METHOD FOR UNWINDING A BOBBIN OF A COILED SHEET AND UNWINDING APPARATUS FOR UNWINDING A BOBBIN

Abstract

The present invention relates to a method for unwinding a bobbin of a coiled sheet, the method comprising: providing a bobbin of a coiled sheet, the bobbin comprising a free portion of the sheet unwound from the bobbin; arranging a blade between the free portion of the sheet and the remaining of the sheet coiled in the bobbin in such a way that the blade is in contact to the sheet coiled in the bobbin; and vibrating the blade while unwinding the sheet from the bobbin. The present invention also relates to an unwinding apparatus for unwinding a bobbin.

Claims

1. Method for unwinding a bobbin of a coiled sheet, the method comprising: providing a bobbin of a coiled sheet, the bobbin comprising a free portion of the sheet unwound from the bobbin; arranging a blade between the free portion of the sheet and the remaining of the sheet coiled in the bobbin in such a way that the blade is in contact to the sheet coiled in the bobbin; and vibrating the blade while unwinding the sheet from the bobbin.

2. Method according to claim 1, comprising: applying pressure on the bobbin in a contact region between the blade and the sheet coiled in the bobbin.

3. Method according to claim 1, comprising: pulling the free portion of the sheet while unwinding the bobbin.

4. Method according to claim 1, wherein the step of applying pressure comprises: shifting the blade towards the bobbin when a dimension of the bobbin is reduced due to the unwinding.

5. Method according to claim 1, wherein the step of vibrating the blade comprises: vibrating the blade at a frequency comprised between about 10 kilohertz and about 100 kilohertz.

6. Method according to claim 1, wherein the step of arranging the blade comprises: providing a blade having an edge portion; and arranging the blade so that the edge portion of the blade is substantially tangential to the sheet coiled in the bobbin at a contact region between the edge portion and the sheet coiled in the bobbin.

7. An unwinding apparatus for unwinding a bobbin, the apparatus comprising: a bobbin holder where a bobbin of a coiled sheet is placed; a blade arranged in front of the bobbin holder and adapted to be in contact to the sheet coiled in the bobbin; and a vibration generator connected to the blade and adapted to put the blade into vibrations while the sheet is unwinding from the bobbin.

8. The unwinding apparatus according to claim 7, wherein the vibration generator is an ultrasonic generator adapted to generate vibrations of the blade between about 10 kilohertz and about 100 kilohertz.

9. The unwinding apparatus according to claim 7, wherein the blade comprises an edge portion adapted to contact the sheet coiled in the bobbin, the edge portion comprising a first and a second surfaces forming an angle therebetween of about 125.

10. The unwinding apparatus according to claim 7, wherein the blade comprises a body portion adapted to face a free portion of the sheet unwound from the bobbin, the body portion comprising a first and a second surfaces forming an angle therebetween of about 21.

11. The unwinding apparatus according to claim 7, comprising a position adjustment system, adapted to change the position of the blade with respect to the bobbin holder depending on a dimension of the bobbin present in the holder.

12. The unwinding apparatus according to claim 11, comprising a control unit connected to the position adjustment system and adapted to command the position adjustment system to move the blade towards the bobbin as the dimension of the bobbin reduces due to unwinding.

13. The unwinding apparatus according to claim 11, wherein the position adjustment system includes a rail wherein a support of the blade can slide towards and moving away from the bobbin holder, and a weight to pull the support towards the bobbin holder by gravity.

14. The unwinding apparatus according to claim 13, wherein the vibration generator, connected to the blade, is coupled to the rail so as to slide therein.

15. The unwinding apparatus according to claim 7, wherein the blade is made of polytetrafluoroethylene or comprises a polytetrafluoroethylene coating.

16. The unwinding apparatus according to claim 7, comprising an arm connecting the vibration generator and the blade, the arm having a U-shaped form.

17. The unwinding apparatus according to claim 7, wherein the blade is arranged to be in contact to the sheet coiled in the bobbin substantially tangential to the sheet coiled in the bobbin at a contact region between the blade and the sheet coiled in the bobbin.

Description

[0037] Further advantages of the invention will become apparent from the detailed description thereof with no-limiting reference to the appended drawings:

[0038] FIG. 1 is a schematic perspective view of an unwinding apparatus according to the invention for unwinding a bobbin;

[0039] FIG. 2 is a further schematic perspective view of the unwinding apparatus of FIG. 1, taken from a different view point;

[0040] FIG. 3 is a lateral view of the unwinding apparatus of FIG. 2;

[0041] FIG. 4 is a schematic view of part of FIG. 3;

[0042] FIG. 5 is an enlarged lateral view of a portion of the unwinding apparatus of FIG. 3;

[0043] FIG. 6 is a plan view of the portion of the unwinding apparatus of FIG. 5; and

[0044] FIG. 7 is a front view (taken from the right of FIG. 5) of the portion of the unwinding apparatus of FIG. 5.

[0045] With reference to the figures, an unwinding apparatus for unwinding a bobbin according to the present invention is represented and indicated with reference number 10.

[0046] The apparatus 10 is adapted to unwind a bobbin 12.

[0047] For instance, the bobbin 12 can be a homogenized tobacco material bobbin. However, the invention can be applied to all industries where manufacturing processes include the unwinding of bobbins having sticky and fragile sheets, for instance, paper industry or industry using polymer sheets coiled in bobbins.

[0048] 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.

[0049] The apparatus 10 comprises a bobbin holder 14 where the bobbin 12 is placed.

[0050] The bobbin 12 is formed by a coiled sheet 13. The apparatus 10 is adapted to unwind the coiled sheet 13 of the bobbin 12, as shown in FIG. 1.

[0051] The apparatus 10 also comprises a blade 20 and a vibration generator 30.

[0052] The blade 20 is arranged in front of the bobbin holder 14 and is adapted to be in contact to the sheet 13 coiled in the bobbin 12. The blade 20 is preferably made of polytetrafluoroethylene (for instance Teflon) or is made of metal material and comprises a polytetrafluoroethylene coating. In this way, the sheet 13 (in particular, the homogenized tobacco material sheet) is protected both from friction which could lead to tearing and from heat which could damage or modify a component of the sheet (in particular, the homogenized tobacco material sheet).

[0053] The blade 20 is arranged to be in contact to the sheet 13 coiled in the bobbin 12 substantially tangential to the sheet 13 coiled in the bobbin 12 at a contact region 100 between the blade 20 and the sheet 13 coiled in the bobbin 12 (see FIGS. 1 and 3). In a non-limiting preferred embodiment, the contact region is substantially rectangular and it has a dimension of about 4 millimeters by about 120 millimeters. Due to its limited thickness, this contact area can be considered as a line.

[0054] According to the non-limiting shown embodiment, the blade 20 includes a body portion 24 terminating at one end portion 22 with a sharp edge. The blade 20 is substantially rectangular when seen in a plan view, as shown in FIG. 7. For instance, its dimensions are of about 150 millimetres in width, about 130 millimetres in length and about 4 millimetres in thickness on average.

[0055] Preferably, as better visible in FIG. 5, the blade thickness is not constant but is biased with a predetermined slope (for instance, a slope of about 2) from a first end portion 26 connected to the vibration generator 30 to the end portion 22 (second end portion 22) in contact with the bobbin 12. Furthermore, on the second end portion 22 in contact with the bobbin 12, the slope increases (for instance to about 12) so that the second end portion 22 is sharp defining the blade edge. For instance the second end portion 22 has a thickness of about 3 millimetres1 millimetres.

[0056] More in particular, the second end portion 22 is adapted to contact the sheet 13 coiled in the bobbin 12. The second end portion 22 is defined by opposite, substantially flat first and second surfaces 221, 222. The first and second surfaces 221, 222 form an angle therebetween of about 125.

[0057] The body portion 24 is adapted to face a free portion 133 of the sheet 13 unwound from the bobbin 12. The body portion 24 is defined by opposite, substantially flat first and second surfaces 241, 242. The first and second surfaces 241, 242 form an angle therebetween of about 21. The first surface 221 of the second end portion 22 and the first surface 241 of the body portion 24 are arranged on the same side 121 of the blade 20. This first side 121 is that opposite with respect to the bobbin holder 14 (see FIGS. 3-5). The first surface 221 of the second end portion 22 and the first surface 241 of the body portion 24 are substantially coplanar (see FIG. 5). In other words, the first side 121 defines a blade plane.

[0058] The second surface 222 of the second end portion 22 and the second surface 242 of the body portion 24 are arranged on the same second side 122 of the blade 20. This second side 122 is that facing the bobbin holder 14 (see FIGS. 3-5).

[0059] The apparatus 10 comprises a position adjustment system 40, shown in FIGS. 2 and 3. The position adjustment system 40 is adapted to change the position of the blade 20 with respect to the bobbin holder 14 depending on a dimension of the bobbin 12 present in the holder 14.

[0060] The apparatus 10 comprises a control unit 50 connected to the position adjustment system 40 and adapted to command the position adjustment system 40 to move the blade 20 towards the bobbin 12 as the dimension of the bobbin 12 reduces due to unwinding.

[0061] The position adjustment system 40 includes a rail 42 wherein a support 44 of the blade 20 can slide towards and moving away from the bobbin holder 14. Preferably, the support 44 slides on a pair of parallel rails 42 (see FIG. 3).

[0062] The position adjustment system 40 further includes a weight (not shown) to pull the support 44 towards the bobbin holder 14 by gravity.

[0063] Indeed, the rails 42 are not horizontal but are oriented towards the bobbin holder 14 with a predetermined slope angle downwards. In other words, the rails go downwards toward a center 1100 of the bobbin 12 and the support 44 slides downwards along the rails due to gravity. The above-mentioned weight is attached to the support 44 of the position adjustment system 40 to pull it toward the bobbin 12.

[0064] In this way, the position adjustment system 40 also defines a predetermined slope angle of the blade 20 with respect to a vertical direction. In other words, with reference to FIGS. 3 and 4, the blade 20 is not vertically oriented (that is, oriented as a vertical plane 1000 passing through the center 1100 of the bobbin holder 14 and therefore of the bobbin 12) but has a predetermined slope angle with respect to the vertical direction.

[0065] Preferably, the blade 20 is substantially tangentially oriented with respect to the bobbin 12 in the area of contact between the blade 20 and the bobbin 12. In other words, with reference to FIGS. 3 and 4, the blade 20 is substantially oriented as a plane 1200 tangent to the bobbin 12 and passing through a contact line between the sharp edge of the blade 20 and the bobbin 12.

[0066] More precisely, the blade 20 has a substantially planar configuration and the first side 121 defines the blade plane, as detailed above. The blade plane passes through the sharp edge of the blade 20 and is extended along a longitudinal extension of the blade 20. The first side 121 of the blade 20 is arranged substantially along a tangential plane to the bobbin 12 on the line of intersection between the edge of the blade 20 and the bobbin 12 itself. It is considered that the first side 121 of the blade 20 and the bobbin 12 are substantially tangential when the angle formed by the first side 121 and the tangential plane 1200 forms an angle of 0+/10 (see FIG. 4).

[0067] The position adjustment system 40 can use other systems (not shown). For instance, a proximity sensor capturing the distance from to the bobbin 12 can be provided. In this case, the proximity sensor is coupled with the support 44 which is suitably motorized.

[0068] The vibration generator 30 is connected to the blade 20 and adapted to put the blade 20 into vibrations while the sheet 13 is unwinding from the bobbin 12.

[0069] The vibration generator 30 is preferably an ultrasonic generator adapted to generate vibrations of the blade between about 30 kilohertz and about 35 kilohertz.

[0070] The vibration generator 30 comprises a motor 31 generating the vibrations.

[0071] The vibration generator 30 is connected to the blade 20 and is coupled to the rail 42 so as to slide therein. In particular, the vibration generator 30 is coupled to the support 44.

[0072] The apparatus 10 comprises an arm 32 connecting the vibration generator 30 and the blade 20. The arm 32 is U-shaped (see FIG. 6) to pass aside from the sheet 13 being unwound by the blade 20.

[0073] The vibration generator 30 generates specific vibrations on the arm 32. Indeed, the arm 32 is strongly attached to the blade 20 so that the blade 20 vibrates substantially with the same frequency and amplitude that the arm 32 of the vibration generator 30. According to a preferred embodiment, the arm 32 vibrates at ultrasonic speed, meaning it vibrates between about 30 kilohertz and about 35 kilohertz.

[0074] In particular, an end portion 132 of the arm 32 is connected to the side 122 of the blade 20 (see FIG. 6). Preferably, the end portion 132 is connected to the blade 20 at or near the edge portion 26 of the blade 20 itself (see FIG. 7). More preferably, the end portion 132 is connected to the blade 20 at a lateral portion of the side 122 (see FIGS. 6 and 7).

[0075] In the non-limiting example shown in the figures, the position adjustment system 40 adjusts the position of the blade 20 by adjusting the position of the vibration generator 30 to which the blade 20 is connected.

[0076] In this way, the position adjustment system 40 is not in contact with the vibrating arm 32 connected to the vibration generator 30. Therefore the position adjustment system 40 does not interfere with the vibrations generated by the vibration generator 30.

[0077] The operation of the unwinding apparatus 10 for unwinding the bobbin 12 is as follows.

[0078] The bobbin 12 of the coiled sheet 13 is provided and comprises the free portion 133 of the sheet 13 unwound from the bobbin 12.

[0079] The blade 20 is arranged between the free portion 133 of the sheet 13 and the remaining of the sheet 13 coiled in the bobbin 12 in such a way that the blade 20 is in contact to the sheet 13 coiled in the bobbin 12.

[0080] The blade 20 is vibrated while unwinding the sheet 13 from the bobbin 12.

[0081] Pressure is applied by the blade on the bobbin 12 in the contact region 100 between the blade 20 and the sheet 13 coiled in the bobbin 12.

[0082] The free portion 133 of the sheet 13 is pulled while unwinding the bobbin 12.

[0083] The above-mentioned pressure is applied on the bobbin 12 by shifting the blade 20 towards the bobbin 12 when a dimension of the bobbin 12 is reduced due to the unwinding.

[0084] The blade 20 is vibrated at a frequency comprised between about 30 kilohertz and about 35 kilohertz.

[0085] The blade 20 is preferably arranged so that the second end portion 22 of the blade 20 is substantially tangential to the sheet 13 coiled in the bobbin 12 at the contact region 100 between the edge portion 20 and the sheet 13 coiled in the bobbin 12. In particular, the blade 20 is arranged on the bobbin 12 so that the second end portion 22 of the blade 20 is toward the bobbin 12 and somewhat tangential to the bobbin 12. The flat side 121 of the blade 20 is toward the sheet 13 that is being unwound. Such disposition allows limiting the contact surface between the blade 20 and the bobbin 12 which generates friction and heat.

[0086] Once in position, the blade 20 (which is vibrating due to the vibration generator 30) applies vibrations at the very specific location where the sheet 13 is being unwound from the bobbin 12. The vibrations of the blade 20 are quite tangential to the bobbin 12 at an unwinding area. Further, the vibrations include a back and forth motion of the blade towards the bobbin.

[0087] The vibrating blade 20 transfers to the sheet 13, being unwound from the bobbin 12 but still substantially stuck to it, a controlled amount of force related to the frequency and amplitude of the vibrations.

[0088] This amount of force is applied to a limited portion of the sheet 13 due to the specific shape of the tool, that is, of the blade 20.

[0089] While the bobbin 12 is unwound, a pulling strength is simultaneously applied to sheet 13.

[0090] The blade 20 is moved toward the center 1100 of the bobbin 12 following the unwinding of the bobbin 12 and the shape of the bobbin 12, due to the position adjustment system 40.

[0091] The position adjustment system 40 includes control means arranged to automatically move the blade 20 as the bobbin 12 is unwound in a direction towards the rotation axis of the bobbin 12, at a speed equal to a speed of reduction of diameter of the bobbin 12.

[0092] The position adjustment system 40 comprises a weight to create by gravity an effort of contact between the blade 20 and the bobbin 12.

[0093] The blade 20 is coupled to the ultrasonic generator 30 during unwinding a coiled or rolled sheet 13, in order to prevent adhesion or facilitate detachment between the uncoiled/unrolled sheet 13 and the coil/roll 12.

[0094] In other words, the unwinding apparatus 10 is arranged to uncoil/unroll an elongated sheet 13 coiled or rolled to form a bobbin 13. The unwinding apparatus 10 comprises the blade 20 located between the bobbin 12 and a free portion 133 of the unwound elongated sheet 13. The blade 20 is coupled to an ultrasonic generator 30 arranged to vibrate the blade 20 contacting the free portion 133 of the unwound elongated sheet 13.

[0095] By using the apparatus 10 of the invention, the occurrences of breakings of the sheet 13 decrease and the yield of the sheet material advantageously increases.

[0096] Moreover, the apparatus 10 of the invention limits the heat transferred to the sheet. Therefore, in the case of tobacco cast leaves bobbins 12, the tobacco cast leaves are not damaged.

[0097] Furthermore, the apparatus 10 of the invention allows increasing the unwinding speed of the bobbins 12. The Applicant tested the apparatus 10 of the invention on tobacco cast leaves bobbins 12 and found that the unwinding speed can be substantially doubled with respect to the prior art apparatus, for instance from about 100 meters per minute to about 200 meters per minute.