APPARATUS AND METHOD FOR SUPPLYING A CONTINUOUS WEB OF CRIMPED SHEET MATERIAL

Abstract

An apparatus for supplying a continuous web of crimped sheet material (2) to a rod forming device comprises:—a winding unit (3) for unwinding the sheet material from a bobbin (21) on which the sheet material is provided;—a crimping unit (7) for crimping the sheet material,—a cutting unit (5) for cutting the continuous web of sheet material (2) to a predetermined width, the cutting unit (5) being arranged upstream of the crimping unit (7) when viewed in the direction of transport of the sheet material (2); and—a control unit (9) for controlling the various units of the apparatus in response to sensor signals received from the respective units.

Description

The present invention relates to an apparatus and method for supplying a continuous web of crimped sheet material.

An apparatus of this type is known, for example, in the field of production of filters for smoking articles such as cigarettes. These filters are typically made either from cellulose acetate tow or from a crimped sheet material, for example from paper. The crimped paper is supplied to a filter making device in form of a continuous web. The filter making device forms a filter rod from the continuous web of crimped paper supplied to the filter making device, and subsequently cuts the filter rod into discrete filters of a predetermined length.

An apparatus for supplying a continuous web of crimped paper to a filter making device is known. In the prior art apparatus, the outlet of the crimping unit is arranged so as to directly feed the crimped paper to the filter making device. A control unit controls the various units of the apparatus and its operation, allowing little flexibility for variation, e.g. with respect to manufacture of different types of filters.

It would be desirable to provide an apparatus which provides for enhanced flexibility with respect to various types and properties of filters that can be made using the crimped sheet material supplied by the apparatus. This would provide enhanced productivity and cost efficiency for meeting a variety of consumer needs.

In one aspect, the present invention provides an apparatus for supplying a continuous web of crimped sheet material to a rod forming device. The apparatus comprises a winding unit for unwinding the sheet material from a support on which the sheet material is provided, such as a bobbin, and a crimping unit for crimping the sheet material. The apparatus further comprises a cutting unit for cutting the continuous web of sheet material to a predetermined width, and a control unit for controlling the various units of the apparatus in response to sensor signals received from the respective units.

The cutting unit is arranged upstream of the crimping unit when viewed in the direction of transport of the sheet material. This aspect is advantageous since it allows cutting of the sheet material to different widths, which may for example allow to control the density of a filter rod. For this purpose, the cutting elements are displaceable in a direction perpendicular to the direction of transport of the sheet material. Preferably, the cutting elements are symmetrically displaceable relative to the center line of the path along which the sheet material is transported through the apparatus. This allows cutting the sheet material of the web to a desired width and offers many advantages.

For example, the filters of regular filter cigarettes have a diameter of about 7.6 millimeters (mm), while the filters of so-called “slim cigarettes” have a diameter of about 7.1 millimeters (mm). Accordingly, when a web of sheet material has been processed for the production of filters for regular filter cigarettes and it is now desired to switch to the production of filters for slim cigarettes, up to now the bobbin carrying the web for the filters of regular filter cigarettes is replaced with a bobbin carrying a web having the width required for the filters of slim filter cigarettes. This replacement of the bobbin is a comparatively laborious and time consuming process. One advantage of the embodiment of the apparatus comprising the afore-described cutting unit is that such replacement of the bobbin is no longer required. Instead, the cutting unit can be adjusted to cut the sheet material for the production of filters for regular filter cigarettes to the width required for the filters of slim filter cigarettes as the web of sheet material passes the cutting unit.

A further advantage of the cutting unit is that it allows for an easy variation of the resistance to draw. By cutting the sheet material to a smaller width, the amount of crimped sheet material contained in the filter is reduced whereby the resistance to draw is lowered given that the other parameters, for example an amount of add-on material dispensed as described further below, remain unchanged. Also, if a particular resistance to draw is desired and a specific sheet material is to be processed the sheet material can be cut to a width which is such that after the crimping and rod formation results in the desired resistance to draw. Accordingly, this allows the processing of different types of sheet materials, for example paper or plastic film, as well as of different widths of sheet materials.

In accordance with another aspect of the invention, the apparatus further comprises a dispensing unit for adding add-on material to the sheet material. The dispensing unit is arranged downstream of the crimping unit when viewed in the direction of transport of the sheet material, and upstream of a rod forming device to which the crimped sheet material is supplied. Thus, add-on material can be added to the crimped sheet material before the crimped sheet material is supplied to a rod forming device, for example to a filter making device. Alternatively, the rod forming device may be comprised in the apparatus according to the invention.

Adding the add-on material after crimping is advantageous. For example, because the add-on material is added to the already crimped sheet material, the add-on material or at least a substantial amount thereof is retained in or on the crimped structures of the sheet material. The crimped sheet material with the add-on material is subsequently supplied to the rod forming device where a rod of filter material is formed which is then cut to size to form the individual filters having a predetermined length.

The term “sheet material” in this respect is meant to comprise any flat web of a material suitable for the production of filters for smoking articles, such as for example paper or plastic films. The sheet material can be either a single-layer sheet material or can be a multi-layer sheet material.

The term “add-on material” includes, for example, liquid, gel-like or pasty materials, as well as particulate materials comprising, for example, discrete particles, such as bulk material, powder, granules or the like, and objects suitable for inclusion into a cigarette filter, such as capsules or beads and elongate material, as for example, thread. Preferably, the add-on material is a particulate material.

The addition of add-on material to the crimped sheet material may generally serve various purposes. For example, it may serve the purpose of adding to the smoke drawn in by a consumer through the filter. For example, the add-on material may comprise menthol, tobacco or other desired flavors. Alternatively or in addition, the add-on material may serve to remove or alter at least part of the gaseous or solid constituents of the smoke. For example, the added particulate material may comprise activated carbon granules.

Also, the resistance to draw of the final filter can be varied by adding the add-on material. For example, by variation of the amount of add-on material, for example particulate material, added to the sheet material per unit of sheet material the resistance to draw can be lowered or raised.

The resistance to draw can also be varied by other capabilities of the apparatus, thus increasing flexibility of the apparatus according to the invention. Due to the apparatus being capable of processing different types of sheet material the resistance to draw can be varied through selection of the type of sheet material processed. As an example, it is possible to select paper or plastic film. Also, single layer sheet materials or multi-layer sheet materials can be selected. Still further, due to the apparatus being capable of processing sheet materials having different thicknesses the resistance to draw can be varied through selection of the thickness of the sheet material processed by the apparatus. Yet further, due to the apparatus being capable of processing sheet materials having different widths the resistance to draw can be varied through selection of the width of the sheet material processed by the apparatus. The width of the sheet material is related to the density of the crimped sheet material in the filter after rod formation. Therefore, the apparatus according to the invention is very flexible and allows the supply of crimped sheet material which allows the production of filters of a large variety of types and properties. In addition, an apparatus according to the invention is particularly advantageous as the cost for manufacture filters comprising crimped sheet material is typically lower than the cost for manufacture of filters comprising cellulose acetate tow.

According to an aspect of the invention, changing the resistance to draw of a filter is done by adapting the cut width of the sheet material. Changing the resistance to draw of a filter may comprise the step of measuring a filter parameter and generating a signal indicative of the measured filter parameter. The cut width of the sheet material may then be adapted in response to the signal.

Preferably, a filter parameter to be measured for the adaption of the cut width of the sheet material comprises at least one of, but is not limited to: resistance to draw, rod firmness, weight, transparency, density and moisture content.

According to another aspect of the apparatus according to the invention, the crimping unit comprises a first pair of crimping rollers for engaging and crimping the continuous web of sheet material being transported between them. The crimping rollers have a surface which is provided with means adapted to crimp the sheet material in the direction of transport of the sheet material. Preferably, the crimping rollers have a surface which is provided with means adapted to crimp the sheet material in the longitudinal direction of the sheet material. By way of example, the means adapted to crimp the sheet material in the direction of transport of the sheet material may comprise a structure on the surface of the rollers. In particular such a structure may comprise for example crests and troughs running circumferentially about the axis of rotation of the rollers. The sheet material is crimped by transferring the structure to the sheet material as it passes between the rollers. The grooved structure transferred to the sheet material is particularly suitable to receive the add-on material, in particular in case the add-on material is a particulate material, or comprises capsules or beads. Crimping the sheet material in the longitudinal direction also reduces the stability of the sheet material in a transverse direction. Thus, the subsequent formation of the rod (compression of the sheet material into a cylindrical form) which is then cut to form the individual filters is facilitated.

In accordance with another aspect of the invention, the crimping unit comprises a second pair of crimping rollers for engaging and crimping the continuous web of sheet material being transported between them. The crimping rollers of the second pair of crimping rollers have a surface which is provided with means adapted to crimp the sheet material in a direction transverse to the direction of transport of the sheet material. The term “transverse to the direction of transport of the sheet material” is to be understood to include directions other than perpendicular to the direction of transport of the sheet material. Preferably, the crimping rollers have a surface which is provided with means adapted to crimp the sheet material in a direction perpendicular to the direction of transport. By way of example, the means adapted to crimp the sheet material in the direction transverse to the direction of transport of the sheet material may comprise a structure on the surface of the rollers. This structure may comprise crests and troughs running in a direction parallel to the axis of rotation of the rollers. This structure is preferably provided on the entire surface of the rollers, so that the sheet material is crimped by transferring the structure of the rollers to the sheet material as it passes between the rollers. Alternatively, in some applications, it may be sufficient to crimp the sheet material only in sections in a transverse direction, such that some sections are crimped and others remain uncrimped in a transverse direction.

According to yet a further aspect of the invention, the crimping unit comprises both a first pair of crimping rollers having a surface being provided with means adapted to crimp the sheet material in a longitudinal direction relative to the direction of transport of the sheet material, and a second pair of crimping rollers having a surface being provided with means adapted to crimp the sheet material in a direction transverse to the direction of transport of the sheet material. This embodiment allows both the crimping of the sheet material in the longitudinal direction as well as in the transverse direction, resulting in a specific pattern being transferred to the sheet material as the sheet material passes between the first and second pairs of rollers. The structure on the surface of the respective pair of rollers can be embodied as described above.

For any of the afore-described embodiments the add-on material added to the crimped sheet material by the dispensing unit is preferably dispensed into the structure created in the crimped sheet material, for example into the longitudinally running troughs, into the transversely running troughs, or into the depressions of the pattern generated by the first and second pairs of rollers. This is particularly advantageous in case the add-on material is a particulate material. The particulate material dispensed into these troughs or depressions is retained therein as the crimped sheet material is subsequently fed into the rod forming device where the crimped sheet material is then compressed to form a rod.

According to yet another aspect of the invention, the winding unit may comprise a motor for driving the bobbin on which the sheet material is provided, and a brake. The control unit controls the motor and the brake in a manner such as to prevent the continuous web of sheet material from rupturing. In the state of the art, so far, the sheet material is pulled through the apparatus by the crimping rollers or by additional drive rollers of the crimping unit. According to the present invention, the motor of the winding unit assists in the unwinding of the sheet material from the bobbin which is particularly advantageous in case the sheet material is fragile. A fragile sheet material is prone to rupturing upon application of too high a pulling force by the rollers pulling the sheet material through the apparatus. The occurrence of an excessively high pulling force can thus be avoided. Preferably, the control unit receives a signal indicative of the actual tension of the sheet material. This signal can be processed and the motor of the winding unit can be controlled in response. Also, the brake of the winding unit can be controlled by the control unit. As the bobbin is close to getting empty, that is, at the time there is only little sheet material left on the bobbin, rotation of the bobbin must be stopped. The brake serves to achieve a smooth braking profile in order to avoid rupturing of the sheet material during this phase.

In accordance with a still further aspect of the invention, the apparatus further comprises a tensioning unit comprising a controlled actuator for applying and maintaining a predetermined tension to the sheet material during the transport of the sheet material through the apparatus. While passive tensioning units are known in the art, a tensioning unit comprising a controlled actuator is advantageous in that it allows active control of the tension applied to the sheet material. For example, known prior art tensioning units comprise a passive tensioning element having a fixed mass or weight through which tension is applied to the sheet material, however, this tension cannot be actively controlled. By way of example, the controlled actuator in accordance with this aspect of the invention may be a controlled pneumatic actuator, a controlled hydraulic actuator, a controlled electric actuator or may be any suitable other type of controlled actuator, in order to actively control the tension applied to the sheet material.

In accordance with yet a further aspect of the invention, the apparatus further comprises a softening unit which is arranged upstream of the crimping unit. The softening unit serves to facilitate the crimping operation by softening the sheet material to be crimped. By way of example, the softening unit may comprise a heat source for raising the temperature of the sheet material to be crimped. Such a softening unit comprising a heat source is particularly advantageous for plastic sheet material. An increase in temperature of the plastic sheet material softens the sheet material and may thus facilitate crimping of the sheet material. Any conventional heat source can be used for that purpose, such as for example an infrared radiator. Alternatively or in combination, the softening unit may comprise a moisture control means which is capable of raising or lowering the moisture content of the sheet material. For example, for raising the moisture content of paper sheet material, the moisture control means may comprise a nozzle arrangement for moisturizing the paper sheet material to be crimped. Should the moisture content be too high, the heat source may be activated to lower the moisture content of the paper sheet material.

Further advantageous aspects of the invention will become apparent from the following description of an embodiment of the apparatus according to the invention with the aid of the drawings in which:

FIG. 1 shows a schematic representation of an embodiment of the apparatus according to the invention;

FIG. 2 shows a schematic representation of a first embodiment of two crimping rollers of the apparatus according to the invention; and

FIG. 3 shows a schematic representation of a second embodiment of two crimping rollers (upper right) of the apparatus according to the invention, as well as of two schematic (upper and lower left) arrangements of crests and troughs provided on the surface of the crimping rollers.

In FIG. 1 an embodiment of the apparatus according to the invention is shown in a schematic representation. The apparatus comprises a driving unit 1 comprising driving rollers 10 for drivingly engaging and transporting a sheet material 2 through the apparatus. For example, the sheet material 2 may be paper or a suitable plastics film. The sheet material 2 is stored as a reel 20 on a bobbin 21 from which the sheet material 2 can be unwound with the aid of a winding unit 3.

Winding unit 3 comprises a motor 30 and a brake 31 capable of acting on the bobbin 21 so as to apply an additional driving or braking force to the bobbin 21. This is described in more detail below. A sensor 32 is provided in order to detect the distance between the sensor 32 and the outermost layer of the reel 20 so as to determine whether there is sufficient sheet material left on the bobbin 21 to continue operation.

The sheet material 2 is transported through the apparatus in the form of a web. A number of transport rollers 11 are provided along the path of the web of sheet material 2 through the apparatus. These transport rollers 11 serve to clamp or guide the web of sheet material 2 on its path through the apparatus.

The apparatus further comprises a tensioning unit 4 for applying and maintaining a predetermined tension to the web of sheet material 2 as it is transported through the apparatus. For this purpose, tensioning unit 4 comprises a controlled actuator 40 which can be actively controlled in order to always maintain the desired predetermined tension to the web of sheet material 2 even if the conditions during operation change.

The apparatus further comprises a cutting unit 5 for on-line cutting the sheet material 2 to the desired width. As has been explained above, if the width of the sheet material 2 to be supplied by the apparatus is to be changed (for example, due to a switching from the production of filters for regular filter cigarettes to the production of filters for slim cigarettes, or for any other reason, see above) it is no longer necessary to interrupt production and to change the bobbin 21 carrying the reel 20, but rather the cutting unit 5 allows to cut the sheet material 2 on-line to the desired width. The cutting unit 5 will be described in more detail below.

The apparatus further comprises a softening unit 6 for raising the temperature of the sheet material 2. The softening unit is arranged upstream of a crimping unit 7 for crimping the sheet material 2. The softening unit 6 assists in softening the sheet material 2 to facilitate crimping of the sheet material 2. As has already been explained above, softening unit 6 may comprise a heat source such as an infrared radiator, however, it may also comprise any other type of radiator suitable for this purpose. Such heat source is particularly advantageous in case the sheet material 2 is a plastic sheet material. Alternatively or in combination, softening unit 6 may comprise a moisture control means which is capable of raising or lowering the moisture content of the sheet material 2. This is particularly advantageous in case the sheet material 2 is a paper sheet material. For example, for raising the moisture content of the paper sheet material, the moisture control means may comprise a nozzle arrangement for moisturizing the paper sheet material to be crimped. Should the moisture content be too high, the heat source may be activated to lower the moisture content of the paper sheet material.

As already mentioned, the apparatus further comprises crimping unit 7 for crimping the sheet material 2. Crimping unit 7 may comprise a longitudinal crimping unit 70, or a lateral crimping unit 71, or both a longitudinal crimping unit 70 and a lateral crimping unit 71. The longitudinal crimping unit 70 as well as the lateral crimping unit 71 may comprise one or more pairs of rollers, as will be described in more detail below with the aid of FIG. 2 and FIG. 3.

The apparatus further comprises a dispensing unit 8 for adding add-on material to the sheet material 2. As already mentioned, preferably the add-on material is a particulate material. Dispensing unit 8 is arranged downstream of crimping unit 7 when viewed in the direction of transport of the sheet material 2, and upstream of a rod forming device to which the sheet material is supplied by the apparatus. Suitable rod forming devices are well-known in the art and, therefore, they are not described in detail.

Finally, the apparatus comprises a control unit 9 for controlling the various units, as this is indicated by the various dashed lines and arrows in FIG. 1.

In operation, the sheet material 2 stored as a reel 20 is unwound from the bobbin 21. Driving rollers 10 of driving unit 1 apply traction forces to the web of sheet material 2 causing the sheet material 2 to be unwound from reel 20 stored on bobbin 21. However, these forces may vary to some extent. Since rupturing of the sheet material 2 must be avoided, as control unit 9 receives a signal from driving unit 1 representative of high traction forces, control unit 9 may cause motor 30 to apply additional torque to bobbin 21 in order to prevent the sheet material 2 from rupturing. In a similar manner, control unit 9 may cause brake 31 to slow down the rotational speed of bobbin 21 so as to increase tension of the sheet material 2 should the tension have become too low. Also, at the time there is only a little amount of sheet material 2 left on reel 20—this being detected by sensor 32—brake 31 assists in controlling the rotational speed of bobbin 21 to avoid rupturing of the sheet material 2 during the stopping phase.

As already mentioned above, tensioning unit 4 comprising controlled actuator 40 assists in applying and maintaining a predetermined tension of the sheet material 2. This enables a reliable transport of the sheet material 2 through the apparatus and on the other hand prevents the sheet material 2 from rupturing by actively controlling the tension of the sheet material 2.

In the further path of the sheet material 2 through the apparatus cutting unit 5 may cut the sheet material 2 to the desired width in case the sheet material 2 unwound from reel 20 does not already have the required width. For that purpose, cutting unit 5 may comprise two laterally adjustable cutting wheels 50 (only one of them being shown in FIG. 1) which may be adjusted in a direction perpendicular to the direction of transport of the sheet material 2. Preferably, the cutting wheels 50 are symmetrically displaceable relative to a center line of the path of the sheet material 2.

Turning back to FIG. 1, with the aid of softening unit 6 the sheet material may be heated or moisturized prior to getting crimped in order to soften the sheet material 2 to facilitate crimping.

The sheet material 2 then enters crimping unit 7 which may comprise either a longitudinal crimping unit 70, or a lateral crimping unit 71, or both a longitudinal crimping unit 70 and a lateral crimping unit 71. For example, lateral crimping unit 71 comprises a pair of crimping rollers 710 as shown in FIG. 2. As the sheet material 2 passes through crimping rollers 710 it is crimped in a direction transverse to the direction of transport of the sheet material 2. In the embodiment shown in FIG. 2, the sheet material 2 is crimped in a direction perpendicular to the direction of transport, as this can be seen from the arrangement of the crests 711 and troughs 712 on the surface of crimping rollers 710. The dashed lines 713 on sheet material 2 shown in FIG. 2 are intended to indicate the grooves that have been crimped into the sheet material 2 in the direction of dashed lines 713.

Longitudinal crimping unit 70 may also comprise a pair of rollers 700, as this is shown in FIG. 3 (upper right). However, in contrast to lateral crimping unit 71 the rollers 700 of longitudinal crimping unit 70 may comprise crests 701 and troughs 702 on the surface of crimping rollers which are arranged as this is shown schematically in the upper left representation of FIG. 3. The lower left representation shows an alternative arrangement of crests 701 and troughs 702, however, although the peaks are shown to have a sharp contour they may be rounded. As the sheet material 2 passes through the pair of rollers 700 it is crimped in the longitudinal direction, that is, in the direction of transport of the sheet material 2. In the left hand representations of FIG. 3, the sheet material 2 passes out of the plane of the drawings towards the observer.

Of course, the apparatus may also comprise both a longitudinal crimping unit 70 and a lateral crimping unit 71. This results in a pattern of longitudinally and transversely arranged recesses in the sheet material.

Subsequently, the sheet material passes through the dispensing unit 8 where the add-on material, preferably particulate matter, is added to the crimped sheet material 2. The particulate matter may be dispensed into the grooves crimped into the sheet material 2 by the crests 711 or 701 of the rollers 71 or 70, or into the recesses, respectively.

The sheet material to which the particulate material has been added may then be drawn through a converging funnel to form a rod of compressed sheet material containing the particulate matter. This rod of compressed sheet material can then be processed by a filter making apparatus in the conventional manner.

Claims

1. Apparatus for supplying a continuous web of crimped sheet material to a rod forming device, the apparatus comprising

winding unit or unwinding the sheet material from a bobbin on which the sheet material is provided;

a crimping unit for crimping the sheet material,

a cutting unit for cutting the continuous web of sheet material to a predetermined width, the cutting unit being arranged upstream of the crimping unit when viewed in the direction of transport of the sheet material; and a control unit for controlling the various units of the apparatus in response to sensor signals received from the respective units, wherein

the cutting unit comprises cutting elements displaceable in a direction perpendicular to a direction of transport of the sheet material for adjusting the width of the sheet material.

2. Apparatus according to claim 1, further comprising a dispensing unit for adding an add-on material to the sheet material, wherein the dispensing unit is arranged downstream of the crimping unit when viewed in the direction of transport of the sheet material, and upstream of the rod forming device to which the crimped sheet material is supplied.

3. Apparatus according to claim 1, wherein the crimping unit comprises a first pair of crimping rollers for engaging and crimping the continuous web of sheet material being transported between them, the crimping rollers having a surface adapted to crimp the sheet material in the direction of transport of the sheet material.

4. Apparatus according to claim 1, wherein the crimping unit comprises a second pair of crimping rollers for engaging and crimping the continuous web of sheet material being transported between them, the crimping rollers having a surface adapted to crimp the sheet material in a direction transverse to the direction of transport of the sheet material.

5. Apparatus according to claim 3, wherein the crimping unit comprises both the first pair of crimping rollers having a surface adapted to crimp the sheet material in a longitudinal direction relative to the direction of transport of the sheet material, and a second pair of crimping rollers having a surface adapted to crimp the sheet material in a direction transverse to the direction of transport of the sheet material.

6. Apparatus according to claim 1, wherein the winding unit comprises a motor for driving the bobbin on which the sheet material is provided and a brake, the control unit controlling the motor and the brake in a manner such as to prevent the continuous web of sheet material from rupturing.

7. Apparatus according to claim 1, further comprising a tensioning unit comprising a controlled actuator for applying and maintaining a predetermined tension to the sheet material during the transport of the sheet material through the apparatus.

8. Apparatus according to claim 1, further comprising a softening unit for softening the sheet material to be crimped, the softening unit being arranged upstream of the crimping unit when viewed in the direction of transport of the sheet material.

9. Apparatus according to claim 1, wherein the sheet material is one of paper, plastic, metal or is a laminate of at least two of paper, plastic and metal.

10. Method for supplying a continuous web of crimped sheet material to a rod forming device, the method comprising the steps of

unwinding the sheet material from a bobbin on which the sheet material is stored;

transporting the sheet material to a crimping unit;

cutting the sheet material to a predetermined width;

crimping the sheet material;

supplying the crimped sheet material to the rod forming device, wherein cutting the sheet material to a predetermined width is performed prior to crimping the sheet material; and

varying the width of the sheet material by displacing cutting elements in a direction perpendicular to a direction of transport of the sheet material.

11. Method according to claim 10, further comprising the step of adding an add-on material to the sheet material, wherein adding the add-on material to the sheet material is performed after crimping of the sheet material and prior to supplying the crimped sheet material to the rod forming device.

12. Method according to claim 10, wherein the step of varying the width of the sheet material comprises changing the resistance to draw of a filter.

13. Method according to claim 12, wherein the step of changing the resistance to draw of a filter comprises the step of measuring a filter parameter, generating a signal indicative of the measured filter parameter and adapting the cut width of the sheet material in response to the signal.

14. Method according to claim 13, wherein the filter parameter comprises at least one of: resistance to draw, rod firmness, weight, transparency, density and moisture content.

15. (canceled)

16. Apparatus according to claim 2, wherein the crimping unit comprises a first pair of crimping rollers for engaging and crimping the continuous web of sheet material being transported between them, the crimping rollers having a surface adapted to crimp the sheet material in the direction of transport of the sheet material.

17. Method according to claim 11, wherein the step of varying the width of the sheet material comprises changing the resistance to draw of a filter.

18. Method according to claim 12, further comprising the step of incorporating the filter into a smoking article.