields arranged so as to pass into the web or the sheet of fibers, in particular of non-woven, which moves opposite the needles, the needling machine comprising drive means configured to impart to the needles, in a displacement interval of the free ends of the needles between two extreme high and low positions where the free ends of the needles have zero speed, a back and forth movement, so that the free ends of the needles have,in a first interval extending in the sheet or veil between an outer surface of the veil or sheet of fibers and an extreme position, a first movement having a first velocity profile in absolute value for a first duration, then in a second interval extending in, the sheet or the veil between said one extreme position and said one external surface, a second movement having a second speed profile in absolute value during a second duration, is characterized in that: - the maximum speed of the second profile is higher than the maximum speed of the first profile and / or the second duration is lower than the first duration.

[0004] The present invention also relates to a method for operating a needling machine comprising at least one needle board, in which: - a web or sheet of fibers is passed in front of the needles and moves in a direction called feed or machine direction or MD, between two extreme positions in which the free ends of the needles have zero speed, and - the at least one needle board and / or the needles are driven in a reciprocating motion in a direction other than the direction of advance, in particular in the direction perpendicular or substantially perpendicular to the plane of the web or the veil, so that the free ends of the needles have, in a first interval extending in the web or the veil between an outer surface of the veil or the fiber web and an extreme position, a first movement having a first speed profile in absolute value for a first duration, then in a second interval extending in the web or the veil between said one extreme position and said one outer surface, a second movement having a second speed profile in absolute value for a second duration, is characterized in that: - the maximum speed of the second profile is higher than the maximum speed of the first profile and / or the second duration is lower than the first duration.

[0005] According to another aspect of the invention, which constitutes in itself an invention independently of the preceding aspects of the invention, but which, favorably, can be implemented in combination therewith, the free ends of the needles have, in a third interval, or prior interval, extending outside the sheet or web between the other extreme position and said outer surface of the web or sheet, a third movement having a speed profile in absolute value for a third duration, and in a fourth interval, or subsequent interval, extending inside the sheet or web between said outer surface and said other extreme position, a fourth movement having a speed profile in absolute value for a fourth duration, and the maximum speed of the first profile is lower than at least one of the maximum speeds of the third and fourth profiles, in particular at each of them,and / or the first duration is greater than at least one of the third and fourth durations, in particular each of them.

[0006] Preferably, the maximum speed of the second profile is lower than at least one of the maximum speeds of the third and fourth profiles, in particular each of them, and / or the second duration is greater than at least one of the third and fourth durations, in particular each of them.

[0007] According to yet another of its aspects, the present invention relates to a needling machine comprising one or more needle boards having a respective needle field or needle fields arranged so as to pass through a web or a sheet of fibers, in particular non-woven, which moves in a so-called feed direction, or machine direction or MD, opposite the needles, the needling machine comprising drive means configured to impart to the needles, in an interval of movement of the free ends of the needles between two extreme upper and lower positions where the free ends of the needles have a zero speed, a back and forth movement, so that the free ends of the needles have, in a first forward interval extending between the middle position and an extreme position, a first movement having a first forward speed profile in absolute value during a first forward duration,then in a second return interval extending between said one extreme position and said middle position, a second return movement having a second return profile of speeds in absolute value during a second return duration, characterized in that: , - the maximum speed of the second return profile is different from the maximum speed of the first return profile, and / or the second return duration is different from the first outward duration.

[0008] According to an aspect independent of the above aspect, which constitutes in itself an invention independently of it, but which, favorably, can be implemented in combination with it, the free ends of the needles have, in a third outward interval, extending between the other extreme position and the middle position, a third outward movement having a speed profile in absolute value during a third outward duration, and in a fourth return interval, extending between said middle position and said other extreme position, a fourth return movement having a speed profile in absolute value during a fourth return duration, and the maximum speed of the first profile is different from at least one of the maximum speeds of the third and fourth profiles, in particular each of them, and / or the first duration is different from at least one of the third and fourth durations, in particular each of them.

[0009] Preferably, the maximum speed of the second profile is different from at least one of the maximum speeds of the third and fourth profiles, in particular each of them, and / or the second duration is different from at least one of the third and fourth durations, in particular each of them.

[0010] According to each of the different aspects of the invention, a higher production rate and / or a better quality of the consolidated web or sheet is thus obtained.

[0011] Indeed, the needles comprise barbs which, when the needles are introduced into a web or a sheet of fibers, cling to the fibers and draw the latter in such a way as to become entangled with the other fibers and thus achieve consolidation. The inventors of the present invention have understood that too rapid a movement of the needles inside the web or the sheet, in particular in the direction in which the barbs are arranged to cling to the fibers, has the effect that the barbs cut the fibers instead of clinging them, which is detrimental to the quality of the consolidation.

[0012] At the same time, this effect is less when extracting the needles from the web or the sheet, so that one can also move more quickly when ascending in the web or the sheet compared to descending. Thus, at equal cycle rate (ascent + descent), one obtains a better quality, or otherwise, for the same quality, one can increase the rate.

[0013] Preferably, the drive means are configured so that the movement in the displacement interval in one direction between the two extreme positions in one direction, for example from top to bottom, takes place during a so-called introduction duration, and that the movement in the displacement interval between the two extreme positions in the opposite direction, for example from bottom to top, takes place during a so-called extraction duration, and the so-called introduction duration is greater than the so-called extraction duration.

[0014] Preferably, the so-called introduction time is between 1.01 and 5.0 times the so-called extraction time, preferably between 1.05 and 3.0, even more preferably between 1.1 and 2.0.

[0015] Preferably, the needles reach, during the so-called introduction duration, a maximum introduction speed, and during the so-called extraction duration, a maximum extraction speed, and the maximum extraction speed is greater than the maximum introduction speed.

[0016] Preferably, the maximum introduction speed is reached while the free ends of the needles are outside the sheet or web.

[0017] Preferably, the maximum extraction speed is reached while the free ends of the needles are outside the sheet or web.

[0018] According to a preferred embodiment, the drive means comprise at least one rotary element, a rotation of which through 360° corresponds to a drive of the needles on a back and forth cycle, and the movement in the interval of displacement in one direction between the two extreme positions, for example from top to bottom, of the needles takes place over a range which extends between 0° and an angle AR of rotation strictly greater than 180°, and the movement in the displacement interval between the two extreme positions in the opposite direction, for example from bottom to top, takes place over a range which extends between the AR angle of rotation and 360°, in particular the AR angle of rotation is between 181° and 210°, in particular between 185 and 200°, preferably between 190° and 195°.

[0019] According to a preferred embodiment of the invention, over a back-and-forth cycle, in particular a 360° cycle, the speed of the ends of the needles goes from zero to a maximum introduction value over a first introduction start time, then remains constant over a second introduction time at constant speed, then decreases to zero over a third introduction end time, then goes from zero to a maximum extraction value over a fourth extraction start time, then remains constant over a fifth extraction time at constant speed, in particular smaller than the second introduction time at constant speed, then decreases over a sixth extraction end time.

[0020] According to a favorable embodiment, the movement of the hands is a movement following a rectilinear trajectory, in particular vertical, in particular from bottom to top.

[0021] According to another equally favorable embodiment, the movement of the hands comprises a vertical component and a horizontal component and is not along a rectilinear trajectory.

[0022] According to a first advantageous embodiment, the drive means comprise a crankshaft whose connecting rod is articulated to a cam which drives a rod secured to the needles following a linear back and forth movement.

[0023] According to another advantageous embodiment, the drive means comprise a crankshaft whose connecting rod is articulated to a connecting rod articulated to a rod secured to the needles, the axis of rotation of the connecting rod of the crankshaft being offset relative to the back and forth direction of the rod secured to the needles.

[0024] According to another favorable embodiment, the veil or sheet of fibers, in particular non-woven, has a thickness which is between 5 and 70% of the travel of the ends of the needles between the two extreme points, in particular less than 60%, preferably less than 50%, in particular less than 40%.

[0025] In particular, the sheet or veil of fibers, in particular non-woven, extends while being supported by a support table.

[0026] In particular, the sheet or veil extends between a support table and a stripper, and in particular the distance between the support table and the stripper corresponds substantially to the travel between the two extreme points.

[0027] Embodiments of the invention are described below with reference to the drawings given solely by way of example, in which:

[0028] [Fig.l] is a schematic representation of a needling machine according to a first embodiment of the invention,

[0029] [Fig.2] is a schematic representation of a needling machine according to another embodiment of the invention;

[0030] [Fig. 3] is a schematic representation of a needling machine according to yet another embodiment according to the invention;

[0031] [Fig. 4] is a graph showing, on a needle introduction-extraction cycle, on the one hand an example of a curve giving the displacement of the needles as a function of the angle of rotation of the rotary element of the needle drive means of a needling machine according to the invention, in particular according to one of the embodiments of FIGS. 1 to 3, and on the other hand, an example of a curve giving the displacement of the needles as a function of the angle of rotation of the rotary element of the needle drive means of a needling machine of the prior art (for example according to the embodiment of [Fig. 3] with a constant rotation speed of the motor M1), the two rotary elements respectively of the needling machine according to the invention and according to the prior art having the same constant rotation speed;

[0032] [Fig. 5] is a graph showing, on a needle introduction-extraction cycle, on the one hand an example of a curve of the needle speeds as a function of the angle of rotation of the rotary element of the needle drive means of a needling machine according to the invention, in particular according to one of the embodiments of FIGS. 1 to 3, and on the other hand, an example of a curve of the needle speeds as a function of the angle of rotation of the rotary element of the needle drive means of a needling machine of the prior art (for example according to the embodiment of [Fig. 3] with a constant rotation speed of the motor M1), the two rotary elements respectively of the needling machine according to the invention and according to the prior art having the same constant rotation speed;

[0033] [Fig. 6] is a graph showing, on a needle introduction-extraction cycle, on the one hand an example of a curve of the needle speeds as a function of the angle of rotation of the rotary element of the needle drive means of a needling machine according to the invention, in particular according to one of the embodiments of FIGS. 1 to 3, and on the other hand, an example of a curve of the needle speeds as a function of the angle of rotation of the rotary element of the needle drive means of a needling machine of the prior art, the rotary element of the needling machine according to the invention having a constant rotation speed higher (by 15%) than that of the rotary element of the needling machine of the prior art;

[0034] [Fig.7] represents a graph giving profiles of the speed as a function of the travel of the ends of the needles on a cycle P1-P0-P2-P0-P1 according to an embodiment of the invention; and

[0035] Figures 8 to 10 are schematic representations of still other embodiments of needling machines according to the invention.

[0036] In [Fig. 1], a first embodiment of a needling machine according to the invention is shown.

[0037] A needle beam 1 comprises, coming from its lower face 2, a field of needles 13 (a single needle is shown in the figure) which extend vertically. These needles are intended to pass downwards (introduction movement) through a web or sheet 20 of fibers which moves in front of them from left to right in the figure, this direction being called the machine direction or MD direction. The MD direction is horizontal here.

[0038] This beam 1 is integral at the lower end with a vertical column 3 which is mounted articulated, at its other end, to a cam 4 mounted to rotate relative to an axis 5 perpendicular to the plane of the figure (the axis extends in the direction CD, perpendicular to the direction MD and to the vertical direction).

[0039] The cam 4 is driven in rotation at constant speed by the connecting rod 7 of a crankshaft 6 driven by an engine ML

[0040] The cam has a shape, for example circular, with its axis 5 of rotation offset relative to the axis of the circle of the circular shape. The cam can, however, have any other shape, depending on the desired speed profile.

[0041] The travel of the needle ends takes place between the upper end points PI and lower end points P2, points where the needle ends change direction and thus have zero speed. The midpoint PO is located halfway between the two points PI and P2.

[0042] The sheet or veil to be consolidated extends between the two points P3 and P4 corresponding to the upper and lower outer surfaces of the veil or sheet. In particular, point P4 may be above the lower point P2, or below the lower point P2 or coincide with it.

[0043] The midpoint may be located outside the two points P3 and P4, or inside the two points P3 and P4, in particular strictly inside the interval [P3; P4],

[0044] In particular, it is possible to provide a support table whose upper surface corresponds to point P2 and a stripper pierced with holes through which the needles pass and preferably point PI is located above the stripper to thus ensure that any fiber carried by the needle during its rise is blocked by the stripper and remains under it.

[0045] According to another embodiment shown in [Fig.8], two oval or elliptical gears 21, 22 can be provided for transmission between the motor M1 and at least one of the connecting rods of the module of [Fig.3], these eccentric gears meshing one into the other so as to obtain a differentiated speed of the needles with a motor Ml which rotates at a constant speed. However, this same arrangement could also be used with a motor Ml not rotating at a constant speed and obtain a speed profile still according to the invention, the arrangement allowing in particular the obtaining of numerous speed profiles.

[0046] According to yet another embodiment shown in [Fig. 9], at least one oval or elliptical pulley can be provided, in particular as shown, two elliptical pulleys 23, 24 and a belt 25 for transmission between the motor M1 and one of the connecting rods of the module of [Fig. 3], these elliptical pulleys and belt making it possible to obtain a differentiated speed of the needles with a motor M1 which rotates at a constant speed. However, this same arrangement could also be used with a motor M1 not rotating at a constant speed and a speed profile still according to the invention obtained, the arrangement making it possible in particular to obtain numerous speed profiles.

[0047] According to yet another embodiment shown in [Fig. 10], it is possible to provide, for the transmission between the motor M1 and at least one of the connecting rods of the module of [Fig. 3], a so-called "Maltese cross" transmission, comprising a disc 26 driven in rotation along its central axis by the motor M1 and comprising a lug 27 which projects from the disc at a distance from the center and which cooperates with a rotating element 28 in the shape of a Maltese cross comprising, alternating at its periphery, sections 29 in arcs of a circle and rectangular slots 30, the lug 27 cooperating as it rotates alternately with the arcs of circles and the slots to thus obtain a differentiated speed of the needles with a motor M1 which rotates at a constant speed, the speed profile being a function of the shapes and relative positions of the arcs and the slots.However, this same arrangement could also be used with a motor M1 not rotating at constant speed and a speed profile still obtained according to the invention, the arrangement in particular allowing numerous speed profiles to be obtained.

[0048] In [Fig.2], another embodiment of a needling machine according to the invention is shown.

[0049] The connecting rod 7' of a crankshaft 6' is mounted articulated to a connecting rod 4' itself mounted articulated to a column 3' secured to a board or beam 1' with needles. The axis 10' of rotation of the crankshaft is offset, in the MD direction, relative to the direction 11' of back and forth movement of the column 3', this offset resulting in a lowering time of the needles slower than the raising time, thus obtaining over a 360° rotation cycle a curve as shown in Figures 4 to 6.

[0050] The travel of the needle ends takes place between the upper end points P'1 and P'2, the points where the needle ends change direction and thus have zero speed. The midpoint P'0 is located halfway between the two points P'1 and P'2.

[0051] The sheet or veil to be consolidated extends between the two points P'3 and P'4 corresponding to the upper and lower outer surfaces of the veil or sheet. In particular, the point P'4 may be above the lower point P'2, or below the lower point P'2 or coincide with it.

[0052] The midpoint may be located outside the two points P'3 and P'4, or inside the two points P'3 and P'4, in particular strictly inside the interval [P'3; P'4].

[0053] In particular, it is possible to provide a support table whose upper surface corresponds to point P'2 and a stripper pierced with holes through which the needles pass and preferably point P' 1 is located above the stripper to thus ensure that any fiber carried by the needle during its ascent is blocked by the stripper and remains under it.

[0054] In [Fig.3], another embodiment of the invention is shown.

[0055] The assembly of [Fig.3] is a conventional assembly for driving the needles using a crankshaft which drives two connecting rods meshing with each other to rotate in opposition to thereby transmit a vertical movement to the needles. The crankshaft is driven by a motor M1 which is rotated by rotation control means which vary its rotational speed as a function of time to thereby implement a needle speed profile according to the invention.

[0056] In [Fig. 4], there is shown, over a rotation cycle from 0° to 360° of the rotation axis of the crankshaft motor of each of the embodiments of figures 1 to 3, the displacement, measured in mm in the vertical direction, of the needles, as well as for the case of a crankshaft drive system of the prior art, which achieves symmetrical needle drive between the ascent and descent.

[0057] In [Fig.4], we see that for the needling machines according to the invention, the end of the downward stroke (40mm downwards, corresponding to the top of the “sinusoid” curve) takes place for an angle of 190°, 10° greater than the case (180°) of the needling machines of the prior art.

[0058] Thus, the descent of the needles (introduction into the nonwoven sheet or veil) is carried out over a part of the cycle (0°-190°) of 190°, which is greater than the part of the return cycle (withdrawal of the needles) (190°-360°), equal to 170°, by 10°. This difference could be smaller or larger, in particular between 1° and 30°, preferably between 1° and 20°. In the case of the needling machines of the prior art, this difference is zero or substantially zero (of the order of a few seconds of a degree, less than 1°).

[0059] In particular, a maximum speed of the end of the needles is reached, on the one hand during the descent of the needles and on the other hand during the ascent, in the case of the needling machines of the prior art, exactly at the median point PO or P'O, corresponding respectively to rotation angles of 90° and 270°, whereas according to the invention, this maximum speed is reached, during the descent cycle, before the median point, then during the ascent also before the point, corresponding respectively to rotation angles of 80° and 260°. As a result, the maximum speed of the ends of the needles is reached in the interval ]P1; P0[ during the descent and in the interval ]P2; P0[ during the ascent.Thus, the velocity profile in the interval [PI; PO] has a maximum velocity equal to that of the velocity profile in the interval [P2; PO] and the velocity profile in the interval [PO; P2] has a maximum velocity which is lower than those of both profiles [PI; PO] and [P2; PO], and in the particular case here, equal to that of the profile in the interval [PO; PI].

[0060] On the other hand, the arrangement of the drive means of the needling machine can be chosen to ensure that the profile of the speed of the needles comprises a plateau during introduction and / or a plateau during extraction, as shown in Figures 5 and 6.

[0061] In [Fig. 5], the shape of the curve giving the speed of the needles during a rotation cycle of the drive crankshaft is shown in the case of the needling machine of the invention, for example [Fig. 1] and in the case of a needling machine of the prior art (for example according to [Fig. 3] with a constant rotation speed of the motor M1), the two crankshafts rotating at the same constant rotation speed, which gives the same speed of the nonwoven production line.

[0062] Thus, the speed profile of the needling machine of [Fig.l] comprises a first region of increasing speed up to an angle of approximately 57°, then a second region where the speed is constant, between 57° and approximately 133°, then a third region between 133° and 190° of decreasing down to zero speed.

[0063] For the needle extraction cycle, between 190° and 360°, the speed profile of the needling machine of [Fig.l] includes a fourth region of increasing speed (in absolute value) up to an angle of approximately 257°, ​​then a fifth region where the speed is constant, between 257° and approximately 293°, then a sixth region between 293° and 360° of decreasing down to zero speed.

[0064] The speed on the plateau of the second region is lower than the speed (in absolute value) on the plateau of the fifth region. Furthermore, the plateau of the second region extends over a larger part of the cycle than the plateau of the fifth region, notably between 1.5 and 3 times larger, notably between 2 and 2.5 times larger.

[0065] Thus, during extraction, the speed is higher and the speed profile steeper than during introduction, whereas for the needling machine of the prior art, there is symmetry of the speed profile between introduction and extraction.

[0066] In [Fig. 5], the constant rotational speed of the crankshaft for the two embodiments, respectively of [Fig. 1] and of the prior art ([Fig. 3] with constant rotational speed of the engine M1), is identical, here equal to 1850 rpm. At the same time, the penetration speed in the second region is 14% lower than the maximum speed of the needling machine of the prior art, which results in a better quality of the final product obtained at the outlet of the needling machine, in particular a better appearance.

[0067] In [Fig. 6], the shape of the curve giving the speed of the needles during a rotation cycle of the drive crankshaft is shown in the case of the needling machine according to an embodiment of the invention, for example according to [Fig. 1], and in the case of a needling machine of the prior art (for example according to the assembly of [Fig. 3] with a motor M1 rotating at constant speed), the two crankshafts rotating at different rotation speeds, namely the crankshaft of the needling machine according to the invention rotating faster than that of the needling machine of the prior art.

[0068] The speed profile of the needling machine according to the invention of [Fig.6] comprises a first region of increase in speed up to an angle of approximately 57°, then a second region where the speed is constant, between 57° and approximately 133°, then a third region between 133° and 190° of decrease down to zero speed.

[0069] For the needle extraction cycle, between 190° and 360°, the speed profile of the needle machine according to the invention of [Fig.6] comprises a fourth region of increasing speed up to an angle of approximately 257°, ​​then a fifth region where the speed is constant, between 257° and approximately 293°, then a sixth region between 293° and 360° of decreasing down to zero speed.

[0070] The speed on the plate of the second region is lower than the speed on the plate of the fifth region. Furthermore, the plate of the second region extends over a larger part of the cycle than the plate of the fifth region, in particular between 1.5 and 3 times larger, in particular between 2 and 2.5 times larger.

[0071] Thus, during extraction, the speed is higher and the speed profile steeper than during introduction, whereas for the needling machine of the prior art, there is symmetry of the speed profile between introduction and extraction.

[0072] In [Fig.6], the constant rotational speed of the crankshaft of the embodiment of [Fig.3] is higher than that of the crankshaft of the prior art, namely 2130 rpm for the invention and 1850 rpm for the prior art.

[0073] At the same time, the penetration speed in the second region is equal to the maximum speed of the prior art needling machine during introduction.

[0074] Thus in Figures 5 and 6, the free ends of the needles have, in the first interval extending between the high end position PI and the middle position PO, a first movement having a first speed profile in absolute value, then in a second interval extending between the middle position PO and the other extreme low position P2, a second movement having a second speed profile in absolute value, then in a third interval extending between the extreme low position P2 and the middle position PO, a third movement having a third speed profile in absolute value, then in a fourth interval extending between the middle position PO and the extreme high position PI, a fourth movement having a fourth speed profile in absolute value, and the maximum speed of the second profile (namely the value of the speed on the first plate) is lower than at least one of the maximum speeds of the first,third and fourth profiles, namely respectively the speed of the first chainring, the speed of the second chainring and the speed of the second chainring.

[0075] Similarly, the duration of the first interval (from PI to PO), proportional to the angle variation, i.e. 95°, is equal to the duration of the second interval (from PO to P2) and these two durations are greater than that of the third interval (from P2 to PO), proportional to the angle variation, i.e. 85°, also equal to the duration of the fourth interval (from PO to PI).

[0076] This results, for the same product quality, in particular an equally good homogeneity of the non-woven, in a higher production rate.

[0077] As can be seen in Figures 4 to 6, for embodiments according to the invention, the time taken to introduce the needles (in the embodiments shown, this is the descent time, but it would also be possible, according to another embodiment, to position the needles under the sheet or the web and carry out the movement of introducing the needles by an upward movement of the needles, then a downward extraction), is greater than the extraction time, these times being, in Figures 4 to 6, proportional to the angular extent of the descent (190°) and ascent (170°) cycles.

[0078] In [Fig.7], another example of speed profiles (in absolute value) of the ends of the needles according to the invention is shown.

[0079] Thus, in [Fig.7], the speed profile starts from a zero speed at PI (when the needles are in one of the end positions, for example high, increasing rapidly to reach a plateau. From a point upstream of point PO, the speed decreases again rapidly to a point downstream of point PO and then is observed up to a point close to P2, upstream of the latter, point at from which the speed decreases until reaching 0 at point P2. After P2, the speed (in absolute value) increases again to reach a third level which is higher than the first level, which extends to a point close to PI, upstream of the latter, before then decreasing rapidly to 0 at point PI, the cycle then resuming.

[0080] Embodiments for needling machines with rectilinear trajectories have been described above. However, it is possible, without departing from the scope of protection of the present application, to apply the present invention also to so-called elliptical needling machines, the path of the needles of which has a non-rectilinear loop shape, in particular of elliptical or substantially elliptical shape, in particular a shape having two half elliptical curves, each of different eccentricity (due to the difference in speeds between the introduction movement and the extraction movement).

Claims

Claims

1. Assembly forming a needling machine, comprising a web or a sheet of fibers, in particular of non-woven, which moves in a direction called feed or machine direction or MD and a needling machine comprising one or more needle boards having a field of needles or respective needle fields arranged so as to pass into the web or the sheet of fibers, in particular of non-woven, which moves opposite the needles, the needling machine comprising drive means configured to impart to the needles, in a displacement interval of the free ends of the needles between two extreme upper and lower positions where the free ends of the needles have a vertical rectilinear back and forth movement, so that the free ends of the needles have, in a first interval extending in the sheet or the web between an external surface of the web or the sheet of fibers and an extreme position,a first movement having a first speed profile in absolute value for a first duration, then in a second interval extending in the sheet or veil between said one extreme position and said one outer surface, a second movement having a second speed profile in absolute value for a second duration, and the needles comprise barbs which, when the needles are introduced into a veil or sheet of fibers, cling to the fibers and drive the latter so as to become entangled with the other fibers and thus achieve consolidation, characterized in that:, - the maximum speed of the second profile is higher than the maximum speed of the first profile and / or the second duration is lower than the first duration.

2. Method for operating a needling machine comprising at least one needle board, in which: - a web or sheet of fibers is passed in front of the needles and moves in a direction called feed or machine direction or MD, between two extreme positions in which the free ends of the needles have zero speed, and

3. - the at least one needle board and / or the needles are driven in a vertical rectilinear reciprocating motion in a direction other than the direction of advance, in particular in the direction perpendicular or substantially perpendicular to the plane of the web or the veil, so that the free ends of the needles have, in a first interval extending in the web or the veil between an outer surface of the veil or the web of fibers and an extreme position, a first movement having a first speed profile in absolute value for a first duration, then in a second interval extending in the web or the veil between said one extreme position and said one outer surface, a second movement having a second speed profile in absolute value for a second duration and the needles comprising barbs which, when the needles are introduced into a web or a web of fibers,cling to the fibers and cause the latter to become entangled with the other fibers and thus achieve consolidation, characterized in that:, - the maximum speed of the second profile is higher than the maximum speed of the first profile and / or the second duration is lower than the first duration. Assembly according to claim 1 or method according to claim 2, characterized in that the free ends of the needles have, in a third interval, or prior interval, extending outside the sheet or web between the other extreme position and said outer surface of the web or sheet, a third movement having a speed profile in absolute value for a third duration, and in a fourth interval, or subsequent interval, extending inside the sheet or web between said outer surface and said other extreme position, a fourth movement having a speed profile in absolute value for a fourth duration, and the maximum speed of the first profile is lower than at least one of the maximum speeds of the third and fourth profiles, in particular at each of them, and / or the first duration is greater than at least one of the third and fourth durations, in particular each of them.

4. An assembly or method according to claim 3, characterized in that the maximum speed of the second profile is lower than at least one of the maximum speeds of the third and fourth profiles, in particular each of them, and / or the second duration is greater than at least one of the third and fourth durations, in particular each of them.

5. Needle loom comprising one or more needle boards having a respective needle field or needle fields arranged so as to pass through a web or a sheet of fibers, in particular non-woven, which moves in a so-called feed direction, or machine direction or MD, opposite the needles, the needling machine comprising drive means configured to impart to the needles, in an interval of movement of the free ends of the needles between two extreme upper and lower positions where the free ends of the needles have zero speed, a vertical rectilinear back and forth movement, so that the free ends of the needles have, in a first forward interval extending between a middle position and an extreme position, a first movement having a first forward speed profile in absolute value during a first forward duration,then in a second return interval extending between said one extreme position and said middle position, a second return movement having a second return profile of speeds in absolute value during a second return duration, and the needles comprise barbs which, when the needles are introduced into a web or a sheet of fibers, cling to the fibers and drive the latter so as to become entangled with the other fibers and thus achieve consolidation, characterized in that: - the maximum speed of the second return profile is different from the maximum speed of the first return profile, and / or the second return duration is different from the first outward duration.,

6. Needling machine according to claim 5, characterized in that the free ends of the needles have, in a third forward interval, extending between the other extreme position and the middle position, a third outward movement having a speed profile in absolute value during a third outward duration, and in a fourth return interval, extending between said middle position and said other extreme position, a fourth return movement having a speed profile in absolute value during a fourth return duration, and the maximum speed of the first profile is different from at least one of the maximum speeds of the third and fourth profiles, in particular each of them, and / or the first duration is different from at least one of the third and fourth durations, in particular each of them.

7. Needling machine according to claim 6, characterized in that the maximum speed of the second profile is different from at least one of the maximum speeds of the third and fourth profiles, in particular each of them, and / or the second duration is different from at least one of the third and fourth durations, in particular each of them.

8. Assembly according to one of claims 1, 3 or 4 or or method according to one of claims 2 to 4 or needling machine according to one of claims 5 to 7, characterized in that the drive means are configured so that the movement in the displacement interval in one direction between the two extreme positions in one direction, for example from top to bottom, takes place during a so-called introduction time, and that the movement in the displacement interval between the two extreme positions in the opposite direction, for example from bottom to top, takes place during a so-called extraction time, and the so-called introduction time is greater than the so-called extraction time.

9. Assembly or method or needling machine according to claim 8, characterized in that the so-called introduction time is between 1.01 and 5 times the so-called extraction time, preferably between 1.05 and 3.0, even more preferably between 1.1 and 2.

0.

10. Assembly or method or needling machine according to claim 8 or 9, characterized in that the needles reach, during the so-called introduction time, a maximum introduction speed, and during the so-called extraction time, a maximum extraction speed, and the maximum extraction speed is greater than the maximum introduction speed.

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