Method and apparatus for cutting filter materials

Abstract

A method of cutting filter materials in the tobacco industry wherein a filter material in the form of filter rods is fed to rotary knife unit, the filter rods are cut into segments by means of rotary knives pressing the filter rods against a guiding jacket characterised in that the rotary knives are cooled in the area behind the guiding jacket.

Description

The object of the invention is a method and an apparatus for cutting filter materials.

In the tobacco industry, particularly in the machines for manufacturing multi-segment filters used in cigarettes, there is a need of feeding multiple different filter segments from multiple feeding apparatuses. Among known segment feeding apparatuses are devices for feeding sets of filter segments, whereas one set of segments is formed by cutting one filter rod transported on a drum conveyor using a cutting head provided with rotary knives.

Systems for cutting filter materials into segments, in particular filter rods into segments used in multi-segment filters, where a number of individual segments with different physical properties is used, are known in the prior art. Rotary knife units, in particular made of steel, are utilised in the prior art.

In the Polish patent application P.394994, for example, the object of invention is a detachable cutting head for an apparatus for feeding filter segments provided with a drum conveyor having flutes for the transverse movement of filter rods, provided with rotary knives situated in knife units fastened in the housing of the head.

The object of invention in the Polish patent application P.395519 is a jacket for guiding filter segments to a filter segment feeding apparatus provided with a drum conveyor having flutes for the transverse movement of filter rods and a cutting head having multiple rotary knives fastened in the housing of the head, characterised by having a uniform, substantially cylindrical filter rod guiding surface. In addition, it has multiple slots for rotary knives of the cutting head.

From the GB 1043706 patent, a detachable cutting head provided with several rotary knives mounted on knife shafts is known.

In known filter rod cutting systems, no forced cooling systems are used because rotary knives made of steel easily give off heat to the air with ambient temperature. In the course of research on increasing the cutting speed, however, difficulties with the maintenance of the cutting surface quality occurred, whereas the quality of the cutting surface is mainly decreased by melting thereof. Such difficulties occurred in particular in case of the use of rotary knives made of tungsten carbide. Similar difficulties arose in case of the use of axially incompressible filter materials with a high hardness and of materials with the melting temperature in the range of 60° C. The purpose of the invention is to solve the problems which occur during filter material cutting with a high speed.

The gist of the invention is a method of cutting filter materials in the tobacco industry wherein by means of a drum conveyor provided on its circumference with flutes the filter material in the form of filter rods is fed to a rotary knife unit, the filter rods are cut into segments in the flutes of the drum conveyor in the area under a filter rod guiding jacket by means of rotary knives characterised in that the rotary knives are cooled in the area behind the guiding jacket.

Furthermore, a method of the invention is characterised in that the rotary knives are cooled to the temperature in the range between 5 and 25° C., preferably in the range between 15 and 25° C., and most preferably in the range between 20 and 25° C.

Furthermore, a method of the invention is characterised in that the rotary knives are cooled with compressed air, water, liquid nitrogen.

Furthermore, the rotary knives are cooled with a cooling medium in a closed cycle.

Furthermore, the rotary knives are cooled with a cooling medium in an open cycle.

Furthermore, the gist of the invention is an apparatus for cutting filter materials in the tobacco industry comprising a rotary knife unit provided with a filter rod guiding jacket for guiding filter rods conveyed in the flutes of the drum conveyor characterised in that in the area behind the guiding jacket a cooling unit reducing the temperature of the rotary knives is situated.

An apparatus of the invention is characterised in that the cooling unit comprises at least one cooling medium blowing nozzle for each knife.

An apparatus of the invention is characterised in that the cooling unit comprises two cooling medium blowing nozzles on two sides of a knife.

An apparatus of the invention is characterised in that the cooling medium nozzles are situated substantially perpendicular to the knife surface.

An apparatus of the invention is characterised in that the cooling medium nozzles are situated just at the cutting edges.

An apparatus of the invention is characterised in that the cooling unit operates in an open system. An apparatus of the invention is characterised in that the cooling unit operates in a closed system. An apparatus of the invention is characterised in that the rotary knife unit comprises rotary knives of tungsten carbide.

An apparatus of the invention is characterised in that the cooling unit is a unit for cooling with air, water or liquid nitrogen.

The substance of the invention is also an apparatus characterised in that a temperature sensor is assigned at least to one knife.

An advantage of the method and the apparatus according to the invention is the simplicity of design which allows performing filter material cutting at high speeds without worsening the physical characteristics of the filter material.

The object of the invention was shown in detail in a preferred embodiment in a drawing in which:

FIG. 1 diagrammatically shows an apparatus for cutting filter materials according to the invention.

FIG. 2 diagrammatically shows a view of a cooling head in an open configuration,

FIG. 3 diagrammatically shows a view of a cooling head in a closed configuration.

FIG. 1 diagrammatically shows an embodiment of the invention in a front, i.e. operator's, view. The drawing shows a drum conveyor 1 mounted on a plate 2 beneath a hopper 3. The drum conveyor 1 conveys filter rods 6 picked up from the hopper 3 in flutes 4 on the circumference 5 into the operating range of a rotary knife 8 unit 7. The filter rods 6 are placed into the space between the drum conveyor 1 and a guiding jacket 12 where they are cut by means of the rotary knives 8. The rotary knives 8 are situated with their axes of rotation 9 parallel to the axis of rotation 10 of the drum conveyor 1, whereas their cutting edges 11 go through the guiding jacket 12 in order to allow cutting of the rods 6 in the flutes 4. The rotary knives 8 are partly disposed in a cooling area 15 marked with a broken line and situated behind the guiding jacket 12. In the cooling area 15, cooling members 16 of a cooling head 17 preferably made of aluminium are situated, whereas to each knife at least one cooling member 16 is assigned. The cooling members 16 are members supplying a cooling medium to the cooling area 15. The cooling members 16 can be for example compressed air or gas nozzles; they can also supply a different cooling medium. The cooling of the cooling head 17 using ice-cold water, i.e. water with additives lowering its freezing point below 0° C., can also be designed. Also temperature sensors 18 are placed in the cooling head, whereas at least one temperature sensor 18 at one of the rotary knives 8 is designed in the cooling head. FIG. 2 shows a diagrammatic view of the rotary knives 8 and the cooling head 17 from the side of the drum conveyor 1.

During the operation of the apparatus, the rotary knives 8 cut the filter rods into segments, and their cutting edges and border heat up to a temperature depending on the kind of filter material being cut. For the purpose of stabilizing the temperature of rotary knives 8, cooling members 16 situated in fragments 19 of the cutting head 17 comprising or adjacent to a portion of the surface of rotary knives 8 have been designed in the cooling area 15. The cooling medium will flow to the cooled knives 8 in slots 13 between the fragments 19 of the cooling head 17 and the rotary knives 8. The function of the head 17 is to stabilize the temperature of the rotary knives during their operation. The cooling head 17 fulfils the function of a heat exchanger to which through feeders 21 the cooling medium from a cooling medium source 20 also used as a system for conditioning, i.e. cooling down and compressing, the cooling medium is supplied. An open cooling system shown in FIG. 2 is possible where the cooling medium, for example compressed air with a low temperature, is released to the environment. A cooling system in a closed configuration shown in FIG. 3 is also possible where the cooling medium is supplied through the feeders 21 to the nozzles 16. However, the heated cooling medium is carried from the slots 13 through drains 22 to the cooling medium source 20, whereas the medium is not released to the atmosphere.

In view of the costs, the preferred embodiment of the invention is a system with a closed cooling medium circulation.

In the preferred embodiments such cooling mediums as compressed air, water, liquid nitrogen are possible.

In the course of the research work, it was unexpectedly observed that cooling down of the rotary knives of tungsten carbide to the temperature of 25° C. brought favourable effects for the quality of the filter material cutting process.

During the conducted research it turned out that it was possible to stabilize the temperature of the knives in the range between 5° C. and 25° C. Preferably, the temperature was maintained in the range between 15° C. and 25° C., and most preferably in the range between 20° C. and 25° C.

Claims

1. A method of cutting filter materials in the tobacco industry wherein:

by means of a drum conveyor provided on its circumference with flutes the filter material in the form of filter rods is fed to a rotary knife unit;

the filter rods are cut into segments in the flutes of the drum conveyor in an area beneath a filter rod guiding jacket by means of rotary knives,

characterised in that

the rotary knives are cooled in the area behind the guiding jacket.

2. The method as in claim 1 characterised in that the rotary knives are cooled to a temperature in the range between 5 and 25° C.

3. The method as in claim 1 characterised in that the rotary knives are cooled with a cooling medium selected from a group consisting of: compressed air, water, and liquid nitrogen.

4. The method as in claim 1 characterised in that the rotary knives are cooled with a cooling medium in a closed cycle.

5. The method as in claim 1 characterised in that the rotary knives are cooled with a cooling medium in an open cycle.

6. An apparatus for cutting filter materials in the tobacco industry comprising:

a rotary knife unit provided with a filter rod guiding jacket for guiding filter rods conveyed in flutes of a drum conveyor,

characterised in that

the rotary knife unit comprises rotary knives, and

in a space behind the guiding jacket a cooling unit lowering the temperature of the rotary knives by means of a cooling medium is situated.

7. The apparatus as in claim 6 characterised in that the cooling unit comprises at least one cooling medium blowing nozzle for each knife.

8. The apparatus as in claim 6 characterised in that the cooling unit comprises two cooling medium blowing nozzles on two sides of a knife.

9. The apparatus as in claim 7 characterised in that the cooling medium nozzles are situated substantially perpendicular to the knife surface.

10. The apparatus as in claim 7 wherein the rotary knives have cutting edges, characterised in that the cooling medium nozzles are situated just at the cutting edges.

11. The apparatus as in claim 6 characterised in that the cooling unit operates in an open system.

12. The apparatus as in claim 6 characterised in that the cooling unit operates in a closed system.

13. The apparatus as in claim 6 characterised in that the cooling unit is a unit for cooling with air, water or liquid nitrogen.

14. The apparatus as in claim 6 characterised in that a temperature sensor is assigned at least to one knife.

15. The apparatus as in claim 6 characterised in that the rotary knife unit comprises rotary knives of tungsten carbide.

16. The method as in claim 2 characterised in that the rotary knives are cooled to a temperature in the range between 15 and 25° C.

17. The method as in claim 16 characterised in that the rotary knives are cooled to a temperature in the range between 20 and 25° C.