GB2248011A

GB2248011A - Apparatus for removing foreign bodies from an air stream conveying cut tobacco

Info

Publication number: GB2248011A
Application number: GB9118940A
Authority: GB
Inventors: Heinz-Christen Lorenzen
Original assignee: Koerber AG
Current assignee: Koerber AG
Priority date: 1990-09-06
Filing date: 1991-09-05
Publication date: 1992-03-25
Anticipated expiration: 2011-09-05
Also published as: ITMI912299A0; IT1251379B; DE4028282A1; GB2248011B; GB9118940D0; ITMI912299A1

Abstract

An apparatus for removing foreign bodies from an air stream which conveys cut tobacco in a conveyor line to a cigarette machine and which after one charging procedure is interrupted and is switched on again for the next charging procedure is described. To remove the foreign bodies, a sifting arrangement, preferably a cyclone sitter, is provided in the pneumatic conveying line. <IMAGE>

Description

1 Apparatus for removing foreign bodies from an air stream conveying cut

tobacco The invention relates to an apparatus for removing foreign bodies from an air stream which conveys cut tobacco in a conveying line to a cigarette machine and which after one charging procedure is interrupted and is switched on again for the next charging procedure.

For automatically charging cigarette rod machines with fibrous tobacco, so-called cut tobacco, there are used pneumatic conveying pipes which lead from a delivery point for cut tobacco to a gate of a cigarette machine. If the cigarette machine indicates a need, i.e. if a cut tobacco reservoir in the so-called distributor of the cigarette machine has fallen below a particular level, then a portion of tobacco located in the gate chamber of the charging gate is transferred, usually by opening a base flap, to the distributor, after which the outlet of the gate chamber is closed again. Thereafter, in general another charging procedure begins, for which the pneumatic conveying pipe is connected to a source of low pressure so that suction is applied to the cut tobacco at the delivery point thereof, and this suction conveys the cut tobacco in a stream of conveying air to the gate chamber. Once the portion of cut tobacco accumulated in the gate chamber has reached a particular size, which is established for example by a detector, then the pneumatic system is switched off, for which for example the source of low pressure is cut off from the conveying pipe. The disappearance of low pressure in the conveying pipe has the result that no more fresh tobacco is sucked at the delivery point and transferred to the conveying pipe. The filled gate chamber is now ready, on a demand signal of the cigarette machine, to transfer the portion contained therein to the distributor by opening the outlet, i.e. for example the base flap, after which a new charging procedure begins by activating the pneumatic conveying system, that is to say connecting the conveying pipe to the source of suction air.

It has been found that foreign bodies such as screws, bolts, screwdrivers or the like are found now and again in the cut tobacco and can cause serious damage there if they reach the distributor of the cigarette rod machine. This can have the result that a rod machine, including the filter attachment machine connected thereto in the manner of conveying technology and possibly also trestle filler or packing machine, can break 2 down for a considerable period, which in the case of modern high- performance machines with outputs of up to 10000 cigarettes/min can lead to considerable production losses. It is possible for the damage to be so great because the distributors of conventional cigarette machines contain rollers and conveyor belts provided with pins, pegs or the like. If a foreign body of the type described above enters conveying rollers or conveying belts equipped with pins or pegs, then the pins in these regions are destroyed. The consequence is that the surfaces in the destroyed regions have to be replaced, for which a partial dismantling of the conveying rollers or belts is required, which always means considerable time expenditure.

The object of the invention is to prevent foreign bodies of the type mentioned above from being introduced into a cigarette machine as far as possible.

In accordance with the invention, this is achieved in that a sifting arrangement is arranged in the pneumatic conveying line.

This is preferably a pneumatically operating sifting arrangement which in accordance with a preferred embodiment of the invention may be constructed as a cyclone sifter.

Further constructions and further embodiments of the invention are to be found in the subordinate claims.

The advantage associated with the invention consists in the fact that because the cut tobacco supplied is substantially free of foreign bodies which can cause the damage mentioned above, the level of output of the machines and the downstream machines can be improved, because machine downtimes resulting from the destruction of rollers or conveyor belts equipped with pins or pegs hardly ever occur or no longer occur at all.

The invention is described in more detail with reference to a drawing containing example embodiments, and in which:

Figures la to 1c show a sifting arrangement for foreign bodies having an automatically operating control system for supplied air, Figures 2a to 2c show a sifting arrangement having controlled air supply.

Figure 1 illustrates a pneumatic sifting arrangement 1 in the form of a cyclone, arranged in a pneumatic conveying system for charging a cigarette rod machine (not illustrated), whereof the charging gate and distributor are described in detail for example in US-PS 4 651 758 of the Applicant. As was stated in the introduction, a stream of conveying air conveying and

3 containing the cut tobacco only at times flows through the pneumatic conveying system 2, which leads from the delivery point (not illustrated) for cut tobacco to the charging gate of the cigarette rod machine (similarly not illustrated), while no conveying air containing tobacco passes through the pneumatic conveying system 2 in the intervals between charging.

The cyclone 1 comprises a cylindrical housing 3 into which the pipe section 2a forming one part of the pneumatic conveying system 2 opens, the stream of conveying air with the cut tobacco 4 being guided from a delivery point through this pipe section 2a to the sifting arrangement 1. The stream of conveying air with the tobacco 4 passes from the outlet 2'a into the inlet 2'b of a preferably centrally arranged second pipe section 2b in which it is conveyed to the charging gate of the cigarette machine. Heavy foreign bodies 6 such as screwdrivers 6a or screws 6b fall to the bottom and pass into a receiver 7 in the form of a drawer 8 which has a sieve base 9 with through passages 11 and can be drawn out by a handle 12 during the intervals between charging (Figure 1b), that is to say in which no stream of conveying air containing tobacco streams through the pneumatic conveying system 2. The foreign bodies 6a, 6b can then be removed, while remaining tobacco 4a goes back into the drawer 8. Below the drawer 8 there is a shut-off device 16 in the form of a double-ended piston 17, 18 which can close or release an air line 19 to the sieve base 9. 21 designates a nonreturn valve which allows an air stream to pass only in the direction of the arrow 22, and 23 designates an adjustable choke arrangement.

Figures la, lb and lc illustrate different states of the pneumatic conveying system and associated functions of the shut-off device 16.

In Figure 1, conveying air and tobacco 4 stream in the pneumatic conveying system 2. The air and the tobacco pass out of the outlet 2'a of the pipe section 2a, through the housing 3 in accordance with the arrows 24, into the inlet 2b of the pipe section 2b, with foreign bodies 6a, 6b falling down onto the sieve base 9. The piston 17 is in the upper position, in which it closes the air lines 19, as a result of the low pressure in the housing 3.

Figure lb shows the state of the sifting arrangement 1 after the pneumatic conveying system 2 has been made inactive by cutting off the source of low pressure, as a result of which the low pressure in the housing 3 also disappears. The pistons 17 and 18 have thus sunk to the bottom as a result of their mass, so that the air lines 19 are released. The drawer 8 can now be withdrawn by the handle 12 and the foreign bodies 6a, 6b 1 4 removed. The remaining tobacco 4a is not an obstruction during this. It is returned with the drawer to the housing 3.

Figure lc shows the state of the sifting arrangement 1 after activation of the pneumatic conveying system 2 by connecting the source of low pressure to the pipe sections 2a, 2b, as a result of which low pressure prevails again in the housing 3. This low pressure sucks the piston 17 upwards, although this means that the air in space 25 must be displaced by the lower piston 18. Since the air flows out of this space through the choke arrangement 23 to the outside, the upward suction of the piston lasts for a certain time during which air flows through the air lines 19 and the through passages 11 in the sieve base and conveys away the remaining tobacco 4a (arrow 26), whereupon charging continues in the manner illustrated in Figure 1. During the actual charging, the upwardly sucked piston 17 closed the air openings 19 again, so that no undesired secondary air enters the sifting system.

The variant of the invention in accordance with Figures Za to Zc differs from the embodiment of Figures la to lc in that the shut-off device 116 having the piston system 117, 118 is actively controlled, as a result of which the release and shut-off times can be more precisely defined and controlled. Parts corresponding with equivalent parts in Figures la to lc are designated by the same reference numerals in Figures 2a to 2c, incremented by 100, and are not described again specifically.

To control the pistons 117, 118, there serves an electromagnetic valve 131, having two exciter coils 132, 133, of which 13Z is acted upon via a line 134 by an electrical signal which is emitted by a detector in the gate of a cigarette rod machine when the gate is filled and the pneumatic conveyor system is to be switched off.

The exciter coil 131 is acted upon via a line 136 by an electrical signal when the machine has indicated a need, the gate is thus to be emptied and immediately thereafter charging is to begin again. Placed in line 136 is a delay element 137.

An electrical signal supplied via the line 136 of the exciter coil 133 switches the electromagnetic valve 131 in the manner shown in Figure Za, in which compressed air from a compressed air source 138 passes into the space 139 and out of the space 141 to the outside or to a compressed air sink 142. On the supply of a signal via line 134 to the exciter coil 132, the electromagnetic valve 131 is switched over, after which compressed air is supplied to the space 141, as is illustrated in Figure 2b.

Figure 2a shows the shut-off device 116 with the pistons 117, 118 located in their upper end position in which they keep the supply of air through openings 119 closed. The electrical control signal via line 136 to the corresponding exciter coil 133 of the electromagnetic valve 131 can originate from the cigarette machine or from a low-pressure switch in the pneumatic conveying system. Compressed air passes from the compressed-air source 138 to the space 131 which keeps the pistons 117, 118 in their upper position.

Figure 2b shows the shut-off device 116 in the case of the switchedover electromagnetic valve 131, whereof the exciter coil 132 has received via line 134 a signal which has for example been emitted by a detector in the gate of the cigarette machine or a low-pressure switch on the disappearance of the low pressure in the pneumatic conveying system. Charging has been completed and the stream of conveying air in the pneumatic conveying system has disappeared. The pistons 117 and 118 are in their lower position in which they release the air openings 119, as a result of the pressure on space 141. The drawer 108 can be withdrawn and the foreign bodies 106a and 106b removed. The remaining tobacco 104a can be pushed back with the drawer 108.

Figure 2c shows the situation at the start of a new charging procedure. The signal emitted by the cigarette machine or the low-pressure switch in the pneumatic conveying system at the start of a new charging procedure has, because of the delay time in the delay element 137, not yet reached the exciter coil 133, so that the electromagnetic valve 131 has not yet been switched over and the pistons 117, 118 are still in their lower position. As a result of the low pressure created in the housing 103, air can flow through the openings 119 and through passages ill of the sieve base 109 and convey the remaining tobacco 104a in the direction of the arrow 126 into the upper pipe section (corresponding to 2b in Figure 1c). After expiry of the delay time in the delay element 137, the electromagnetic valve 131 is switched over into the position which can be seen in Figure 2a, whereupon the pistons 117, 118 are pushed upwards and close the air openings 119, so that no more air can flow from below into the housing 103.

It may be advantageous not to completely cover the openings 19 and 119 by the pistons 17 and 117 respectively but to permit a small stream of additional air during normal charging.

6 If the signal indicating the end of charging and coming from the charging gate of the cigarette machine can effect a very rapid switch-over of the pistons 117, 118, then tobacco 104 can be prevented from reaching the sieve base 109. The timer element 137 can then be omitted.

Instead of providing a receiver which receives foreign bodies during the charging and remaining tobacco towards the end of charging (4a, 104a), a receiver may be provided which is constructed as a gate and therefore allows removal of the foreign bodies during the charging, i.e. even before tobacco reaches the gate. The receiver might for example be a chamber of a rotary gate system as is known in principle for example from US-PS 3 265 209 (Figs. 5 and 6) or 3 655 043 (Item 48) of the Applicant. The remaining tobacco reaching the emptied chamber at the end of charging may if necessary then be transferred in the manner described above to the pneumatic conveying system again at the start of the new charging procedure by air streams which may be supplied through special air openings. The arrangement described above, which by itself has inventive status, may also be used with a pneumatic charging system in which conveying air and tobacco are continually conveyed to the cigarette machine, i.e. where the stream of conveying air does not need to be interrupted repeatedly during operation. As a result of sieving out the foreign bodies while maintaining air sealing in the region of the receiver, there is no impairment of the continuously running sifting procedure.

The depositing of remaining tobacco may also be prevented by a secondary air flap in the pneumatic conveying system, through which flap secondary air may be supplied shortly before switching off -the air, so that the supply of tobacco to the sifting arrangement is interrupted.

f 7

Claims

1. Apparatus for removing foreign bodies from an air stream which conveys cut tobacco in a conveying line to a cigarette making machine and which, after a charging procedure, is interrupted and is switched on again for the next charging procedure, characterized in that a sifting arrangement (1) is arranged in the pneumatic conveying line (2).

2. Apparatus according to Claim 1, characterized in that a cyclone sifter is arranged in the pneumatic conveying line (2).

3. Apparatus according to Claim 1 and/or 2, characterized in that the cyclone sifter is constructed as a cylindrical housing 3, in that in the interior of the housing in the vicinity of the wall a section (2) of the pneumatic conveying line operating by means of suction air opens and is continued in the central region of the housing in a further section (2b) in such a manner that the tobacco (4) is guided from the outlet (2'a) of the line conveying to the sifter to the inlet (2'b) of the line conveying away from this sifter freely through the space, with relatively heavy foreign bodies (6a, 6b) being separable off.

4. Apparatus according to one or more of the preceding claims, characterized in that there is at the base of the sifting arrangement a receiver (8, 108) for the foreign bodies (6a, 6b; 106, 106b) from which the foreign bodies may be removed in intervals between charging, and in which or in the vicinity of which channels (9, 11; 109, 111) for introducing an air stream at the start of a new charging procedure are arranged for the purpose of removing remaining tobacco (4a, 104a).

5. Apparatus according to Claim 4, characterized in that the receiver has a sieve base (9, 109).

6. Apparatus according to Claim 4 and/or 5, characterized by an automatically shut-off device (16) for the air stream.

7. Apparatus according to Claim 4 and/or 5, characterized by a shut-off device (116) which is controllable by a control signal released at the start 4 8 or at the end of a charging procedure.

8. Apparatus according to Claim 6 or 7, characterized in that the shutoff device has piston arrangements (17, 18; 117, 118).

9. Apparatus according to one or more of Claims 1 to 3, characterized in that a receiver for foreign bodies is provided which is constructed as a gate for sieving out the foreign bodies separated off during the charging.

10. Apparatus according to one or more of the preceding claims, characterized in that a secondary air flap is provided in the pneumatic conveying system, and through this secondary air flap secondary air is suppliable shortly before the conveying air is switched off, for the purpose of interrupting the supply of tobacco to the sifting arrangement.

11. Apparatus for removing foreign bodies from a tobacco -conveying air stream, substantially as herein described with reference to the accompanying drawings.

Published 1992 at The Patent Office, Concept House, Cardiff Road. Newport. Gwent NP9 1RH. Further copies may be obtained from Sales Branch. Unit 6. Nine Mile Point. Cwmfelinfach. Cross Keys. Newport, NP I 7HZ. Printed by Multiplex techniques lid, St Mary Cray. Kent.