HK1021118A - Method and apparatus for treatment of filter tow sliver - Google Patents

Description

Method and device for treating short filtered flax strips

The invention relates to a method for processing short filter flax strips, in which method the short filter flax strips are formed into bundles of a continuously reduced cross section in guide grooves, which are then wrapped with a wrapping strip to form filter ropes, which are cut into filter rods, wherein during bundling, compressed gas is blown into the short filter flax strips, which is discharged downstream from the bundle region through the grooves in the region of gas discharge openings.

The invention further relates to a device for treating filter tow flax strips, comprising a guide channel with a reduced channel cross-section in the form of a strip bundle, an inlet for the supply of gas under pressure and a downstream discharge area for the discharge of air blown into the filter tow flax.

The term "gas" as used herein refers in particular to air, other gases such as CO may also be used₂Or steam.

The term "filter tow" as used herein refers to wool (Vlies) made from a plurality of crimped synthetic staple fibers and/or filaments, such as cellulose acetate, staple fibers and/or filaments.

The term "guide groove" as used herein refers to a groove which is used as a "guide pin" in the filter preparation technique by means of a rope making machine, and the cross section of the groove of the filtered tow fed into the groove is reduced to a bunch shape in the feeding direction, and the cross section is reduced to approximate the cross section of the rope.

The terms "upstream" and "downstream" as used herein refer to the direction of conveyance of the filtered flax as "flow".

It is known from EP-B1-0269915 to blow compressed air into the filtered flax in the region of the positioning pins and then to discharge the air through the sieve-like openings in order to increase the uniformity of the filter rods.

The object of the invention is to further improve the uniformity of the filter rods produced.

The object of the invention is achieved in that downstream of the air outlet area, a further air flow is blown into the filtered short linen strip, and in that in a further downstream air outlet area air is discharged through the slot.

Other configurations and other embodiments of the invention are defined in the following method claims.

The device described at the outset is characterized in that downstream of the air outlet region there is provided an inlet for the introduction of air under pressure into the guide groove and a further air outlet region for the discharge of air blown into the filtered flax and discharged from the guide groove.

Other configurations and other embodiments of the device of the present invention are defined in the following claims.

A surprising advantage of the method and apparatus of the present invention is that the uniformity of the filter rods is significantly improved, as shown in the comparative photographs of fig. 5 and 6.

The present invention will be described in detail below with reference to embodiments. In the figure:

fig. 1 shows a side view of a processing machine for filtering short flax consisting of cellulose acetate.

Fig. 2 shows the guide groove (guide pin) of the filter tow with the format band (format band) in an enlarged side view.

Fig. 2a shows an enlarged view of the vent slot corresponding to fig. 2.

Fig. 3 shows a plan view of a guide groove (positioning pin) corresponding to fig. 2.

Fig. 4 shows a bottom view of the guide groove (positioning pin) corresponding to fig. 2 and 3.

Figure 5 shows a photographic view of a filter rod made according to the prior art.

Figure 6 shows a photographic view of a filter rod made in accordance with the present invention.

Figure 1 shows an arrangement of the present inventor for treating filter tow, preferably comprised of cellulose acetate, which is well known in the tobacco processing industry under the trade mark AF.

Starting from a ball 1 of piled, filtered, short, flax-overlapping strips of cellulose acetate, the strips 3 are drawn by a pair of drive rollers 2, for example consisting of a raceway and brake rubber rollers, loosened and spread by an air jet 4, conveyed by a roller 6 and further treated and loosened by another air jet 7. A pair of traction rollers 8, which are not driven, holds the web 9 formed by the spread threads of the filtered flax. The other pair of transmission rollers 11 (for example, also formed by a raceway and a brake rubber roller) has a faster transmission speed than the pair of rollers 2, so that the wires of the web 9 running between the pairs of rollers 2 and 11, which wires are conveyed in a plane and are substantially formed by a single closely arranged wire, can be stretched. A spray device 12 is arranged downstream of the roller pair 11, and drops of a softening agent 13, for example triazacyclobutene, are sprayed by means of rotating brushes 14 downward onto the threads of the web 9 consisting of short flax material, which is conveyed on a plane. After deflection by the further pair of driving rollers 16, the web 9, the width of which is narrowed, passes through the compressed air inlet nozzle 17 with the compressed air connection line 17a to a not shown flared inlet 18, which is connected to a filter core machine KDF, for example of the type KDF2 or of the type KDF3 of the inventor known in the tobacco industry. The arrow 19 indicates the direction of movement of the web 9.

Connected to the bell mouth 18 is a so-called formatting device 20 with a guide groove (hereinafter also referred to as "guide pin") for the cut flax shreds which are reduced in cross section, so that, during the transport of the cut flax shreds, they form a continuous strand due to the reduction in cross section until they reach the cross section of the filter rod required in the tobacco processing industry for the preparation of filter cigarettes. The filtered flax is drawn by the formatting device 20 by a so-called formatting belt 22 which is transported together with a wrapping strip 24, for example a paper strip, by a wrapping roller 23. In the formatting device, a strip of paper 24 coated with glue on one side wraps the short filter strings, which are then formed in a known manner, not shown, and cut into filter rods. The entire formatter is shown with only the activation part with the positioning pin 21. Other parts of the formatting device, such as the glue booth, etc., are not shown as they are not the subject of the present invention.

Fig. 2 to 4 show guide grooves 21, in practice also referred to as "guide pins", which narrow in the direction indicated by arrow 19, i.e. whose cross section decreases continuously. The cross section of the filter tow strips is therefore likewise narrowed until a diameter close to the filter string is reached. Fig. 2 shows only the formatting strip 22 as a backing strip, although in practice it is highly arcuate on both sides of the locating pin 21, thereby covering a portion of the locating pin. Thus eliminating this portion of the formatting strip.

At the first air inlet 26, compressed air is fed at 3 bar, for example, which flows inside the positioning pin 21 and the fully rotating filtered flax through the slit grooves 28 that are cut into three rows in the wall 27. Thereby entangling the fibers to increase the tensile strength of the filter rod produced therefrom in a desired manner. The angle of the air flow out of the wall 27 is 10 to 30 °, preferably 20 °, with the positioning pins as longitudinal axes, so that the filter material receives the transported components by the air. The blown air can be discharged from the positioning pin 21 through the sieve-like configuration of the outlet region 29. The vent slots 31 of the vent area are the same size, and in an embodiment, are circular with a diameter of about 0.5-1.5mm, e.g., about 1 mm. The vent slots may also have other configurations and sizes. A further air inlet 32 is located downstream of the air outlet region 29, from which compressed air at, for example, 2 bar is fed, which flows through the slit grooves 33, which are cut into three rows in the wall 27, inside the positioning pins 21 and in the filtered flax introduced therein. Re-entangling the fibers facilitates improved uniformity of the filter rods produced. The angle of the air flow out of the wall 27 is likewise about 10-30 deg., preferably about 20 deg., with the pin being the longitudinal axis. Additional air blown in can be discharged from the positioning pins 21 via further sieve-like outlet openings 34 arranged downstream. The exhaust grooves 36 are the same in shape and size as the exhaust grooves 31. A relatively small size of the vent slots is preferred because the fibers from the filtered fluff are not actually passed out. The pressure of the input air fluctuates up and down within a range of specified values.

Figure 5 shows the distribution of filtered flax in an open filter rod prepared according to the apparatus of EP-B10269915. One can see that the distribution is not uniform, having two thickening layers 41,42 of a central thickened shape, between which there is a thin material area 43.

Fig. 6 shows the distribution of the filtered flax material prepared according to the invention in an open filter rod. One can see that in practice the distribution of the filtered flax 44 is extremely uniform over the whole plane, which is why the quality of the filter rod is good.

Claims (14)

1. A method for processing short filter flax strips, in which method short filter flax strings are produced in a guide channel in the form of a continuous cross-sectionally reduced bundle, which are subsequently wrapped with a wrapping strip to form a filter string, which is cut into filter rods, wherein during bundling, compressed gas, preferably compressed air, is blown into the short filter flax strips, said compressed gas being discharged downstream from the bundle region through the channel in the region of a gas outlet, characterized in that: downstream of the air outlet zone, a further air stream, preferably air, is blown into the filter tow strip and the air is discharged through the slot in a further, downstream arranged air outlet zone.

2. A method according to claim 1, characterized in that: blowing in other air streams of reduced pressure as counter-current blowing-in air streams

3. Method according to claim 1 and/or 2, characterized in that: air is blown through the slots into the guide grooves, which, at least in part, extend with the majority of the components in the direction of movement of the filtered flax.

4. A method according to one or more of the preceding claims, characterized in that: air is discharged from the guide grooves in the region of the air outlet opening via a groove of constant cross section.

5. An apparatus for treating filter tow flax strips, comprising a guide channel with a reduced cross-section for the formation of a tow flax strip, an inlet for the supply of gas, preferably air, under pressure and a downstream discharge area for the air blown into the filter tow flax, characterized in that: downstream of the outlet opening region (29) there is a further inlet opening (32) for supplying gas, preferably air, under pressure into the guide channel (21) and a further outlet opening region (34) for discharging air blown from the guide channel (21) into the filtered flax.

6. The apparatus of claim 5, wherein: the pressure of the air blown into the other inlet and the filtered flax is lower than the pressure of the air blown into the filtered flax at the upstream located inlet.

7. The apparatus of claim 6, wherein: in the transport direction of the filtered flax, the pressure at the first air inlet is at least about 3 bar and the pressure at the other air inlets arranged downstream is at least about 2 bar.

8. Device according to one or more of claims 5-7, characterized in that: at least one of the discharge opening regions (29,34) of the guide groove (21) is formed in the shape of a screen.

9. The apparatus of claim 8, wherein: at least one of the vent regions has a vent groove (31,36) of constant cross-section.

10. Device according to claim 8 and/or 9, characterized in that: the exhaust port groove is made into a circular hole with a constant diameter.

11. Device according to one or more of claims 8-10, characterized in that: the diameter of the discharge grooves (31,36) is 0.8 to 1.2mm, preferably about 1.0 mm.

12. Device according to one or more of claims 5-11, characterized in that: at least one of the air inlets (26,32) in the guide groove (21) has a plurality of inlet grooves (28, 33).

13. The apparatus of claim 12, wherein: the angle between the air inlet slots (28,33) and the longitudinal axis of the guide slot (21) is < 90 deg..

14. A device according to claim 12 and or 13, characterized in that: at least one air inlet (26,32) in the guide groove (21) 5 has a slot (28,33) which extends at least partially together with the majority of the components in the direction of movement (19) of the filtered flax.