GB2262429A

GB2262429A - Feed unit with a tobacco particle separator for cigarette manufacturing machines

Info

Publication number: GB2262429A
Application number: GB9226208A
Authority: GB
Inventors: Fiorenzo Draghetti; Roberto Polloni
Original assignee: GD SpA
Current assignee: GD SpA
Priority date: 1991-12-17
Filing date: 1992-12-16
Publication date: 1993-06-23
Anticipated expiration: 2012-12-16
Also published as: GB2262429B; ITBO910474A0; GB9226208D0; ITBO910474A1; DE4242325A1; IT1253915B

Description

2262429 FEED UNIT WITH A TOBACCO PARTICLE CIGARETTE MANUFACTURING MACHINES

SEPARATOR FOR The present invention relates to a feed unit with a tobacco particle separator for cigarette manufacturing machines.

On cigarette manufacturing machines, shredded tobacco is normally fed through an input feedbox into a bin housing a carding unit by which the tobacco is fed to a downward conduit defining a dropdown channel for the tobacco. The bottom end of the dropdown channel is normally connected to a basin from which extends upwards an upflow duct defining an upfeed channel for the tobacco, the top end of which is closed off by a permeable conveyor belt. Inside the upfeed channel, an upward air current, at least partially produced by suction through the conveyor belt, draws up the lighter part of the tobacco consisting of powder and relatively small shreds, while any lumps and/or woody parts drop by force of gravity into the basin.

As only a small portion of the material in the basin is actually waste quality, attempts have been made on known machines to separate the waste and reusable material inside the basin and feed the salvaged material into the upfeed channel. For this purpose, basins of extremely complex design have been devised, inside which variously oriented air jets of different pressure provide for breaking up any lumps and feeding the salvaged lighter material upwards.

The above solution, however,, presents several drawbacks. Firstly, the extremely complex design of the basin poses serious problems in terms of construction, as well as impairing the overall reliability of the feed unit on the machine. Secondly, the above solution fails to provide for consistently separating the lighter and heavier parts of the material in the basin, which process varies as a function of a relatively large number of parameters depending on the type and condition of the shredded tobacco. For example, the damper the tobacco is, the harder it is to separate the reusable particles, which tend to adhere more strongly and so form lumps that are more difficult to break up.

To overcome the aforementioned drawbacks,, USA Patent N.4,729,388 relates to a cigarette manufacturing machine with a tobacco particle separator,, whereby the heavier parts of the tobacco collected in the basin are fed to a separator defined by an upside down U-shaped conduit with an air current, in which the tobacco is transported in the air flow direction for separating the actual waste from the reusable material. Though a great 1 improvement as compared with known machines of the aforementioned type, the above solution is relatively cumbersome and does not always provide for effective separation.

It is an object of the present invention to provide a feed unit for cigarette manufacturing machine, designed to enable highly effective, straightforward, low-cost separation of the actual waste material in the tobacco, the rest of which is fed entirely to the production machine.

According to the present invention, there is provided a feed unit with a tobacco particle separator for cigarette manufacturing machines, said unit comprising a dropdown channel for shredded tobacco; an upfeed channel for said tobacco, the top end of which is closed off by a permeable conveyor belt by which the tobacco is retained by suction and fed to the machine; a basin communicating with the respective bottom ends of said dropdown channel and said upfeed channel; and separating means for separating from said shredded tobacco the heavier parts unsuitable for manufacture of the cigarettes; characterized by the fact that said separating means comprise a cyclone separating device; means for generating an upward air current inside the cyclone device; means for feeding into the cyclone device, and in the opposite direction to said upward air current, the heavier tobacco particles collected in said basin; and means for connecting said cyclone separating device to at least one of said dropdown and upfeed channels.

A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:

Fig.1 shows a schematic side section of a feed unit for a cigarette manufacturing machine in accordance with the present invention; Fig.2 shows a larger-scale section of a detail in Fig. 1.

Number 1 in Fig.1 indicates a feed unit forming part of a cigarette manufacturing machine 2, the other parts (all known) of which are not shown for the sake of simplicity. Unit I provides for feeding shredded tobacco 3 to a wrapping unit (not shown) on machine 2 by means of a permeable conveyor belt 4 (shown only schematically) forming part of a more complex conveyor system (not shown),, and which provides for retaining tobacco 3 by suction and feeding it to the wrapping unit on machine 2. for which purpose, it is connected in known manner (not shown) to known suction means (not shown).

Feed unit 1 comprises an input feedbox 5 through which shredded tobacco 3 is fed into a bin-6 and on to a conveyor belt 7 by which it is fed to a carding unit 8 housed inside bin 6. Carding unit 8 feeds tobacco 3 into a dropdown channel 9. the bottom end 10 of which is controlled by a distributor 11 for receiving the tobacco from channel 9 and distributing it evenly on to a conveyor 12 sloping slightly upwards towards the bottom end 13 of an upfeed channel 14. the top end of which is closed off by conveyor belt 4. Bottom end 13 of channel 14 communicates with a catch basin 15 underneath, and conveyor 12 connects bottom ends 10 and 13 of channels 9 and 14 to each other and to basin 15.

A further input for the tobacco removed by a shaving device (not shown) from the layer of tobacco fed by conveyor 4 to the wrapping unit is represented by conveyor 16. which unloads the shaved-off tobacco on to a vibratory tray 17 underneath carding unit 8, from where it is fed, together with the tobacco processed by carding unit 8, into channel 9, in the example shown# through the top end 18 of channel 9.

on reaching channel 14. the tobacco is fed upwards along channel 14 to conveyor 4 by an upward air current produced by a blower 19 underneath basin 15 and fed into channel 14 through a number of inlets 20 with known choking means for regulating air flow. In actual practice, however, not all the shredded tobacco at bottom end 13 is fed upwards along channel 14, any heavier particles of which,, consisting of waste material, such as ribs of various sizes, or lumps escaping carding unit 8, drop down into basin 15 through a rotary valve unit 21, and are removed by a suction conduit 22 (shown partially by the dotted line in Fig.1) connecting basin 15 to a cyclone separating device 23.

With reference also to Fig.2,, cyclone separating device 23 comprises a substantially cylindrical housing 24 in turn comprising a top portion 25. and a bottom portion 26 opposite portion 25 and mounted on a base 27. Conduit 22 terminates tangentially inside top portion 25 and connects it to the inside of basin 15. A nozzle 28 is provided inside housing 24, beneath top portion 25. and defines. with and inside housing 24j, a variable-section annular conduit 29 hydraulically connecting top portion 25 to bottom portion 26, which presents lateral openings 30. A conduit 31 with a flow regulating throttle valve 32 feeds pressurized air into nozzle 28, the outlet 33 of which is located at the inlet 34 of an output conduit 35 connected to the inside of housing 24 beneath top portion 25. More specifically. conduit 35 is positioned coaxial with nozzle 28, facing outlet 33. with a small amount of clearance between inlet 34 and nozzle 28.

In actual use, nozzle 28 emits a high-speed jet of pressurized air into conduit 35 at the top end portion of annular conduit 29. thus forming inside housing 24 a vacuum for drawing in outside air through openings 30. and so producing inside cyclone device 23 an upward air current along annular conduit 29. from bottom portion 26 to inlet 34 of conduit 35. A powered dispersing plate 36,, mounted for rotation inside housing 24 and coaxial with nozzle 28. is located beneath top portion 25. between this and nozzle 28, for shielding top portion 25 4 from nozzle 28 and the air jet emitted by the same. more specifically, plate 36 provides for shielding from nozzle 28 peripheral holes 37 connecting portion 25 and conduit 29 and formed through a partition wall 38 in housing 24, for separating portion 25 from the rest of housing 24.

Plate 36 comprises a tubular hub 39 coaxial with conduit 35. fitted in idle manner to housing 24 on bearings 40. and which is rotated by a motor 41 via a gear drive 42, and in turn rotates plate 36. Hub 39 is so located as to define a first portion 43 of conduit 35 having inlet 34, which is thus flush with plate 36. and extending in substantially fluidtight manner through top portion 25 of housing 24. In the example shown,, dispersing plate 36 is truncated-cone-shaped with the wider end facing downwards (towards bottom portion 26) and having a diameter extending close to the axes of holes 37 formed in a circle through partition 38 and concentric with portion 43 of conduit 35.

As shown in Fig.2, variable-section annular conduit 29 defined between housing 24 and nozzle 28 comprises a number of chambers 44 connected in series and defined between respective lateral segments 45a,, 45b. 45c of nozzle 28 of different external shape and size. and respective rings 46 projecting from the inner lateral wall 47 of housing 24. Annular conduit 29 terminates at plate 36 with said top end portion, which is defined by an upward-flaring chamber 44a.

At base 27, cyclone device 23 also comprises a vibratory sieve 48 located beneath bottom portion 26 and operated in known manner by an eccentric drive 49; and a second output conduit 50 having an inlet in the form of a feedbox 50a underneath sieve 48, which retains the heavier waste tobacco and unloads it off device 23 and on to a waste tobacco conveyor 51.

As shown in Fig.l. conduit 35 extends from the top of device 23 and terminates inside bin 6 at conveyor 7 and immediately upstream from carding unit 8, so that it communicates with the top end 18 of channel 9; and conduit 50 extends from device 23, beneath bottom portion 26, and upwards to terminate inside bin 6 at an inclined plate 52 located beneath carding unit 8 and to the side of channel 9. Plate 52 is supplied by conduit 50 with tobacco particles 53 from sieve 48, and connects conduit So to the bottom end 10 of channel 9. More specifically, plate 52 provides for unloading tobacco particles 53 on to the end of conveyor 12 located upstream from distributor 11 in relation to the tobacco feed direction shown by arrow 54, so that particles 53 are mixed with and fed to channel 14 together with the tobacco processed by carding unit 8.

In actual use, the heavier particles collected in basin 15 are sucked into conduit 22 by the air current produced by the vacuum in chamber 44a and/or by known blowing means (not shown), and are fed into device 23 in the opposite direction to the upward air current inside the same. Inside device 23, the heavier particles are separated into lighter particles for recycling and heavier waste particles by virtue of the combined action of: feeding the tobacco tangentially into device 23, so that it spirals down into conduit 29; the upward countercurrent, which provides for breaking up any lumps, partially drying any damp tobacco, and expelling the lighter tobacco particles into conduit 35; chambers 44, which provide for sharp variations in the cross section of conduit 29 (wider at chambers 44 and narrower between one chamber and another), thus resulting in sharp variations in the speed of the upward air current and the formation of stationary vortices in chambers 44; impact/friction on rings 46; and the presence of sieve 48. Most of the reusable tobacco particles are thus separated as they drop down into conduit 29, regardless of the nature of the tobacco, and are fed back along conduit 35 to carding unit 8 where they are mixed with tobacco 3. Additional lighter particles, mainly in the form of powder and even adhering firmly to the waste material, may be salvaged mechanically at the sieving stage, wherein they are sucked into conduit 50 beneath sieve 48 and fed back into bin 6, downstream from unit 8 and directly to the bottom to channel 9.

Claims

1) A feed unit (1) with a tobacco particle separator for cigarette manufacturing machines, said unit (1) comprising a dropdown channel (9) for shredded tobacco; an upfeed channel (14) for said tobacco. the top end of which is closed off by a permeable conveyor belt (4) by which the tobacco is retained by suction and fed to the machine (2); a basin (15) communicating with the respective bottom ends (10. 13) of said dropdown channel (9) and said upfeed channel (14); and separating means for separating from said shredded tobacco the heavier parts unsuitable for manufacture of the cigarettes; characterized by the fact that said separating means comprise a cyclone separating device (23); means (28. 31) for generating an upward air current inside the cyclone device (23); means (22) for feeding into the cyclone device (23), and in the opposite direction to said upward air current. the heavier tobacco particles collected in said basin (15); and means (35. 50) for connecting said cyclone separating device (23) to at least one of said dropdown and upfeed channels (!9,, 14).

2) A feed unit (1) as claimed in Claim -1, characterized by the fact that taid cyclone separating device (23) comprises a substantially cylindrical housing (24); a supply conduit (22) terminating tangentially inside a top portion (25) of said housing (24) and connecting said top portion (25) to the inside of said basin (15); a nozzle (28) housed inside said housing (24), beneath said top portion (25), and defining, with and inside said housing (24), a variable- section annular conduit (29); a first output conduit (35) connected to the inside of said housing (24), beneath said top portion (25), and coaxial with said nozzle (28), with its inlet (34) located substantially at the outlet (33) of said nozzle (28); means (31, 32) for supplying pressurized air to said nozzle (28); and means (30) for enabling air intake into said housing (24) and formed on the bottom portion (26) of the same; said variable-section annular conduit (29) defined between the housing (24) and nozzle (28) connecting said bottom portion (26) to said top portion (25) of the housing (24).

3) A feed unit (1) as claimed in Claim 2, characterized by the fact that said cyclone separating device (23) also comprises a powered dispersing plate (36) mounted for rotation inside the housing (24), coaxial with the nozzle (28), and located beneath said top portion (25) and between this and the nozzle (28), for shielding said top portion (25) of the housing (24) from the nozzle (28); said dispersing plate (36) comprising a tubular hub (39) coaxial with said first output conduit (35); and said hub (39) defining the inlet (34) of said first output conduit (35)r and a first portion (43) of said conduit (35) extending in substantially fluidtight manner through the top portion (25) of the housing (24).

4) A feed unit (1) as claimed in Claim 3. characterized by the fact that the variable-section annular conduit (29) defined between the housing (24) and the nozzle (28) comprises a number of chambers (44) connected in series and defined by respective lateral segments (45) of the nozzle (28) and respective rings (46) projecting from the inner lateral wall (47) of the housing (24); the annular conduit (29) terminating at the top. at the dispersing plate (36), with an upward-flaring chamber (44a).

5) A feed unit (1) as claimed in one of the foregoing claims from 2 to 4, characterized by the fact that said cyclone separating device (23) also comprises a vibratory sieve (48) beneath the bottom portion (26) of the housing (24); and a second output conduit (50) having an inlet in the form of a feedbox (50a) beneath the sieve (48); the sieve (48) being designed to retain and expel from the cyclone device (23) the heavier tobacco particles unsuitable for manufacture of the cigarettes.

6) A feed unit (1) as claimed in one of the foregoing Claims from 2 to 5. characterized by the fact that said first output conduit (35) communicates with the top end of the dropdown channel (9); and by the fact that said second output conduit (50) communicates with the bottom end of the dropdown channel (9).

t, i 7) A feed unit (1) as claimed in claim 6, characterized by the fact that said first output conduit (35) terminates inside a bin (6), immediately upstream from a tobacco carding unit (8) at the top end of the dropdown channel (9); said second output conduit (50) terminating at a plate (52) for supplying a conveyor (12) connecting the bottom end of the dropdown channel (9) to the bottom end of the upfeed channel (14) and to said basin (15) located beneath said upfeed channel (14).

8) A feed unit with a tobacco particle separator for cigarette manufacturing machines, substantially as described and illustrated herein with reference to the accompanying drawings.