Method and apparatus for winding a sheet of homogenized tobacco material into a bobbin

Abstract

The invention relates to a method for winding a sheet (13) of homogenized tobacco material into a bobbin (12), the method comprising: providing a sheet of homogenized tobacco material having a free end (11); connecting the free end to a center core; rotating the center core so as to wind the sheet of homogenized tobacco material around it forming the bobbin; and applying a force per unit length to the sheet of homogenized tobacco material during winding to pull the same having a magnitude comprised between about 42 N/m and about 93 N/m.

Claims

1. Method for winding a sheet of homogenized tobacco material into a bobbin, the method comprising: providing a sheet of homogenized tobacco material having a free end, including: forming a tobacco composition using particulate tobacco or a tobacco particulate blend, a humectant and an aqueous solvent to form the tobacco composition; and casting, extruding, rolling, or pressing the tobacco composition to form the sheet of homogenized material from the tobacco composition; connecting the free end to a center core; rotating the center core so as to wind the sheet of homogenized tobacco material around the center core to form the bobbin; applying a force per unit length to the sheet of homogenized tobacco material during winding to pull the same having a magnitude comprised between about 42 N/m and about 93 N/m; determining one or more parameters of an ambient where the sheet of homogenizing tobacco material is located; selecting a sub-range of force's magnitudes within the range of magnitudes of forces per unit length of between about 42 N/m and about 93 N/m; and during winding of the bobbin, varying the value of the force per unit length used to pull said sheet of homogenized tobacco material within said sub-range depending on the value of the one or more parameters of the ambient.

2. The method according to claim 1, wherein the force per unit length has a direction tangent to an outer surface of said bobbin.

3. The method according to claim 1, comprising one or more of the following: determining the composition of the sheet of homogenizing tobacco material; determining the grammage of the sheet of homogenizing tobacco material; determining the humidity of the sheet of homogenizing tobacco material; and it also comprises: varying the value of the force per unit length used to pull the sheet of homogenized tobacco material during winding depending on the value of one or more between the composition, the grammage, or the humidity of said sheet of homogenizing tobacco material.

4. The method according to claim 1, comprising: measuring a diameter of the bobbin while winding.

5. The method according to claim 4, including: measuring an electrical resistance between a surface of the bobbin and the center core; and detecting electrical resistance variations during winding so as to calculate the diameter of the bobbin.

6. The method according to claim 1, comprising: generating said force per unit length by rotating the center core by means of an electric motor.

7. The method according to claim 6, comprising: changing the power absorbed by the motor as a function of a diameter of the bobbin during winding of the bobbin.

8. The method according to claim 7, comprising: increasing the power absorbed by the motor while increasing the diameter of the bobbin.

9. The method according to claim 1, comprising: keeping an angular velocity of said center core substantially constant during winding of the bobbin.

Description

(1) Further advantages of the invention will become apparent from the detailed description thereof with no-limiting reference to the appended drawings:

(2) FIG. 1 is a schematic lateral view of a winding apparatus according to the invention for winding a bobbin;

(3) FIG. 2 is a further schematic view of the winding apparatus of FIG. 1, at the beginning of the winding process; and

(4) FIG. 3 is a lateral view of the winding apparatus of FIG. 1 or 2 without the homogenized tobacco sheet.

(5) With reference to the figures, a winding apparatus for winding a bobbin according to the present invention is represented and indicated with reference number 10.

(6) The apparatus 10 is adapted to wind a bobbin 12. For instance, the bobbin 12 can be a homogenized tobacco material bobbin. The bobbin 12 shown in the figures has a round, for example cylindrical, shape. However, the invention works fine with bobbins even when the bobbins do not have round shape.

(7) The apparatus 10 comprises a bobbin holder 14 or center core where the bobbin 12 is placed.

(8) The bobbin 12 is formed by a homogenized tobacco sheet 13. The apparatus 10 is adapted to wind the homogenized tobacco sheet 13 of the bobbin 12, as shown in FIG. 1.

(9) The apparatus 10 also comprises a motor 20 and a control unit 30, both schematically depicted in FIG. 1 as rectangles. The motor 20 is coupled to bobbin holder and is adapted to rotate the same along an axis 21 of the bobbin holder. For example, in case the bobbin holder 14 is a cylinder, axis 21 is the axis of the cylinder.

(10) The control unit 30 is connected to motor 20 and is adapted to control, among others, the power absorbed by the motor, the speed of the motor, and other variables.

(11) Further, apparatus 10, as shown in FIG. 3, includes a diameter sensor 40 adapted to measure the diameter of the bobbin 12 during winding. The diameter sensor 40 includes a rail 41 extending from the bobbin holder 14 along a radius of a cross section of the same, and preferably from its axis 21, for a given length, preferably longer than the maximum diameter reachable by a bobbin. In the rail 41, a roller 42 can slide, so as to translate along the rail. Further, roller 42 can also rotate along an axis 43, preferably parallel to the axis 21 of the bobbin holder 14. The roller 42 can shift along rail up and down along the arrow 44 depicted in FIG. 3 and rotate along its axis as depicted by arrow 45 also shown in FIG. 3.

(12) The winding of the homogenized tobacco sheet 13 to form bobbin 12 takes place as follows. First, a free end 11 of the homogenized tobacco sheet 13 is connected to the bobbin holder 14. The connection takes place in such a way that the free end 11 of the sheet 13 extends tangent to the bobbin holder 14. The bobbin holder 14 is then rotated by means of motor 20, while keeping the sheet 13 tangent to the bobbin that forms winding one layer on top of the other of the sheet 13.

(13) The control unit 30 controls motor 20 so that the angular velocity of bobbin holder 14 remains substantially constant. Further, the control unit 30 controls the power absorbed by motor 20 so that the pulling force 50 (depicted as an arrow in FIG. 1) per unit length with which the sheet is pulled at the junction between a free portion of the sheet and the bobbin where the layers of the sheet are wound is comprised between about 42 N/m and about 93 N/m.

(14) In order to determine the power to be absorbed by the motor, preferably the diameter of the bobbin is checked by means of sensor 40. The distance between roller 42 which rotates on the free surface of the bobbin, that is, on the last wound layer of the sheet 13, and the axis 21 varies with the increasing diameter size of the bobbin 12. An electrical resistance between the two points in the rail 42 where the roller 42 is and the center of the bobbin holder, that is, the position of axis 21, is determined during the winding, obtaining a value of the bobbin diameter.

(15) From the equation (1), the power is determined, power controller by control unit 30. Preferably, the control unit 30 controls the power absorbed by motor 20 so that the pulling force magnitude remains substantially constant during winding or that the pulling force magnitude remains within a sub-range of the range comprised between about 42 N/m and about 93 N/m.

(16) The optimal pulling force 50 is determined on the basis of characteristics of the sheet 13, for example its composition, grammage and humidity, and/or on the basis of parameters of the ambient where the sheet 13 is wound, for example on the basis of the humidity of air, its temperature and others.

(17) During winding, the pulling force magnitude can be changed, for example if the ambient condition changes. The control unit 30 consequently varies the controlling parameters of the motor 20.