CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims priority from Italian patent application no. 102020000026122 filed on November 3, 2020, the entire disclosure of which is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a cutting unit for a tubular body.

The cutting unit object of the present invention finds advantageous application in a manufacturing machine for straws, to which the following disclosure will explicitly refer without losing generality. Furthermore, the present invention refers to a manufacturing machine for straws comprising the cutting unit.

PRIOR ART

A known manufacturing machine for the production of straws envisages unwinding a band of material from a reel, applying a continuous thread of glue on one edge of the band, and then bending the band on itself so as to give the band a tubular shape in order to form a tubular body; subsequently, the tubular body is cut crosswise and cyclically to separate a series of straws from the tubular body.

Generally, both ends of a straw are flat, but for some applications (typically when a portion of a straw needs to be inserted into a beverage container by breaking through a cap that seals a dispensing opening) the straw needs to have a flat end (which is grasped by the user's lips) and a pointed end (to more effectively break through the cap that seals the dispensing opening).

Currently, the tubular body is always and only cut with straight cuts to separate from the tubular body a number of straws having both flat ends; subsequently, in another processing station, one end of each straw is subject to a further cut to give the end a pointed shape.

The patent application FR2488183A1 describes a device for the inclined cutting of a continuous tube in order to obtain a series of straws.

The patent application JPH10100097A describes a cutting device for straws which makes inclined cuts.

The patent application EP1815757A1 describes a cutting device for cutting crosswise two continuous tobacco rods and thus obtaining a series of cigarettes.

DESCRIPTION OF THE INVENTION

The object of the present invention is to provide a cutting unit for a tubular body which allows to obtain straws having a flat end and a pointed end in a simpler and more efficient way while maintaining a high production quality (namely, sharp edges, that is, free of burrs or jaggedness and precise, and without crushing the straw in the area of the cut).

According to the present invention, a cutting unit is provided for a tubular body, according to what is established in the annexed claims.

The claims describe preferred embodiments of the present invention forming an integral part of the present description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described with reference to the attached drawings, which illustrate some non-limiting embodiments thereof, wherein:

Figure 1 is a perspective view of a straw applied to a beverage package;

Figure 2 is a perspective view and with parts removed for clarity of a cutting unit for a tubular body produced according to the present invention;

Figure 3 is a perspective view and with parts removed for clarity of a counter-cutting device of the cutting unit of Figure 2;

Figure 4 is a schematic side view of a cutting drum of the cutting unit of Figure 2;

Figure 5 is a plan and schematic view of the cutting drum of Figure 4;

Figure 6 is a schematic and front view of part of the cutting unit of Figure 2;

Figure 7 is a schematic and plan view of a guide element for the tubular body of a variation of the counter-cutting device of Figure 3; and

Figures 8, 9 and 10 are sectional views of the guide element of Figure 7 according to the lines of section VIII-VIII, IX-IX and X-X, respectively.

PREFERRED EMBODIMENTS OF THE INVENTION

In Figure 1, number 1 denotes as a whole a straw which is applied to the back of a beverage package. The straw 1 has a flat end 2 (which is grasped by the user's lips) and a pointed end 3 (to more effectively break through a cap that seals a dispensing opening of the package).

In Figure 2, number 4 denotes as a whole a cutting unit to obtain the straws 1 of a given length starting from two continuous tubular bodies 5 parallel to one another and packaged by a double-line manufacturing machine (known and not illustrated) supporting the cutting unit 4; in use, the two tubular bodies 5 move along a rectilinear (and generally horizontal) moving direction D with continuous motion, namely, with a law of motion that provides for a constant movement speed (namely, without a cyclical alternation of motion steps and stopping steps). It should be noted that the tubular bodies 5 can be made of a plastic material, a paper material or a mixed material. Preferably, the tubular bodies 5 are made of paper (monolayer or multilayer).

The cutting unit 4 comprises a fixed frame 6, which is rigidly mounted on a frame (not illustrated) of the manufacturing machine.

The frame 6 of the cutting unit 1 supports a cutting head 7 comprising a cutting drum 8, which is mounted so as to rotate around a rotation axis 9 and is provided with (at least) two radial blades 10 (better illustrated in Figures 4 and 6), each of which, in use, cuts both tubular bodies 5 crosswise and in rapid succession.

The tubular bodies 5 are fed simultaneously and at the same speed by means of a counter-cutting device 11, which forms part of the cutting unit 4, is carried by the frame 6 and comprises a series of pairs of guide elements 12 (or also guide sleeves 12, better illustrated in Figure 3) of the tubular bodies 5. According to what is illustrated in Figure 3, each guide element 12 has a through and transverse slit 13 (that is, arranged crosswise to the moving direction D of the tubular bodies 5) which, in use, is crossed by a blade 10 of the cutting drum.

An actuation system 14 operates the guide elements 12 by imparting to the guide elements 12 a given law of cyclic motion synchronized with the rotation of the cutting drum 8; in particular, the actuation system 14 feeds the two guide elements 12 of each pair for a given distance together with the tubular bodies 5 so that each guide element 12 embraces the respective tubular body 5 and moves synchronously together with the tubular body 5 during the execution of the transverse cut (namely, during the passage of a blade 10). According to a preferred embodiment illustrated in Figure 3, each guide element 12 has a "U"-shaped section and the actuation system 14 comprises a carousel 15, which is rotatable around its own central rotation axis 16 and supports the guide elements 12 by means of the interposition of an articulated parallelogram (not illustrated) so as to keep the guide elements 12 always parallel to the moving direction D of the tubular bodies 5. According to an embodiment not illustrated, instead of the carousel 15 the actuation system 14 can comprise other means for moving the guide elements 12 commonly known and, hence, not described in the following.

According to what is illustrated in Figure 2, the cutting head 7 is provided with an electric motor 17 to rotate the cutting drum 8 around the central rotation axis 9; the actuation system 14 is provided with an electric motor 18 mechanically independent from the electric motor 17 and with a driving device of the electric motor 18 in order to synchronize the electric motor 18 to the electric motor 17 by using a "master-slave" type control logic wherein the electric motor 17 is the "master" and the electric motor 18 is the "slave".

According to a possible embodiment, each guide element 12 has a weakened portion to break in a controlled manner in the event of excessive mechanical stresses on the guide element 12 resulting from a loss of synchronism between the two electric motors 17 and 18 and to avoid further damage to the countercutting device 11. In this way, in the event of a loss of synchronism between the two electric motors 17 and 18, any possible breakage occurs in a controlled manner on the guide elements 12, which are inexpensive and can be replaced fairly quickly. According to an alternative embodiment, each guide element 12 is shaped so as to deflect the blade 10 and, hence, determine the controlled breakage of the blade 10 in case of loss of synchronism between the two electric motors 17 and 18 and to avoid damage to the counter-cutting device 11. In this way, in the event of a loss of synchronism between the two electric motors 17 and 18, any breakage occurs in a controlled manner on the blade 10, which is inexpensive and can be replaced fairly quickly.

According to what is illustrated in Figure 5, the rotation axis 9 of the cutting drum 8 is not parallel to the moving direction D of the tubular bodies 5, but forms an angle a (generally comprised between 8° and 15° depending on the length of the straws 1) relative to the moving direction D; furthermore, each blade 10 forms with the rotation axis 9 of the cutting drum 8 an angle complementary to the angle a. In this way, in use each blade 10 not only has a component of transverse motion (which is in any case prevalent) relative to the moving direction D but also has a component of motion parallel to the moving direction D to accompany, during the cut, the movement of the tubular bodies 5 along the moving direction D. According to a preferred embodiment, the cutting head 7 is mounted so as to rotate on the frame 6 to rotate around an adjustment axis and can be locked in any angular position around the adjustment axis to vary the width of the angle a formed between the rotation axis 9 of the cutting drum 8 and the moving direction D of the tubular bodies 5. Preferably, the cutting head 7 is provided with an electric motor to impart to the cutting head 7 movements around the adjustment axis. In order to modify the length of the straws 1 cut by the cutting unit 1 it is necessary to modify the width of the angle a formed between the rotation axis 9 of the cutting drum 8 and the moving direction D of the tubular bodies 5 to ensure that the line of interference between each blade 10 and the tubular bodies 5 moves, during the cut, at the same speed as the tubular bodies 5.

According to what is illustrated in Figures 4 and 6, a blade 10a and two corresponding guide elements 12a are configured to hold (at least during the cut but preferably always) the blade 10a perpendicular to the moving direction D of the tubular bodies 5 so as to form a right angle with the moving direction D of the tubular bodies 5; consequently, the blade 10a when performing the transversal cut of the tubular bodies 5 forms the flat ends 2 of the straws 1. Furthermore, a blade 10b and two corresponding guide elements 12b are configured to hold the blade 10b, at least during the cut, inclined relative to the moving direction D of the tubular bodies 5 so as to form an acute angle (preferably equal to 45°) with the moving direction D of the tubular bodies 5; consequently, the blade 10b, when performing the transversal cut of the tubular bodies 5, forms the pointed ends 3 of the straws 1.

The blade 10a always and only cooperates with the two guide elements 12a (which are shaped to cooperate with the blade 10a but not with the blade 10b), whereas the blade 10b always and only cooperates with the two guide elements 12b (which are shaped to cooperate with the blade 10b but not with the blade 10a).

According to a preferred embodiment illustrated in the attached figures, the carousel 15 supports two guide elements 12a which cooperate alternatively only with the blade 10a and two guide elements 12b which cooperate alternatively only with the blade 10b; according to other embodiments not illustrated, the carousel 15 could support only one guide element 12a and only one guide element 12b or it could support three or more guide elements 12a and three or more guide elements 12b.

According to a preferred embodiment, each guide element 12a is configured not to subject the blade 10a to any deformation and, hence, the blade 10a always has the same shape during the entire rotation of the cutting drum 8; namely, the blade 10a always has the same shape which, in use, is never modified during rotation of the cutting drum 8. In particular, the slit 13 of each guide element 12a is configured to never touch the blade 10a and has a flat shape which extends along the entire extension of the slit 13 on a single plane forming a right angle with the moving direction D of the tubular bodies 5.

According to a first embodiment illustrated in Figures 4 and 6, each guide element 12b is configured not to subject the blade 10b to any deformation and, hence, the blade 10b always has the same shape throughout rotation of the cutting drum 8; namely, the blade 10b always has the same shape which, in use, is never modified during rotation of the cutting drum 8. In particular, the slit 13 of each guide element 12b is configured to never touch the blade 10b and has a flat shape which extends along the entire extension of the slit 13 on a single plane forming an acute angle (preferably equal to 45°) with the moving direction D of the tubular bodies 5.

According to a different embodiment illustrated in Figures 7- 10, each guide element 12b is configured to subject the blade 10b to an elastic deformation immediately before the execution of the cut and to a following elastic counter-deformation immediately after the execution of the cut and, hence, the blade 10b does not always have the same shape during the entire rotation of the cutting drum 8. In particular, the blade 10b is normally arranged to form a right angle with the moving direction D of the tubular bodies 5 outside the guide elements 12b (namely, to have the same arrangement as the blade 10a) and is deformed to form an angle acute (preferably equal to 45°) with the moving direction D of the tubular bodies 5 only within the guide elements 12b. Consequently, the blade 10b forms a right angle with the moving direction D of the tubular bodies 5 before and after the execution of the cut and forms an acute angle (preferably equal to 45°) with the moving direction D of the tubular bodies 5 only during cutting.

In particular, the slit 13 of each guide element 12b is configured to impart elastic deformations to the blade 10b and, hence, the slit 13 of each guide element 12b has an input portion 19 and an output portion 20 which are coplanar to one another and both lie on a first plane forming a right angle with the moving direction D of the tubular bodies 5 and a central (operative) portion 21 which is arranged between the input portion 19 and the output portion 20 and lies on a second plane forming an acute angle (preferably equal to 45°) with the moving direction D of the tubular bodies 5. The central portion 21 is connected to the input portion 19 and to the output portion 20 by means of respective connecting portions 22: the portions 19, 20 and 22 have a constant inclination along their entire extension, whereas the two connecting portions 22 have, along their extension, a progressively variable inclination; consequently, the blade 10b maintains the same inclination when it is in the portions 19, 20 and 21 whereas its inclination progressively varies when the same is in the two connecting portions 22.

In use, a blade 10b is perpendicular to the moving direction D of the tubular bodies 5 before entering the slit 13 of a guide element 12b, upon entering the input portion 19 of the slit 13, it remains perpendicular to the moving direction D, therefore entering the connection portion 22 it tilts progressively until reaching a desired angle (preferably equal to 45°) with the moving direction D upon entering the central (operative) portion 21. When the blade 10b is in the central (operative) portion 21, it carries out the transversal cut of the tubular bodies 5 and then, after completing the transversal cut of the tubular bodies 5, it comes out of the slit 13 passing first through the connection portion 22, along which the blade 10b is bent again to progressively return to a position perpendicular to the moving direction D.

According to a preferred embodiment illustrated in Figure 2, the cutting unit 4 comprises two sharpening devices 23, which are arranged beside the cutting drum 8 and are designed to sharpen the corresponding blades 10; according to a preferred embodiment, a sharpening device 23 is designed to sharpen always and only the blade 10a while the other sharpening device 23 is designed to sharpen always and only the blade 10b. According to a different embodiment, not illustrated, a single sharpening device 23 is provided for both blades 10.

According to a preferred embodiment, each blade 10 is mounted so as to be radially movable on the cutting drum 8 so as to cyclically radially come out of the cutting drum 8 in order to compensate for the wear of the blade 10; namely, an actuator is provided which cyclically (for example, every 1000 cutting cycles) makes each blade 10 to radially come out of the cutting drum 8 (for example, by a predetermined quantity of the order of tenths or hundredths of a millimetre) to compensate for the wear of the blade 10 (following the sharpening operations performed by the sharpening devices 23). In this regard, it is important to note that in the embodiment illustrated in Figures 4 and 6 (in which the blade 10b is permanently bent so as to form an acute angle with the moving direction D of the tubular bodies 5), only the portion of the blade 10b which comes out of the cutting drum 8 could be bent (relative to the radial orientation) whereas the portion of the blade 10b which is inside the cutting drum 8 could be radially arranged.

In the embodiments illustrated in the attached figures, the cutting unit 4 is shaped so as to perform the transversal cut of two tubular bodies 5 side by side and parallel to one another (packaged by a double-line manufacturing machine); according to a different embodiment not illustrated, the cutting unit 4 is shaped so as to perform the transversal cut of a single tubular body 5 (packaged by a single-line manufacturing machine).

The embodiments described here can be combined with each other without departing from the scope of the present invention.

The present invention also relates to a manufacturing machine (not illustrated) for straws. Said manufacturing machine comprises: a unit for forming a tubular body 5 which is configured to receive a wrapping material band and to bend it in order to give the band a tubular shape so as to form the tubular body 5, which is moved with a continuous motion along a moving direction D; and a cutting unit 4 According to any of the above-described embodiments, which cutting unit 4 is arranged downstream of the forming unit so as to cut the tubular body 5 and obtain a plurality of straws.

In detail, the forming unit comprises: a forming beam having a longitudinal development along the moving direction D and at which the band is bent to give it a tubular shape; at least one gluing device arranged at or upstream of the forming beam to lay a strip of glue at one edge of the belt.

The wrapping material band fed into the forming unit of the tubular body 5 can be made of a paper material and/or of a plastic material. Furthermore, this wrapping material band can be formed by a single layer or formed by multiple layers of wrapping materials.

According to a further embodiment, the manufacturing machine for straws can comprise two or more units for forming a tubular body, for example, arranged side by side, so as to form several tubular bodies 5 at the same time.

The embodiments described herein can be combined with each other without departing from the scope of the present invention.

The cutting unit 1 described above has numerous advantages.

Firstly, the cutting unit 1 described above allows to obtain straws 1 having a flat end 2 and a pointed end 3 in a simple and efficient way while maintaining a high production quality (namely, sharp edges, that is, without burrs or jaggedness and precise, and without crushing the straw 1 at the cut). Furthermore, the cutting unit 1 described above is simple, inexpensive and compact to manufacture.