MXPA99005549A - Apparatus and process for threshing tobacco - Google Patents

Abstract

Apparatus for threshing tobacco comprises rotatable stripping means (3) and a feeder comprising a pair of co-operating counter-rotatable elements (1, 2) for delivering tobacco leaves to the stripping means. The feeder and the stripping means are arranged such that, in use, the tobacco leaves experience shearing forces as they pass from between the counter-rotating elements to the rotating stripping means which forces at least partially strip the lamina from the stem.

Description

APPARATUS AND PROCESS FOR. THE TOBACCO THREAD FIELD OF THE INVENTION This invention describes an apparatus and a process for threshing tobacco.

BACKGROUND OF THE INVENTION In the tobacco industry, it is well known that in order to process the tobacco into a form suitable for use in the manufacture of products, the tobacco leaf must have the central rib of the remainder of the tobacco leaf removed. The separation is sometimes done by hand, but is more common through the use of a threshing machine.

The threshing machines for tobacco, now in use, differ somewhat from those described by Du Brul in the US document 209,801 dated November 12, 1878, and designed to thresh tobacco for use as a cigar stuffing. Ref .: 30582 In the current technique, the most common process for threshing tobacco leaves consists of: 1. Feed the tobacco leaves inside the top of a threshing mill. The leaves are separated by the action of a rotating element, which has teeth that come out radially, until they are small enough to pass within a fixed mesh in the bottom of the mill. 2. The threshed sheets are then classified by the use of an air flow in a vertical tower. Then the lighter materials, free of stem, rise with the air flow and move away from the threshing process. The heavier material, that is to say the one containing the stems, goes down through the air by the force of gravity down the tower. 3. The heavier material, ie the one containing the stems, is passed to a second threshing mill, and the process is repeated.

The overall threshing process usually has between 4 and 6 threshing and grading phases, before the entire sheet is removed from the central rib.

The most common form of a tobacco mill is described in U.S. Patent 2,760,492 and Bonner et al. In U.S. 3,141,485.

US Pat. No. 2,962,029 (McCashen) discloses a tobacco threshing machine having a single rotary threshing element mounted inside a rotating drum.

Several documents describe machines which include two or more rotating threshing elements, inside a single machine with various claims for improvements on existing individual rotor threshers. In the US patents 3,126,014 and 3,696,817; Bonner et al describes a thresher that contains two or more rotating elements in a cascade, placed in baskets fixed in a conventional manner. In the North American patent 3,706,314; Smith describes a machine with two rotating elements that have radial teeth that mesh with rotating elements consisting of discs. None of these three machines is commonly in use.

Wochnowski in GB 1,077,410 and Johansson et al in US Pat. No. 3,229,698 disclose threshers containing two or more mills with fixed baskets containing inside a separation tower by means of air. In the first of these, threshers are conventional in their form. In the second, the thresher shaft is mounted vertically instead of horizontally. The machines of the second form are commercially used, but these appear to be less efficient than those of the conventional type and are used mainly where the floor space is very much in demand.

In GB 301,239 Phillips discloses a machine for separating tobacco leaves in which the sheet is separated from the stem by the passage of the sheets between pairs of anti-rotation brushes and rollers which roll at different speeds. The leaves are subjected to tensile forces which separate the blade from the stem.

Dahlstrom et al in US Pat. No. 2150493 and in US Pat. No. 2157791 teaches a device for disintegrating tobacco leaves which includes a pair of counter rotation rollers for feeding tobacco leaves to a rotating cylinder having a series of protruding teeth. However, all the separation of the stem sheet occurs at a distance from the rollers at a point where the teeth on the cylinder pass through a series of intermeshing discs.

In US Pat. No. 2,789,564 (Hunter) and in US Pat. No. 4805643 (Tetaka) an apparatus is described in which tobacco is supplied to a relatively large toothed rotor via an opening located above the rotor. Hunter additionally employs smaller rotors that engage with the larger rotor to thresh the tobacco leaves.

EP-A 0135048, describes a system that is used with a tobacco threshing machine, for the control of the size of the sheet.

In the pharmaceutical and food industries, threshing is traditionally used to obtain the seeds or fruits of the harvest free of the voluminous material of the plant. This is normally given as a part of the harvest.

The threshers used in the legume crops use axial flow threshing system as described by Looker et al in GB 1,396,931 and 1,396,932. Here the mass of the crop is transferred into a large rotating drum constructed of mesh panels. Inside the drum there are a number of whisking elements.

According to Looker et al, these works are designed so that the mass of the crop flows in a route such that several impacts occur. These impacts are enough to open the pod of the legume and release the seeds contained inside.

DESCRIPTION OF THE INVENTION The present invention describes an apparatus and a process for threshing tobacco, which has significant advantages over known techniques.

Accordingly, the present invention provides an apparatus for threshing tobacco comprising rotary separation means and a feeder comprising a pair of counter-rotating co-operative elements that supply the tobacco leaves to the separation means, the feeder and the means of The separation has an arrangement such that, in use, the tobacco leaves undergo a force cut as they pass between the rotary counter elements towards the rotary separation means whose forces at least partially separate the sheet from the stem.

The separation means preferably comprise radially extended arms. The arms may be in the form of continuous plates or separate teeth (which may be straight, bent or curved), and may include the parts which are capable of cutting tobacco leaves or being able to pierce and tear through. of the leaves.

The elements also preferably comprise radially extended arms which may also be in the form of straight, curved or bent plates or of separated teeth, and which optionally include parts which are capable of cutting the tobacco leaves. Alternatively, the feeding elements may comprise a pair of rollers, or may consist of a flexible membrane wound around a frame which allows varying amounts of sheets to be fed.

The arms can be flexible, not flexible or a combination of flexible and fixed components.

The rotating elements and the separation means can take the same figure and can be of the same shape and size, differing only in their functions which are dictated by their respective positions in the apparatus.

The separation means and the feeder are arranged at a relatively short distance between them, in order to subject the tobacco to cutting forces which at least separate the sheet from the stem. Preferably, the distance between the outermost portions of the two elements in the feeder is less than 150 mm, and the distance between the outermost portions of each of these elements and the outermost portions of the separation means is less than 100 mm The cutting forces are experienced by the tobacco leaves that are directed from the feeder to the rotary separation means. The tobacco leaves are preferably supplied to the rotating separation means substantially along a radius of the axis of rotation of the separation means. The sheet is separated from the stem in the region where they pass to be moved under the influence of the feeder to be moved by means of separation and, as a skilled person can appreciate, the exact position of this region varies depending on the particular configuration of the apparatus and the rate of rotation of its various rotating components. The cutting force can be considered, at least under certain circumstances, which rises from the action of the separation means on one part of the sheet while the feeder holds another part of the sheet.

Preferably, the teeth mesh with each other, where the arms of the separation means and those of the elements consisting of separate teeth. With such an arrangement, the separation of the sheet from the stem is effected, to some extent, by the interaction of the separation means and the feeder. When the teeth mesh with each other, the distance between the teeth passing each other is typically less than 100 mm.

The apparatus preferably comprises a rotating drum in which the separation means and the feeder are arranged. The drum can be generally cylindrical and its walls can be solid. However, the drum preferably comprises a mesh (for example, in its walls) which allows at least a part of the separated tobacco to be distributed in the drum. The mesh can form all or only a part of the side walls of the drum.

The drum preferably incorporates protruding rings internally to direct the tobacco leaves towards the feeder elements. As the drum rotates, the rings gather the tobacco leaves so that the leaves travel around the drum until they fall (preferably only under the influence of gravity) inside the feeder. The position of the feeder inside the drum and / or the speed of rotation of the drum are adjusted in order to ensure that an appropriate amount of the tobacco leaves is supplied to the feeder when the drum rotates.

To assist the transfer through the drum, an additional rotatable or fixed element runs down the drum parallel to the separation means, it can be used to delay the tobacco leaving the separation systems. The tobacco thus retained is then able to fall under the influence of gravity on a lower part of the surface of the drum. Preferably the tangential speed of the additional rotary element is similar to that of the drum (i.e., ± 50% of the drum speed) (- and it is also preferred that the additional rotating element has a direction of rotation opposite to that of the drum.

The separation means and the elements rotate preferably around axes which are parallel to the axis of rotation of the drum. Preferably, the axes of rotation are either substantially horizontal or are inclined from 0 ° to 10 ° (more preferably from 2 ° to 6 °) with respect to the horizontal.

The separation means and the elements can converge to approach the exit end of the drum to take into account the load reduction that results from the small particles that are cast from the main flow. This also allows the amount of threshing that takes place to increase towards the exit end of the drum. This convergence can be realized by varying the diameter of the separation means and / or the elements along their length. By adopting this method, an additional effect increases the tangential velocity of the limbs of the arm as the diameter increases and this has an effect on the threshing characteristics.

The diameter of the drum is typically within the range from 300 to 2500 mm, preferably from 900 to 1800 mm.

The diameters of the separating means and the elements (defined by the end of any of the radially exiting arms) are typically from 5 to 50% of the diameter of the drum.

The tangential speed of the drum is preferably within the range from 0.04 to 0.5 m / s with the tangential velocity of the separation means and the elements that are from 3 to 250 times (preferably from 10 to 100 times) higher than those of the drum.

The rotating components of the apparatus (different from those of the drum), can be run at synchronous speeds to realize an authentic gear between the separation means and the rotating elements. Alternatively, the rotating components can be run such that they have different tangential speeds, thus, the deviation actions between the various rotating components are established. The selection of the rotational speed and the mode of operation depend on the design of the rotating components and the protrusions of the drum used and this at the same time depends on the nature of the sheets that are threshed and on the required specifications of the threshed material.

The conductor used for feeding the material of the sheets within the drum can be constructed so as to move the feeding point of the sheets inside the drum. This can be used to control the amount of threshing that is given to the leaves.

A conductive device open at the top can also be incorporated to remove the larger pieces of the free sheet from the rest of the sheet material. The action of the rotating components of the apparatus can be arranged to release the material from the sheets through the air. The lighter stem free blade is quickly retained and lands on the driver while the heavier parts containing stem are thrown over the driver's dome and continue around the drum for additional threshing. This avoids unnecessary damage to the larger pieces of the stem-free blade.

Air currents that are directed into the drum can be used to assist this separation.

In another embodiment, the present invention describes a process for threshing tobacco which comprises supplying tobacco leaves to a feeder comprising a pair of counter-rotating co-operative elements and feeding the sheets from the feeder to the rotary separation means. so that the sheets experience loss of forces when they pass between the rotating elements to the separation means which at least partially force the separation of the sheet from the stem. The process is conveniently carried out by using the apparatus of the invention.

The tobacco leaves which are threshed in the apparatus and process of the invention preferably have a moisture content of between 5 and 35% by weight and can be conditioned before threshing.

The apparatus of the invention may comprise more than one (for example two) separation means and the extra separation means may be provided by one or more additional rotating elements. These additional elements can carry out a degree of threshing and / or cutting of the tobacco leaves and can participate in the supply of the untrimmed or partially threshed sheets to the feeder and / or the separation means. The apparatus may also comprise additional rotating elements which may only act to direct the material of the sheets within the separation means.

The invention will now be described, by way of example only, and with reference to the accompanying drawings, where: Figure 1 shows a cross-section through an apparatus, in accordance with one embodiment of the invention; Figure 2 shows a cross-section through an apparatus, in accordance with another embodiment of the invention; Figure 3 shows a cross-section through an apparatus, in accordance with a further embodiment of the invention; Figures 4 and 5 show perspective views of separation means suitable for use in the apparatus of the invention; Figure 6 shows perspective views of three types of arm (or teeth) for use in the apparatus of the invention; Figure 7 shows a plan view of another arm for use in the separation means of the invention; Figure 8 is a side view of other separation means suitable for use in the apparatus of the invention; and Figure 9 is a flowchart of a preferred process for threshing tobacco by use of the invention.

With reference to Figure 1, the drum 6 rotates about a substantially horizontal axis in a counter-clockwise direction. A series of rising rods (or rings) 7, are joined to an inner surface of the drum 6. The function of the rods 7 is to move the tobacco leaves towards the side of the drum 6. The sheets are then picked up by the elements against rotating co-operative 1 and 2 which form a feeder for the leaves. Elements 1 and 2 comprise arms that extend radially, 2a which run the full length of the drum. In the embodiment of the invention shown in figure 1, the arms la, 2a are as described in figure 5. The sheets are forced between the elements 1,2 where some trilling or cutting of the leaves can take place. The sheets are supplied from between the elements 1,2 within the separation means 3 which have the arms 3a. The separation means 3 rotate in the same direction as the drum of the figure, that is to say counter-clockwise, although this can rotate in the opposite direction. This is in the region of supply of the sheets from the elements 1,2 to the arms 3a of the separation means 3 that in most of the threshing takes place like the leaves which are still partially supported by the elements 1,2 they are torn by the cutting action of the separation means 3. The separation means 3 can also act to cut the leaves of some extensions. The sheets threshed by the separation means 3, exclude any part of the threshed sheets which may have broth to the bottom of the drum 6, is collected between the separation means 3 and the element 4 which is additionally located around the drum 6 (in the direction of its rotation) and are forced towards the second separation means 5 and create a second cutting zone inside the drum. The rotational direction of the rotating elements 1,2,4 the separation means 3,5 and the drum 6 are indicated by the broken arrows.

Another embodiment of the invention is illustrated in Figure 2. Here the sheets are transported to the side of the drum 10 on the rods 11 by the rotational movement of the drum 10 (counterclockwise in the figure). The sheets are then dragged into the opening between the rotating counter elements 12 and 13 which run the length of the drum 10 and co-operate to act as a feeder which directs the sheets into the separation means 14. The main function of the separation means 14 is to cut or tear the free sheet from the stems of the leaves. The separation means 14 and the elements 12, 13 have the bent arms 14a, 12a, 13a and are of the general design shown in Figure 4. An alternative design of the arms 14a, 12a, 13a is illustrated in Figure 7.

In Figure 3, the drum 20 rotates counterclockwise, in use the rods 21 transfer tobacco leaves to the rotary elements 22 and 23. The differently designed arms 22a and 23a of the elements 22 and 23, respectively, feed the sheets to the separation means 24 which have arms 24a. The arms 24a engaged with the arms 23a. The fixed element 25 traps the milled tobacco and its leaves in the separation means 24 and allows them to return to the inner surface of the drum 20.

With reference to Figure 6, the arms Ia, 2a of the feeder and / or the separation means may have a flat edge. Alternatively, as shown in the arms 23a, 24a, the most protruding edge of the arms can be decreased by one point and can taper from one end to a narrower end along the drum direction in order to assist in the cutting of the leaves.

The process of the invention can be run continuously or as a batch process. For continuous operation, the tobacco leaves are fed into one end of the drum, the sheets are thickened through the length of the drum and the threshed sheets which have not passed through the drum (for example through the meshes in their meshes). walls) leave the drum to the other end. The passage of the sheets from one end of the drum to the other can be done by tilting the drum and, optionally, also the rotating components of the apparatus at an angle with respect to the horizontal or by a helical screw 15 in the apparatus, as shown in FIG. Figure 8. The helical screw can constitute the separation means and / or the rotating elements of the apparatus.

Alternatively, the transfer of the sheet material under the drum can be affected by arranging the helical rods on the inside of the drum or the transfer can be caused by air currents acting on the sheet material.

A preferred process for use with the invention comprises recycling the threshed tobacco as shown in the flow chart of Figure 9. Where the drum is constructed from the sections of the mesh, the entire device acts in the form of a thresher and a strainer in a single machine. In this way it can be incorporated into a global process as shown in Figure 9 or it can be used as a part of a conventional process line. With reference to Figure 9, the tobacco leaves are first conditioned and then threshed using the process and apparatus of the invention. Two fractions are obtained after threshing; (i) the tobacco passed through the meshes with the smallest pieces of the threshed tobacco which have passed through a mesh (preferably on the side wall of a drum of the apparatus) and (ii) the large tobacco with the larger pieces retained in the apparatus. The snuff passed through the meshes, are composed of the smallest particles of the threshed leaves, this is subjected to a conventional air separation and the "heavy" and "light" fractions are directed to drying or further processing in the conventional way . The large pieces of tobacco are also subjected to separation by means of air and the light pieces are sent to drying or further processing. Nevertheless, the heavy part is returned directly to the threshing phase of the process to further separate the blade from the stem. This type of process is described in detail in our European patent application described number 96309188.9 which was registered the same day as this application and has the title of "Method and apparatus to process tobacco".

As mentioned above, the surface of the drum used in the apparatus of the invention, which is preferably cylindrical, can be either solid or comprised of meshes.

Where the surface of the drum is solid, the entire mass of the sheets travel the full length of the drum passing through the separation means.

Where the surface of the drum consists of meshes, the smallest threshed particle particles are distributed in the drum without having to traverse the full length of the drum. This means that the smaller particles avoid additional unnecessary impacts and suffer less damage as a result of they have also been threshed. Larger particles not able to pass through the meshes travel the full length of the drum and exit from the drum end. The meshes have a size of fabric appropriate for the requirements of the desired end products.

Where the process requires an improvement in the efficiency of the mesh, the length of the elements and the separation means may be less than the full length of the drum. This allows extra casting to be carried out before, after or before and after the threshing zone by appropriate location of the elements and the separation means within the drum. The stem free blade can be previously removed before threshing, eliminating unnecessary damage to it and the amount of clean stem that is removed through the mesh after threshing can be increased.

The apparatus, where the surface of the drum consists of meshes, can be used as threshing filler for use in cigars. The filling which is small enough to be used in the manufacture of cigar pieces passes through the drum mesh. Too large material is recycled into the drum feed end, as shown in Figure 8, and the threshing process is repeated until the pieces are small enough to pass through the meshes.

The following non-limiting examples further illustrate the invention.

Example 1 A tangled tobacco leaf sample, with a moisture content of 27.8% by weight, was threshed for 80 seconds in a batch inside a machine configured as shown in Figure 2. The tangential velocity of the drum was 0.18 m / s. The separation elements, with arms as shown in figure 7, where there is a rotation with a tangential velocity of 1.5 m / s and the feeding elements with arms as shown in figure 4, where there is a rotation with a tangential velocity of 1.0 m / s.

The machine has a drum diameter of 1524 mm, the diameter of the separation means (including its arms) is 455 mm. And each of the elements of the feeder (which includes its arms) is 305 mm. The opening between the arms of the feeder is about 100 mm and the margin of the arms of the separation means is located about 20 mm apart from the arms of the elements of the feeder. 60.3% of the total incoming sheet was separated as stem free sheet, and the sheet contained 83% more than that of 12.7 mm (1/2") and 6% smaller than that of 6.35 mm (1/4") .

Example 2 A tangled tobacco leaf sample, containing a moisture of 27.2% by weight, was threshed for 30 seconds in a batch within a machine described in Example 1. The tangential velocity of the drum was 0.17 m / s. The separation elements, with arms as shown in figure 7, had a rotation with a tangential velocity of 3.0 m / s and the feeder elements with arms as shown in figure 4, had a rotation with a tangential velocity of 2.0 m S. 73.6% of the total incoming sheet was separated as stem free sheet and the sheet contains 88.2% more than 12.7 (1/2") and 3.3% less than 6.35 mm (1/4").

Example 3 A tangled tobacco leaf sample, which contains a moisture of 20.7% by weight, was threshed for 20 seconds in a batch within a machine described in Example 1.

The tangential velocity of the drum was 0.17 m / s. The separation elements, with arms as shown in figure 4, had a rotation with a tangential speed of 2.95 m / s and the feeder elements with arms as shown in figure 1, had a rotation with a tangential speed of 1.97 m / s. 75.9% of the total incoming sheet was separated as stem free sheet and the sheet contains 87.5% more than 12.7 (1/2") and 3.9% less than 6.35 mm (1/4").

Example 4 A tangled tobacco leaf sample, containing a moisture of 25.2% by weight, was threshed for 20 seconds in a batch within a machine described in Example 1. The tangential velocity of the drum was 0.18 m / s. The separation elements, with arms as shown in figure 7, had a rotation with a tangential velocity of 3.94 m / s and the feeder elements with arms as shown in figure 4, had a rotation with a tangential velocity of 1.53 m / s. 64.4% of the total incoming sheet was separated as stem free sheet and the sheet contains 88.5% more than 12.7 (1/2") and 3.4% less than 6.35 mm (1/4").

The advantages of the apparatus of the invention over conventional threshers can be summarized as follows: (a). The large pieces of the free sheet can be produced as they do not have to be reduced in size to pass through the threshing basket. (b) Less dust is produced from the leaves since the grinding of the leaves between the grinding rotor and the surface of the machine does not occur. (c). The total plant to complete threshing of the leaves is reduced by up to 90% of the sheet can be released from the stem in a single step, compared to less than 70% for a conventional thresher.

It is noted that in relation to this date, the best method known to the applicant, to put into practice the aforementioned invention is that it is clear from the manufacture of the objects to which it refers.

Having described the invention as above, property is claimed as contained in the following:

Claims (14)

1. An apparatus for threshing tobacco characterized in that it comprises rotating separating means and a feeder comprising a pair of counter-rotating elements co-operative for the supply of tobacco leaves to the separation means, the separation and feeding means are arranged in such a way that , in use the tobacco leaves experience loss of forces when passing between the rotating elements towards the rotary separation means whose forces at least partially separate the blade from the stem.

2. An apparatus according to claim 1, characterized in that the separation means comprise radially extending arms.

3. An apparatus according to claim 1 or 2, characterized in that the elements comprise radially extending arms.

4. An apparatus according to claim 2 or 3, characterized in that the arms are of the shape of plates or teeth.

5. An apparatus according to claim 2 or 3, characterized in that the arms are flexible.

6. An apparatus according to claim 4 or 5, characterized in that the arms of the separation means and the arms of at least one of the elements are engaged.

7. An apparatus according to any of claims 1 to 6, characterized in that the separation means and the feeder are arranged inside a rotating drum.

8. An apparatus according to claim 7, characterized in that the drum comprises a mesh which allows at least a part of the separated sheet to pass to the drum.

9. An apparatus according to claim 7 or 8, characterized in that the drum comprises protruding rods internally for directing the tobacco leaves towards the feeder.

10. An apparatus according to any of claims 7 to 9, characterized in that the separation means and the elements rotate around axes which are parallel to the axis of rotation of the drum.

11. An apparatus according to claim 10, characterized in that the axes of rotation are substantially horizontal.

12. An apparatus according to any of claims 1 to 11, characterized in that they comprise two rotating separation means.

13. An apparatus according to any of claims 1 to 12, characterized in that it additionally comprises means for reducing the speed of the tobacco leaves after they leave the separation means.

14. An apparatus according to claim 13, characterized in that said means for reducing the speed of the tobacco leaves is either rotatable or fixed and has its axis aligned substantially parallel to the axis of rotation of the separation means.