FILTER MANUFACTURING APPARATUS

Abstract

The invention relates to a filter manufacturing apparatus including a feed path adapted to continuously feed a filter material along a longitudinal transport direction, and a forming device connected to a terminating end of the feed path and adapted to form the filter material into a rod-shaped continuous filter body and deliver the formed continuous filter body. The forming device includes: a tubular element adapted to allow the filter material to pass therethrough to form the filter material into the continuous filter body; a heat source adapted to heat the filter material passing in the tubular element. A diameter measuring device is positioned at the outlet of the forming device and adapted to measure a diameter of the continuous filter body.

Claims

1. A filter manufacturing apparatus comprising: a feed path to continuously feed a filter material along a longitudinal transport direction: a forming device connected to a terminating end of the feed path to form the filter material into a rod-shaped continuous filter body and deliver the continuous filter body, the forming device including: a tubular element with through hole allowing the filter material to pass therethrough to form the filter material into the continuous filter body; a heat source to heat the filter material passing in the tubular element: a diameter measuring device positioned at an outlet of the forming device to measure a diameter of the continuous filter body; a pressurized fluid generator to blow pressurized fluid towards the filter material to transport the filter material into the tubular element; a control unit configured to receive signals from the diameter measuring device relative to the diameter of the continuous filter body and to send signals to the pressurized fluid generator to vary pressurized fluid production or to a display in order to visualize the measurement and configured to compare a signal relative of measured diameter to a reference diameter and to change a parameter in the pressurized fluid generator to increase fluid pressure in case the measured diameter is bigger than the reference diameter of more than a given amount.

2. The filter manufacturing apparatus according to claim 1, wherein the diameter measuring device comprises a tubular measuring element or a U-shaped measuring element, located downstream the tubular element, to allow the continuous filter body to pass therethrough to measure the diameter of the continuous filter body.

3. The filter manufacturing apparatus according to claim 2, wherein the diameter measuring device comprises one or more nozzles to blow a pressurized fluid to measure pressure fluid variations to determine the diameter of the continuous filter body.

4. The filter manufacturing apparatus according to claim 2, wherein the diameter measuring device comprises a laser source apt to measure the diameter of the continuous filter body.

5. The filter manufacturing apparatus according to claim 1, comprising a wrapping section located downstream the forming device to wrap the continuous filter body in a wrapping sheet.

6. The filter manufacturing apparatus according to claim 5, wherein the wrapping section includes a glue nozzle to distribute glue onto the wrapping sheet to close the wrapping sheet around the continuous filter body.

7. The filter manufacturing apparatus according to claim 6, comprising: a heating section located downstream the tubular element to heat up the wrapped continuous filter body.

8. The filter manufacturing apparatus according to claim 7, wherein the heating section is located downstream the diameter measuring device.

9. The filter manufacturing apparatus according to claim 1, comprising: a plasticizer addition unit arranged upstream an inlet of the tubular element to spout a plasticizer to the filter material.

10. The filter manufacturing apparatus according to claim 1, wherein the tubular element includes a tapered portion, so that its internal diameter decreases along the longitudinal transport direction.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The invention will be further described, by way of example only, with reference to the accompanying drawings in which:

[0043] FIG. 1 is a schematic view of an apparatus for forming a filter according to the invention;

[0044] FIG. 2 is a perspective view of a portion of the apparatus of FIG. 1;

[0045] FIG. 3 is a further perspective view of a portion of the apparatus of FIG. 1; and

[0046] FIG. 4 is a schematic lateral view in section of an element of the apparatus of FIG. 1.

[0047] Numeral 1 in FIG. 1 indicates an apparatus as a whole, for producing filter rods (not shown) or filters components, preferably for aerosol-generating articles.

[0048] Apparatus 1 comprises a transport device 3 to transport along a transport or feeding direction filter material, for example cellulose acetate or filter tow. Further, the apparatus 1 includes an inlet unit 2 adapted to form a continuous stream or strip of filter material, moistened with a hardening fluid or plasticizer, such as triacetin. The filter material is fed to the inlet unit 2 by the transport device 3. The moistening of the filter material with plasticizer takes place in a plasticizer unit, not shown in the drawings and known in the art. The plasticizer unit is located upstream the inlet unit 2. Downstream the inlet unit 2, the apparatus includes a rod forming unit 4, arranged in series to the inlet unit 2 and adapted to receive the flow or strip of filter material and to cause the hardening material to react to transform the filter material into a continuous axially rigid rod filter. Advantageously, the apparatus further comprises a wrapping unit 12 and a heating unit 6. Further, the apparatus may comprise a cutting unit 7, normally a rotating cutting head of known type, arranged downstream of the rod forming unit 4 and adapted to cut the continuous filter rod crosswise into filter segments (not shown).

[0049] Wrapping unit 12, transport device 3 and cutting unit 7 are known in the art and not further detailed below.

[0050] The rod forming unit 4 comprises a tubular element 8, shown in an enlarged view in FIG. 4, adapted to receive the filter material saturated with hardening material, for example along the arrow 30 depicted in FIG. 4 which is the transport direction of the transport device 3, and to shape the filter material crosswise so as to transform it into a moist, generally cylindrical filter body and to advance the tow body in the feed direction of the mentioned arrow to the further components of the apparatus 1.

[0051] Preferably the filter material is pushed inside the tubular element 8 along arrow 30 by means of a fluid jet, for example a pressurized air jet, formed by a pressurized fluid generator (not shown in the drawings).

[0052] Tubular element 8 defines a through hole 20 through which the filter material can pass. Preferably, the through hole 20 comprises an inner surface 21 which compresses the filter material to form a substantially cylindrical rod-like shape. Further, preferably the tubular element 8 includes a steam generator 9 comprising one or more nozzles 11 which can emit steam in the interior of the tubular element 8. The steam can harden the plasticizer present in the filter material and transform it into the substantially rigid filter rod or body.

[0053] The apparatus 1, downstream the outlet of the tubular element, comprises a cooling unit (not shown in the drawings) to cool down the continuous filter body by means of compressed air, preferably at room temperature.

[0054] Further, the apparatus 1 includes the wrapping unit 12 located downstream the rod forming unit 4 and the cooling unit, which wraps in a wrapping paper 13 (see FIG. 3) the filter rod exiting from the tubular element 8. The wrapping unit 12 includes nozzles (not visible in the drawings) to distribute cold glue onto the wrapping paper 13.

[0055] Further, the apparatus comprises a heating unit 6 located downstream the wrapping unit 12, in order to heat the cold glue and to obtain a proper closure of the wrapping paper 13 onto the hardened filter rod.

[0056] The apparatus 1 further comprises a diameter measuring device 10 located between the tubular element 8 and the wrapping unit 12. The diameter measuring device 10 is apt to measure the diameter of the filter body exiting the tubular element. The diameter measuring unit preferably includes a sleeve or U-shaped element (not shown) through which the continuous filter body can pass. The diameter measuring unit includes preferably a laser system and a display (both not visible) where the measurements of the diameter of the filter rod exiting the tubular element 8 are shown. Alternatively, the diameter measuring unit is preferably in communication with a central control unit 100 to which it sends signal relative to the diameter measurements of the filter body at the output of the tubular element 8.

[0057] Control unit 100 is adapted to receive the signals from measuring device 10 and to command the rod forming unit 4. Preferably, central control unit 100 commands the steam generator 9 and the pressurized fluid generator (not visible in the drawings). The central control unit 100 is adapted to change the pressure of the steam produced by the steam generator and, in alternative or in addition, the pressure of the fluid pushing the filter material into the tubular element 8 on the basis of the measurements from the diameter measuring unit 10. For example, as soon as the measuring unit 10 measures diameter variations above a given threshold, the pressure of the steam and/or the pressure of the fluid are changed so that the diameter of the continuous filter body at the exit of the tubular element 8 returns within the desired specifications. Alternatively or in addition, the cooling speed can be changed in the cooling unit, increasing or decreasing the flow rate of air flowing against the filter rod. In this way the effect of the plasticizer can be accelerated or decelerated.

[0058] Alternatively, an operator checking the display of the measuring device 10 adapts the settings or parameters of the apparatus as mentioned above with reference to the control unit 100 in case the diameter of the rod exiting the tubular element 8 is outside the required specifications.