EP0690162A2 - Method of needling webs, apparatus suitable therefore and their use - Google Patents

Abstract

A continuous material (9) is needle punched by taking it over several needle rollers (1) which rotate with their axes (3) perpendicular to the material path. The material (9) covers part of the circumference of the needle rollers (1) and their speed relative to the material is set to obtain the required needling effect with adjustable longitudinal stretch. Also claimed is the arrangement where the needle rollers (1) rotate about their axes (3) and the axes (3) move along a circular path. <IMAGE>

Description

The present invention relates to a method for needling material webs, such as foils or nonwovens, and to a device adapted for carrying out the method.

Mechanical consolidation steps can be used in the manufacture and processing of nonwovens or laminates, usually using needles, air or water jets. Examples of such treatment steps are the pre-compression of nonwovens or the connection of several nonwoven layers to form a laminate. Such mechanical treatments are common and are e.g. in "Vliesstoffe", chapter Vliesverfestigung, pp. 122-129 (publisher: Lünenschloß / Albrecht, Georg Thieme Verlag (1982)).

In addition to the bonding of nonwovens, the use of needles has also become known in other processing steps for nonwovens.

From DE-Gbm-82-11,455 a machine for pre-consolidating a fleece is known, which is characterized by the use of a transport device in the form of belts with needles.

Furthermore, DE-AS-2,160,209 discloses a method for the heat fixing of nonwovens, in which the nonwoven to be treated is passed over a fixing roller covered with needles.

In these previously known methods and devices, the needles are only used to transport webs of material.

The use of a single rotating needle roller for needling material webs has already been described.

DE-A-2 530 872 describes a needle device which consists of a single roller equipped with felting needles and a support roller which is equipped with pressure-resistant but laterally deflectable support elements. Both rollers run against each other, the textile material is needled in the engagement area of the rollers with felting needles. When using needle rollers, it can be expected that the material web to be needled can be damaged under the drastic conditions of needling. In these devices, the needles radially projecting from the roller and rotating with the roller between the needle foot and the needle tip have different peripheral speeds. Therefore, the needle normally acts differently depending on the depth of penetration into the material web when the needle is in a material web moving at a constant speed.

A needling device is described in DE-C-38 22 652, in which a single needle roller describes a hypocycloid path, on the one hand about the axis of the needle roller and on the other hand about an axis of rotation parallel to the roller axis. With this device, only a low needling density, i.e. too few punctures per unit area.

In conventional needling, a needle bar moves up and down perpendicular to the direction of movement of the substrate to be needled. The needles enter and exit the respective substrate and perforate the material web; barbs in the needles cause individual fibers to devour. The maximum achievable production speeds of conventional needle machines so far are around 40 m / min and are mainly limited by the maximum achievable Frequency of the needle bar, the required needling density and the longitudinal distortion caused by the dwell time in the fleece.

It is an object of the present invention to provide a method for needling material webs, in which considerably higher production speeds can be achieved with the usual needling densities compared to conventional needling processes.

The present invention relates to a method for needling a material web, characterized in that the material web is guided at a predetermined speed over a plurality of needle rollers rotating about its longitudinal axis and arranged transversely to the direction of movement of the material web, the material web each covering part of the surface of the needle rollers, and wherein the peripheral speed of the needle rollers relative to the speed of the material web is set such that the desired degree of needling is obtained with adjustable longitudinal distortion.

“Material web” in the sense of the present description is to be understood to mean those flat structures whose structure is changed by the action of the needles of the needle roller; Examples of this are films or in particular textile fabrics, in particular nonwovens or combinations containing nonwovens and thus fabrics to be connected to form laminates.

"Needling" in the sense of the present description means a treatment of the aforementioned material webs by the needles of the needle roller, the structure of the material webs being changed by this treatment. Examples of needling steps are perforating, slitting foils or textile fabrics, and preferably mechanically engulfing or connecting the fibers of textile fabrics, such as nonwovens or laminates containing nonwovens. The needles can be smooth or barbed.

As already mentioned, at a predetermined speed of rotation of the needle roller, the needles projecting radially from the roller have different speeds along their radial extension. A material web located in the engagement area of the needle roller and moving at a predetermined speed thus experiences different deformations along its thickness, which result from the relative speed between the needle and the material web at this point.

Furthermore, the direction of movement of the material web changes during transport along a needle roller, as a result of which the relative speed between a needle and the material web also changes. Consequently, the forces acting on the material web at a specific location of the material web change during the transport of the material web along the needle roller.

The method according to the invention is based on the finding that the forces caused by the relative speed between the needle movement and the movement of the material web in the same material web are adjusted such that the desired needling effect is achieved.

In a preferred embodiment of the method according to the invention, the speed n of the _{needle rollers is} selected such that the peripheral speed v _{needle of} the needles at at least one point in the material web in the area between the needle foot and the needle tip and at a point in the area between the needle entry and exit corresponds to the speed v _{mat of} the material web.

The speed n of the _{needle rollers} is very particularly preferably selected such that the peripheral speed v _{needle of} the needles at at least one point in the material web in the area between the needle foot and the needle tip and in the middle between the needle entry and exit points of the speed v _{mat of} the material web corresponds.

In a further preferred embodiment of the method according to the invention, the speed n of the needle roller, the speed v _{mat of} the material _web and the wrap angle α of the material _{web around} the needle _{roller are} selected such that the vectorial difference between the peripheral speed v _{nspe of} the needle tips and the speed of the material _web v _mat at the location of the puncture of the needle into the material _web results in a rate of penetration of the needle v _rele , the direction of which is perpendicular to the direction of movement of the material _web at the location of the puncture of the needle into this material web.

The conditions when the needle emerges from the material web can of course be used in an analogous manner. In this case, the speed n of the needle roller, the speed v _{mat of} the material _web and the wrap angle a of the material _{web around} the needle _{roller are} chosen such that the vectorial difference between the peripheral speed v _{nspa of} the needle tips and the speed of the material _web v _mat at the point of the Exit of the needle from the material _web results in an exit speed of the needle v _rela , the direction of which is perpendicular to the direction of movement of the material web at the point of exit of the needle from this material web.

In a further particularly preferred embodiment of the method according to the invention, a plurality of needle rollers rotating about their longitudinal axis and having a radius r are guided in a circle with the radius R.

The material web is preferably guided such that it can come into contact with the needle rollers along the circular movement circumscribed by the needle rollers, approximately half the way.

This type of guidance of the needle rollers in the form of a planetary movement can easily cause the needle rollers to roll on the material web; thus kinematic compensation is the Different rolling speeds possible between the needle foot and the needle tip.

With the help of the planetary movement of the needle rollers, there are a number of design parameters that allow a favorable solution for longitudinal distortion, needle density and production speed. Due to the opposite movement of the axes of the needle rollers to the material web movement, it can be achieved, for example, that the needle rollers behave synchronously with the movement of the material web in spite of a higher peripheral speed than the speed of the material web during needle engagement.

Caused by the rolling motion of a needle roller in relation to the material web, the needle engages in the material web at different peripheral speeds depending on the immersion depth. These peripheral speeds should be adapted to the transport speed of the material web as far as possible. If there are too large differences between these two speeds, this can lead to longitudinal distortion or even damage to the material web. It is therefore preferred to have a penetration movement of the needle which is as perpendicular as possible to the direction of movement of the material web.

The method according to the invention offers the possibility, during a rolling, continuous needling process, of designing the relative speed between the movement of the needle and the movement of the material web, regardless of the depth of penetration of the needle into the material web, such that the difference between the web-oriented component of the movement of the needle and the Material web speed is minimized to zero.

In a particularly preferred embodiment of the method according to the invention, a plurality of needle rollers of radius r rotating about their longitudinal axes are guided in a circle of radius R, the direction of rotation of the Needle rollers run counter to the direction of rotation of the needle roller axes and the speed of the material web v _mat , the speed n of the needle rollers with radius r and the rotational speed N of the needle roller axes on the circular path with radius R are selected so that they correspond to the relationship (I) $${\text{v}}_{\text{mat}}\text{= 2 * π * r * n - 2 * π * (r + R) * N}$$

• Figur 1 stellt eine Vorrichtung zur Durchführung des erfindungsgemäßen Verfahrens im Querschnitt dar, welche ebenfalls ein Gegenstand der vorliegenden Erfindung ist.
• Figur 2 zeigt weitere Einzelheiten der Vorrichtung nach Figur 1.
• Figur 3 zeigt die Geschwindigkeitsverhältnisse beim Vernadeln mittels der Vorrichtung nach Figur 1.
• Figur 4 schließlich stellt den Einsatz der erfindungsgemäßen Vorrichtung beim Vernadeln vorverfestigter Vliesstoffe dar.

The invention is illustrated in more detail in FIGS. 1 to 4.

• Figure 1 shows a device for performing the method according to the invention in cross section, which is also an object of the present invention.
• FIG. 2 shows further details of the device according to FIG. 1.
• FIG. 3 shows the speed relationships when needling by means of the device according to FIG. 1.
• Figure 4 finally shows the use of the device according to the invention when needling pre-consolidated nonwovens.

The device according to FIG. 1 comprises a plurality of needle rollers (1) of radius r, which are operated at the speed n, and a plurality of backup rollers (2). Needles of length Δ r project from the needle rollers in the radial direction. Needle rollers (1) and back-up rollers (2) follow each other alternately, can each be rotated about their longitudinal axes (3, 4) and are in turn arranged in a circle. The needle rollers are guided at the speed N with the radius R. For this purpose, needle rollers (1) and backup rollers (2) are located on a carrier (5). Carrier (5) and the needle rollers (1) are each moved by different drives, not shown. The needle rollers are preferably moved via a gear drive. The material web (9) is guided at a speed v _mat along part of the surface of the circular arrangement of the needle and support rollers, preferably at the positions before the impact and after leaving the material web (9) of the device according to the invention there are deflection rollers (8).

FIG. 2 shows the arrangement of a needle roller (1) and a backup roller (2) according to FIG. 1 in detail. Furthermore, the preferred speed ratios in the moments of the puncture and the puncturing of the needles into the material web are shown in this figure. The needle roller (1) has a radius r and rotates at a speed n. Needles of the length Δ r protrude radially from the needle roller (1). The material web (9) moves along the support roller (2) and the needle roller (1) at the speed v _mat . Wrap angle α of the material web (9) around the needle roller (1) and contact angle β can be modified by changing the position of the support roller (2).

The wrap angle 2α is to be understood as the angle that the distance between the center point of the needle roller (1) and the point of impact of the material web (9) on the needle roller (1) and the distance between the center point of the needle roller (1) and the lifting point Enclose the material web (9) from the needle roller (1).

The contact angle 2β is to be understood as the angle which the distance between the center of the needle roller (1) and the point of impact of the material web (9) on the needle tips and the distance between the center of the needle roller (1) and the lifting point of the material web (9 ) from the needle tips.

The axis of rotation (3) of the needle roller (1) in turn moves around a circle with the radius R at the rotational speed N.

läßt sich bei vorgegebener Geschwindigkeit der Materialbahn v_mat und gewählter Umlaufdrehzahl N die bevorzugte Drehzahl der Nadelwalze n ermitteln; diese ergibt sich danach zu $${\text{n = (2 * π * (R + r) * N + v}}_{\text{mat}}\text{) / 2 * π * r}$$

From the relationship (I) shown above $${\text{v}}_{\text{mat}}\text{= 2 * π * r * n - 2 * π * (r + R) * N}$$

the preferred speed of the needle roller n can be determined at a predetermined speed of the material web v _mat and a selected rotational speed N; this arises afterwards $${\text{n = (2 * π * (R + r) * N + v}}_{\text{mat}}\text{) / 2 * π * r}$$

By changing different parameters, different needling densities or longitudinal distortions of the material webs can be achieved.

These parameters include, for example, radius R, diameter and number of needle rollers, wrap angle α or contact angle β, speeds n and N.

In a particularly preferred embodiment, eight needle rollers with a radius r 200 mm are used, which move in a circle of radius R of 800 mm. This arrangement is shown in FIG. 2 for a wrap angle 2α of 22.5 °.

At a speed of the material web of 100 m / min and a rotational speed N of 10 min 10¹, this corresponds to a needle roller speed n of 129.6 min⁻¹ according to the above relationship (II).

The resulting speed relationships at the single-needle and needle-out points can be seen from the vector diagrams also shown in FIG. The relative speeds v _rele and v _rela formed from the speed of the needle tip v _needle and the speed of the material _web v _mat can be derived from the vector diagrams and gives here 1030 mm / sec.

Since v _rele and v _rela are arranged perpendicular to the speed of the material _web in the variant of the method _{according to} the invention, this means that there is no relative advance or retardation of the needle at the needling and needling point, that is to say no delay. With a maximum wrap angle of 157.5 ° (three needle rollers and four support rollers in the wrap area) of the material web along the circle circumscribed by the needle rollers, this is 5.83 rollings of a needle roller in the material web engagement. With a needle pitch of 10 mm, this results in a needling density of 3.74 mm in the longitudinal direction of the material web.

If a longitudinal distortion is now desired, this is possible in the described case, for example, by a slight change in the speed n and / or N; however, this can also be achieved by changing the wrap angle α, for example by changing the radial position of the support rollers.

In FIG. 3 A / B, the vector diagram contained in FIG. 2 at the location of the needle insertion is shown in detail for two embodiments. From this it can be seen that the speed of the needle tip v _{nspe is} itself a relative movement, which is composed of the rotary movement of the _needle rollers n with the peripheral speed v _needle and the rotational speed N of the _needle roller axis with the peripheral speed v _pl . FIG. 3 shows the speed _{relationships} with the same speed of the material _web v _mat of 100 m / min and different speeds v _pl and v _nspe . In both variants shown, care was taken to ensure that the vectorial difference between the circumferential speed v _{nspe of} the needle tips and the speed of the material _web v _mat at the point of insertion of the needle into the material _web results in a penetration speed of the needle v _rele , the direction of which is perpendicular to the direction of movement the material web is at the point where the needle punctures this material web. The upper vector diagram in FIG. 3 shows the speed ratios when needling, where n = 179.58 min⁻¹ and N = 20 min⁻¹; the lower vector diagram in Figure 3 shows the speed ratios when needling, where n = 129.577 min77¹ and N 10 min⁻¹.

FIG. 4 shows the needling of a pre-consolidated nonwoven with the device according to the invention. A web of non-pre-consolidated nonwoven fabric (13) is fed from a conveyor belt (12) running between rollers (11) to a non-pre-consolidated nonwoven fabric (13) to a pre-consolidation device (14), for example a device in which pre-needling takes place by means of water jets. The material web (9) is then needled further in the device (15) according to the invention. In this, the material web (9) is guided in a semicircle along radially arranged and moving needle rollers (1) and support rollers (2), which in turn rotate about their axes and move with their axes in the opposite direction. When the material web is moving, it can of course be supported for the needling process from the outside by guide elements known per se, such as circulating belts. The needled nonwoven is then fed to a dryer and winder, not shown. Deflection pulleys (16, 17, 18) are respectively mounted between the pre-consolidation device (14) and the device (15) according to the invention, the deflection pulley (17) additionally containing a water suction device.

In the embodiment shown, the device according to the invention can be operated, for example, with the following setting:
Speed of the nonwoven: 100 m / min
Radius R + r of the nonwoven web along the device according to the invention: 1000 mm
Orbital rotation N: 20 min⁻¹ (corresponding to an external speed of 125.66 m / min)
Radius r of the needle rollers: 200 mm
Speed of the needle rollers n: 179.58 min⁻¹ (corresponding to an external speed of 225.67 m / min)
Needle length: 12 mm (corresponding to an external speed of the needle tip of 239.21 m / min).

Claims (16)

Method for needling a material web, characterized in that the material web is guided at a predetermined speed over a plurality of needle rollers rotating about its longitudinal axis and arranged transversely to the direction of movement of the material web, the material web each covering part of the surface of the needle rollers, and the peripheral speed of the Needle rollers are adjusted relative to the speed of the material web in such a way that the desired degree of needling is obtained with adjustable longitudinal distortion. Method for needling a material web according to claim 1, characterized in that the speed n of the _{needle rollers} is selected such that the peripheral speed v _{needle of} the needles at at least one location in the material web in the area between the needle foot and the needle tip and at a location in the area between the needle entry and exit the speed v _{mat of} the material web corresponds. Method for needling a material web according to claim 1, characterized in that the rotational speed n of the _{needle rollers} is selected such that the peripheral speed v _{needle of} the needles at at least one point in the material web in the area between the needle foot and the needle tip and in the middle between the needle - and exit point corresponds to the speed v _{mat of} the material web. Method for needling a material web according to claim 1, characterized in that the speed n of the needle roller, the speed v _{mat of} the material _web and the wrap angle α of the material _{web around} the needle _roller are selected such that the vectorial difference between the peripheral speed v _{nspe of} the needle tips and the speed of the material _web v _mat at the point of insertion of the needle into the material _web results in a penetration speed of the needle v _rele , the direction of which is perpendicular the direction of movement of the material web at the point where the needle punctures this material web. Method for needling a material web according to claim 1, characterized in that the speed n of the needle roller, the speed v _{mat of} the material _web and the wrap angle α of the material _{web around} the needle _roller are selected such that the vectorial difference between the peripheral speed v _{nspa of} the needle tips and the speed of the material _web v _mat at the point of exit of the needle from the material _web results in an exit speed of the needle v _rela , the direction of which is perpendicular to the direction of movement of the material web at the location of the exit of the needle from this material web. Method for needling a material web according to claim 1, characterized in that a plurality of needle rollers rotating about their longitudinal axis and having a radius r are guided in a circle with the radius R. Method for needling a material web according to claim 6, characterized in that the direction of rotation of the needle rollers runs counter to the direction of rotation of the needle roller axes and the speed n of the needle rollers and the rotational speed N of the needle roller axes are selected so that the peripheral speed V _{needle of} the needles on at least one point in the material web in the area between the needle foot and the needle tip and at a location in the area between the needle entry and exit corresponds to the speed v _{mat of} the material web. Method for needling a material web according to claim 6, characterized in that the material web is guided in such a way that it can come into contact with the needle rollers along the circular movement circumscribed by about half the path of the needle rollers. Method for needling a material web according to claim 6, characterized in that a plurality of needle rollers of radius r rotating about their longitudinal axes are guided in a circle of radius R, the direction of rotation of the needle rollers running counter to the direction of rotation of the needle roller axes and the speed of the material _web v _mat , the speed n of the needle rollers and the rotational speed N of the needle roller axes are selected so that they correspond to the relationship (I) $${\text{v}}_{\text{mat}}\text{= 2 * π * r * n - 2 * π * (r + R) * N}$$

Method for needling a material web according to claim 6, characterized in that a plurality of back-up rolls rotating about their longitudinal axes are additionally provided and are guided in a circle, needle rolls and back-up rolls alternately following one another. Method for needling a material web according to claim 6, characterized in that a non-pre-consolidated nonwoven is treated in a pre-consolidation device and then subjected to needling according to claim 6. Method for needling a material web according to claim 11, characterized in that the pre-consolidation is carried out by means of water jets. Device for needling a material web (9) comprising a plurality of needle rollers (1) which can be rotated about their longitudinal axis (3) and whose respective longitudinal axes (3) can in turn be moved on a circular path. Apparatus according to claim 13, characterized in that it additionally comprises a plurality of support rollers (2) rotatable about their longitudinal axes (4), the respective longitudinal axes (4) can in turn be moved on a circular path and the needle rollers (1) and back-up rollers (2) alternately follow one another. Device according to claim 13, characterized in that the support rollers (2) can be moved in the radial direction. Use of the device according to claim 13 for needling material webs, in particular nonwovens or laminates.

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