GB2086205A

GB2086205A - A rod-making machine and a heater therefor

Info

Publication number: GB2086205A
Application number: GB8126442A
Authority: GB
Original assignee: Molins Ltd
Current assignee: Mpac Group PLC
Priority date: 1980-09-06
Filing date: 1981-09-01
Publication date: 1982-05-12

Abstract

A cigarette or filter rod making machine has a heater which may be a heated folder 18, which remains in contact with the rod 30 when the machine stops. Air flow passages 21 are provided in or adjacent the heating element to direct air onto the rod when the machine stops so as to prevent scorching. The heating element may be automatically switched off when the machine stops and the air flow continued for a predetermined time. A temperature sensor may be provided for controlling the power supply to the heating element and maintaining a desired temperature of the heater or the rod itself. The control may be linked to the speed of the machine. <IMAGE>

Description

SPECIFICATION A rod-making machine and a heater therefor This invention is concerned with heaters for continuous rod making machines, especially cigarette making machines and cigarette filter making machines, in which a continuous wrapper is secured around a filler stream (e.g. of tobacco) with the aid of an adhesive between the overlapping edges of the wrapper, wherein the heaters heat the seam which is thus formed so as to set the adhesive. A typical adhesive used for this purpose is PVA (polyvinyl acetate).

For high speeds of operation (e.g. 350 metres per minute or higher) a considerable amount of heat must be transferred to the rod seam to set the adhesive. One or more rod heating devices may be used for that purpose; however, since their length is limited by a need for a compact iayout, high temperatures are required for adequately setting the adhesive at high speeds of operation.

On the other hand, when the machine is first started, it runs initially at a relatively low speed at which a lower temperature is adequate and may in fact be essential to avoid scorching the wrapper web which is normally a thin paper. When a machine stops, it is common to arrange for the heater or heaters to be automatically lifted away from the rod to avoid scorching; it is possible to arrange that the power supply to the heater or heaters is automatically switched off when the machine stops, but that alone may be insufficient to avoid scorching because the heater temperature does not drop instantaneously in view of the mass of the heater.

According to the present invention there is provided a heater for a continuous rod making machine of the cigarette industry, comprising a heating element and air flow passages formed in or adjacent to the heating element to direct air onto the rod when the machine stops so as to prevent scorching.

According to the invention there is also provided a rod-making machine, with a heater which is arranged to remain in contact with the rod when the machine stops (and possibly also in contact with the garniture tape in the event that the heater is a final folder as described below), wherein air flow passages are formed in or adjacent to the heater to direct air onto the web (and possibly onto the garniture tape if necessary) when the machine stops, so as to prevent scorching.

If the power supply to the heater (assuming that it is an electrical heater) is automatically switched off when the drive to the machine is discontinued, the supply of air may be arranged to stop after a predetermined interval long enough to allow the heater temperature to fall to a safe level.

Alternatively, power may continue to be supplied to the heater when the machine stops (in which case the air supply would also be maintained throughout the stoppage) so that the heater is ready to resume its heating function as soon as the machine re-starts.

The heater or heaters may be associated with temperature sensing equipment to take the temperature of the heater or heaters or of the rod as it emerges from the heaters, with provision for controlling the power supply to the heater or heaters to maintain a desired temperature, possibly variable according to the speed of the machine.

One of the heaters in a machine according to this invention may comprise the final folder, which normally has no provision for lifting it automatically when the machine stops. The provision of air according to this invention allows a final folder to be used as a heater at a high temperature; without the air, the final folder can be heated but, owing to its mass, it could not be used normally at a high temperature since it would not cool down sufficiently quickly to avoid scorching when the machine stops.Similarly, a heater downstream of the final folder may, with benefit, be kept in position adjacent to the rod when the machine stops, by the use of air in accordance with this invention, thus allowing the machine to make a complete rod immediately it re-starts, where normally in the past the lap has not been sealed so as to form a complete rod until the heater or heaters are lowered onto the rod.

An example of a machine according to this invention is shown in the accompanying drawings.

In these drawings: Figure 1 is a diagrammatic view of the relevant part of the machine; Figure 2 is a section through the wrapper web and filler on the line II--II in Figure 1; and Figures 3 and 4 are fragmentary sections on the lines Ill-Ill and lV-lV in Figure 1 respectively.

Figure 1 shows a cigarette making machine including a perforated tape 10 which carries a cigarette filler stream 11 onto a continuous wrapper web 12. A woven garniture tape 13 carries the wrapper web through the rod-forming section of the machine. The arrangement may be generally in accordance with the Molins Mark 8 or Mark 9 cigarette making machine.

The tape 10 returns around a pulley 14 adjacent to which there is a device 1 5 comprising a shoe which helps to remove the tobacco from the tape, and a tongue which compresses the tobacco stream while shaping it towards the cross-section of the finished cigarette rod. At this stage the edge portions of the wrapper web 1 2 extends upwards. After leaving the device 15, one edge 1 2A of the wrapper is folded down onto the filler stream by a first folder 1 6. As the wrapper leaves the first folder 16, its cross-section is as shown in Figure 2; the second edge portion 1 2B still projects upwards so that a strip of adhesive can be applied to its inner surface by an adhesive applicator 1 7 (Figure 1).

A final folder 1 8 having the cross-section shown in Figure 3 then folds down the second edge 1 2B of the wrapper. This folder 18 is heated by a heating element 19 contained in a longitudinally extending bore in the folder.

Although the purpose of heating this folder is to heat the adhesive, the folder must necessarily also engage the right-hand side of the garniture tape as seen in Figure 3. Thus both the garniture tape and the edge portion 1 2B of the wrapper are in danger of being scorched when the machine stops, assuming that the folder operates at a high temperature during high-speed operation. To avoid scorching, air is supplied to a longitudinally extending manifold 20 in the folder 18, and is directed through numerous spaced passages 21 extending to the garniture tape and/or to the edge portion 1 2B of the wrapper. It will be understood that the passages 21 may for that purpose be at various inclinations to the vertical.

The temperature of the folder 1 8 may be detected by a thermocouple secured in or on the folder, or by a platinum resistance bulb in order to control the power input to the heating element 1 9 to maintain the folder at a substantially constant temperature or at a temperature dependent upon the speed of operation of the machine.

Alternatively, the temperature of the top of the rod 30 as it emerges from the final folder 18 may be detected by an infra-red device.

Final heating of the adhesive to secure the overlapping edges of the wrapper is achieved by means of a heater 22. This is a relatively narrow low-mass device including an electrical heating element 23 and having a narrow lower edge for contacting the top of the rod in the region of the seam. The surface of the heater touching the rod is formed by a wear-resistant strip 24. When the machine is switched off, there is provision for automatically lifting the heater 22 to avoid scorching the paper. Alternatively, there may be pipes for blowing air onto the paper adjacent to the sides of the heater so as to push the paper away from the heater, thus allowing the heater to remain in position when the machine stops. As already mentioned, when the drive to the machine is switched off, the air supply would be automatically switched on, either permanently or for a predetermined period of time if the power supply to the heating element 23 is automatically switched off.

With reference to Figure 3, compressed air is supplied to one end of the manifold 20 (when required) via a solenoid valve. The other end of the manifold may be closed by a plug which may provide a small vent to atmosphere.

If the garniture tape is substantially nonpervious, the air flowing out through the passages 21 may produce an air bearing effect, as well as cooling the garniture tape and paper edge by carrying away heat.

Claims

1. A heater for a continuous rod making machine of the cigarette industry, comprising a heating element and air flow passages formed in or adjacent to the heating element to direct air onto the rod when the machine stops so as to prevent scorching.

2. A heater according to claim 1, comprising means for deactivating the heating element when the rod making machine is stopped, and means for stopping the air flow a predetermined time later.

3. A heater according to claim 1 or claim 2, comprising a temperature sensor and means for controlling the power supply to the heater in dependence upon the temperature sensed to maintain a desired temperature.

4. A heater according to claim 3, wherein the temperature sensor is arranged to sense the temperature of the heater.

5. A heater according to claim 3, wherein the temperature sensor is arranged to sense the temperature of the rod as it emerges from the heater.

6. A heater according to claim 3, 4 or 5, wherein the power supply is additionally controlled in dependence upon the speed of the rod making machine.

7. A heater for a continuous rod making machine, substantially as herein before described with reference to the accompanying drawing.

8. A continuous rod making machine comprising a heater according to any one of the preceding claims.

9. A continuous rod making machine according to claim 8, wherein the heater is a final folder for folding a web around a filler to form a continuous rod.

1 0. A continuous rod making machine substantially as hereinbefore described with reference to the accompanying drawing.