Method for casting an alkaloid material including changing a height of a casting blade in response to variations in sensed movable support height

Abstract

The invention relates to a method to cast a sheet (2) of a material containing alkaloids, the method comprising: Providing a container (6) having an aperture; providing a casting blade (9); Providing a movable support (3) running below the aperture of the container (6); Filling the container (6) with slurry (5); Casting the sheet (2) of tobacco material containing alkaloids material by means of the casting blade (9) onto the movable support (3); Sensing variations in a height of the movable support (3); and changing a height of the casting blade (9) if such variations in the height of the movable support (3) are present.

Claims

1. Method to cast a sheet of a material containing alkaloids, the method comprising: Providing a container having an aperture; providing a casting blade; Providing a movable support running below the aperture of the container; Filling the container with slurry; Casting the sheet of tobacco material containing alkaloids material by means of the casting blade onto the movable support; Sensing variations in a height of the movable support, wherein sensing variations in the height of the movable support includes positioning a sensing surface in contact to the movable support; and Changing a height of the casting blade based on the sensed variations in the height of the movable support.

2. The method according to claim 1, including: Selecting a height of the casting blade with respect to a reference plane; Selecting a height of a portion of the movable support located below the casting blade with respect to the reference plane.

3. The method according to claim 1, wherein the casting blade includes a tip and wherein the method further comprises sensing the height of the casting blade and includes changing a height of the tip of the casting blade.

4. The method according to claim 1, including positioning two sensing surfaces on the movable support at two opposite lateral sides of the cast sheet.

5. The method according to claim 1, including: Translating the movable support below the aperture by means of a roller; Positioning the container on a top portion of the roller.

6. The method according to claim 5, wherein providing the casting blade adjacent to the container includes providing the casting blade with a tip forming an angle comprised between about 5° and about 10° with a top most point of the roller.

7. The method according to claim 1, wherein changing the height of the tip of the casting blade includes: Sending signals relative to variations in height of the movable support to a motor; Raising or lowering the tip of the casting blade by means of the motor according to the received signals.

8. The method according to claim 1, including: Delaying the step of changing the height of the tip of the casting blade with respect to the step of sensing variations in height of the movable support.

9. The method according to claim 1, wherein positioning a sensing support surface in contact to the movable support includes positioning a sensing support surface downstream the casting blade in the direction of motion of the movable support.

10. The method according to claim 9, wherein positioning a sensing support downstream the casting blade includes positioning the sensing support surface at an angle comprised between about 15° and about 30° with a top most point of the roller.

11. The method according to claim 1, including: Exerting a force by the sensing surface onto the movable support.

12. The method according to claim 11, including: Varying the value of the force depending on the desired sensitivity.

13. The method according to claim 1, including: Drying the cast sheet.

14. The method according to claim 1, including: Rolling the cast sheet into a bobbin.

Description

(1) Further advantages of the invention will become apparent from the detailed description thereof with non-limiting reference to the appended drawings:

(2) FIG. 1 shows the basic principle of how to cast a sheet of alkaloids containing material according to the state of the art in a schematic perspective view;

(3) FIG. 2 is a first embodiment of how to produce a cast sheet of alkaloids containing material with homogeneous thickness in a schematic view from the side;

(4) FIG. 3 is a second embodiment of how to produce a cast sheet of alkaloids containing material with homogeneous thickness in a schematic view from the side; and

(5) FIG. 4 is a third embodiment of how to produce a cast sheet of alkaloids containing material in a schematic view from the side.

(6) In FIG. 1 a casting apparatus 1 for casting sheets 2 of alkaloids containing material from a slurry 5 as presently used in the state of the art is shown in a partial, schematic perspective view. Preferably, sheet 2 is a homogenized tobacco sheet.

(7) Casting apparatus 1 includes a movable support 3, one or more rollers 4, a casting box 6 adapted to contain slurry 5 and a casting blade 9.

(8) Using the casting apparatus 1, a thin sheet 2 of alkaloids containing material is cast on the flexible, thin movable metal support 3 that is presently made out of a thin band of steel. The band of steel 3 is closed to form a loop, so that the thin band of steel 3 forms a structure that is similar to a conveyor belt.

(9) It is noted that in FIG. 1 only a part of the complete casting apparatus 1 is shown, namely the part where the casting of the sheet 2 of alkaloids containing material is done. The conveyor belt 3 may show a significant length so that the sheet 2 of alkaloids containing material that is initially present on conveyor belt 3 in a viscous or pasty form has sufficient time to dry so that it can become mechanically stable and can be pulled off the conveyor belt 3. When being pulled off the conveyor belt 3, the sheet 2 of alkaloids containing material has to be mechanically self-sustaining. The thus created sheet 2 of alkaloids containing material can be wound up onto a bobbin that can be easily stored or that can be transported to other production machine or even another production facility.

(10) The conveyor belt 3 is supported at both ends (only one is shown in FIG. 1) by rollers 4 that typically show a radius of about 30 centimetres. However, different sizes are possible as well. In FIG. 1, only the left roller 4 is visible, where roller 4 is an actively driven roller, so that roller 4 is able to move the conveyor belt 3 together with the deposited sheet 2 of alkaloids containing material on top.

(11) Although not shown in FIG. 1, some intermediary supporting rollers that are typically of a smaller size may be used, so that a somewhat horizontal plane can be realized for the upper surface of conveyor belt 3, even if the conveyor belt 3 has a significant length. The roller at the other end may be either actively driven or passively driven. The intermediary supporting rollers (not shown) are usually not actively driven, although it is possible that at least some of those supporting rollers are actively.

(12) Furthermore, it is possible to provide the casting apparatus 1 with heating devices (not shown) so that the cast sheet 2 of alkaloids containing material dries faster.

(13) This can be done by electrical heating elements or some gas flames that heat up appropriate areas of the conveyor belt 3 and therefore the sheet 2 of alkaloids containing material that is cast on top of the conveyor belt 3.

(14) The cast sheet 2 of alkaloids containing material is produced out of a slurry 5 that is a viscous or pasty mixture of particles, essentially made of finely ground tobacco material, where the particles are brought into a viscous or pasty form by mixing it with a solvent. As an example, water can be used as a solvent. Of course, additional solids compounds, additional liquid, viscous or pasty compounds or both can be part of the slurry 5 as well.

(15) The slurry 5 is contained in a casting box 6. The casting box 6 is open on the top, so that slurry 5 can be replenished. Towards the roller 4, or to be more exact: towards the conveyor belt 3 that is placed on top of the roller 4 in the vicinity of casting box 6, the casting box 6 is open as well, so that the slurry 5 will come in area-measured contact with the upper surface of conveyor belt 3. At three 7a, 7b, 7c of the four sides of casting box 6, the sidewalls 7a, 7b, 7c of the casting box 6 form a narrow gap with the corresponding surface part of the conveyor belt 3. In FIG. 1, this is the case for the proximal sidewall 7a that is arranged at the frontal side when seen in the moving direction 8 of conveyor belt 3. Furthermore, it is the case for the sideward sidewalls 7b, 7c. These walls 7a, 7b, 7c form a thin gap between their lower ends and the conveyor belt 3.

(16) At the fourth side of the casting box 6, an aperture is formed between the cutting edge 13 of a casting blade 9 and the conveyor belt 3. The aperture is of a rectangular shape and determines the cross-sectional shape of the sheet 2 of alkaloids containing material. Also, the thickness of the sheet 2 of alkaloids containing material is determined by the height of the aperture that is formed by the casting blade 9 and the conveyor belt 3. This relates to the “initial” thickness of the sheet 2 of alkaloids containing material, since the thickness may change due to a drying process. Typically, a shrinkage of the sheet 2 of alkaloids containing material occurs, for example during drying.

(17) A size of the aperture formed by the cutting edge 13 of the casting blade 9 and the upper surface of the conveyor belt 3 has to remain constant to obtain a sheet 2 of alkaloids containing material with constant thickness.

(18) However, a constant height of the casting blade 9 does not guarantee such a homogeneous thickness of the cast sheet 2 of tobacco material. This is, because the roller 4 may show some flat areas. This can easily occur with time due to wear of the casting apparatus 1. On the contrary, some dirt that is present on the roller 4 (or on the lower side of the conveyor belt 3) may lead to a small bump, decreasing the thickness of the sheet 2 of alkaloids containing material.

(19) Furthermore, the conveyor belt 3 might show some protrusions or recesses after some time as well, in particular due to wear. Then, the fixed height of the casting blade 9 will mean that the size of the aperture will vary, and consequently, the thickness of the cast sheet 2 of alkaloids containing material will not be homogeneous. It has to be noted that small variations in thickness of the cast sheet 2 of tobacco material may already cause noticeable variations in the smoking experience for the end consumer, even if the variation is only in the order of some 20 μm to 30 μm. Such small variations, however, are not unlikely to occur.

(20) Therefore, in FIG. 2 a method for producing a cast sheet 2 of alkaloids containing material is proposed which will be further explained with reference to FIG. 2. For the sake of clarity, the slurry 5 and the cast sheet 2 of alkaloids containing material are not shown in FIG. 2 (neither in FIGS. 3 and 4).

(21) Seen in the moving direction 8 of the roller 4 and the conveyor belt 3, the casting box 6 and the casting blade 9 are arranged prior to the topmost point 12 of roller 4 and are arranged neighbouring each other. More exactly, the cutting edge 13 of casting blade 9 is arranged at an angle 14 of about 24° to 25° before the top most point 12 of roller 4—and therefore of the highest point of conveyor belt 3 as well (at least in the proximity of roller 4).

(22) As can be further seen, contact elements 11 are placed on the windward side of casting blade 9 and on the leeward side of casting box 6. The contact elements 11 are attached both to the casting box 6 and to the casting blade 9. The contact elements 11 are presently made of a plastic material that has a comparatively low friction in contact with the moving conveyor belt 3. In detail, even a slight lubrication effect can be realized by a suitable choice for the material of contact elements 11. The lower surface of the contact elements 11 is formed in a way that corresponds to the local curvature of the conveyor belt 3, the contact element 11 is in contact with. Therefore, the lower surface of the contact elements 11 is slightly concave (corresponding to the slightly convex shape of the conveyor belt 3, which again corresponds to the curvature of roller 4).

(23) In case the conveyor belt 3 has a locally smaller or larger thickness, or in case the roller 4 has a protrusion or a recess on its outer circumferential surface, the contacting element 11 will move up and down together with the current outer surface of the conveyor belt 3 thanks to contact elements 11 being in gliding contact with the surface of the conveyor belt 3. Therefore, casting blade 9 moves along with the contacting elements 11 with respect to height and therefore follows any inhomogeneities of the surface of conveyor belt 3. Therefore, a more homogeneous thickness of the casted sheet 2 of alkaloids containing material can be realized. Local deviations of the outer circumferential surface of conveyor belt 3 can thus be compensated in the vicinity of the casting arrangement.

(24) Presently, one contact element 11 is placed on both sides of the cast sheet 2 of alkaloids containing material. The contact elements 11 are still within the region of conveyor belt 3, so that they contact the surface of the conveyor belt.

(25) In FIG. 3, another possible embodiment of how to cast a sheet 2 of alkaloids containing material with a more homogeneous thickness is depicted. Essentially, the casting process is quite similar to the embodiment as shown in FIG. 2. However, in the present example, the contact elements 11 are arranged on the leeward side of the moving direction 8 of conveyor belt 3 and roller 4. The casting blade 9 is not directly attached to the contact elements 11. Instead, adjustment screws 15 are employed, so that the height of the casting blade 9 can be raised or lowered with respect to the position of the contact elements 11. Therefore, the height of the aperture and therefore the thickness of the cast sheet 2 of alkaloids containing material can be varied, in particular from one batch to another.

(26) In all embodiments, the contacting elements 11 and therefore the casting blade 9 moves up and down along with any variations of the outer circumferential surface of conveyor belt 3. Therefore, the casting apparatus 1 will allow the production of a cast sheet 2 of alkaloids containing material with a more homogeneous thickness.

(27) In FIG. 4, another modification of the casting apparatus 1 is shown.

(28) Here, instead of contact elements 11 that work purely mechanically, two position sensors 16 are used. The contacting tip 17 of the position sensors 16 will measure the current position of the outer circumferential surface of conveyor belt 3 that is in contact with the contacting tip 17. In particular, any variations from the nominal position are registered by the position sensors 16 and are sent via cables 18 to a controller 19. The controller 19 inputs the sensor data and generates a control signal that is sent to a stepper motor 20 via another cable 18. Using the stepper motor 20, the height of the casting blade 9 is raised a lowered appropriately, so that an aperture with a constant size can be realized (despite of any fluctuations of the height of the outer surface of conveyor belt 3). Thus, a cast sheet 2 of alkaloids containing material can be produced that shows a more homogeneous thickness.

(29) The controller 19 can be set up in a way to introduce a time delay Δt between the repositioning of the casting blade 9 by stepper motor 20 with respect to a signal received by position sensors 16. One has to realize, that a certain time will pass, before a certain area of the conveyor belt will move from a position neighbouring the contact tips 17 to a position neighbouring the cutting edge 13 of casting blade 9. The delay time to be chosen depends on the speed of the conveyor belt 3 υ and the distance d between the contact tips 17 and the cutting edge 13 of the casting blade 9. Preferably the delay time should be chosen to be Δt=d/υ.

(30) Using this embodiment, it is possible to account for any locally confined variations of the outer circumferential surface of conveyor belt 3. This way, a sheet 2 of alkaloids containing material with an even more homogenous thickness can be realized.

(31) It is to be noted that is even possible to interchange the arrangement of the casting blade 9 and the position sensors 16, so that the position sensors 16 are arranged behind the casting blade 9 with respect to the moving direction 8 of the conveyor belt 3. Then, the time delay Δt has to be chosen quite large, since the time delay is now based on the difference of the overall length of the conveyor belt 3 D (length that will be passed before a certain piece of the conveyor belt will show up again at a certain position) and the distance d between the contact tips 17 and the cutting edge 13 of the casting blade 9. Therefore, the delay time will be Δt=(D−d)/υ.

(32) It is to be noted that the embodiments shown are presently given for illustrative purposes and are not meant to be limiting the scope of the invention in any case.

(33) In particular, it is also possible to combine certain features of the certain embodiments given in a way that is obvious to a person skilled in the art.