MACHINE AND METHOD FOR MAKING STRAWS

Technical field

This invention relates to a machine and a method for making drinking straws.

Background art

In the prior art, drinking straws are typically made from a continuous tubular element, obtained, for example, by extrusion of PLA and then cut into segments defining the straws which are then sent on for further processing. In particular, the machine that does this comprises a longitudinal feed line followed by the continuous tubular element and by the straws after cutting, until reaching a transfer unit which changes the feed direction of the straws from longitudinal to transverse.

A machine of this type is known, for example, from document W02021/043790 and is provided with a pneumatic unit which expels the individual straws sideways towards a transverse conveyor.

The machine described above has the disadvantage of requiring a generator for producing blasts of compressed air which, at high production speeds, can be very complicated and subject to faults or frequent maintenance requirements. Moreover, the system is based on blasts of compressed air which are unable to ensure a uniform pushing action on the straws, with the risk of causing unwanted rotation of the straws and creating problems for the conveyor downstream.

Aim of the invention

In this context, the basic technical purpose of this invention is to provide a machine and a method for making straws to overcome the above mentioned disadvantages of the prior art. In particular, the aim of this invention is to provide a machine and a method for making straws, characterized by high reliability.

Another aim of the invention is to provide a machine and a method for making straws and to allow the orientation of the straws to be controlled in an optimum manner during the change in their feed direction.

Brief description of the drawings

The technical purpose indicated and the aims specified are substantially achieved by a machine and a method for making straws, comprising the technical features described in one or more of the appended claims 1 -16. The invention is described below with reference to the accompanying drawings, which illustrate a non-limiting embodiment of it, in which:

- Figure 1 is a schematic view of a machine for making straws according to the invention;

- Figure 2 is a perspective view of a transfer unit forming part of the machine of Figure 1 ;

- Figure 2A is a view of the transfer unit of Figure 2 with some parts omitted to better illustrate others;

- Figure 3 is a schematic transverse cross section of the transfer unit of Figure 2 during a step in its operation;

- Figure 4 is a scaled-up view of a detail from Figure 3;

- Figure 5 is a cross section of the transfer unit of Figure 2;

- Figure 6 is a perspective view of a components of the transfer unit of Figure 2;

- Figure 7 is another view of the transfer unit of Figure 2 with some parts omitted to better illustrate others;

- Figure 8 is a perspective view of a components of the transfer unit used in the machine of Figure 1 in a variant embodiment;

- Figures 9A and 9B show two views of a detail of the machine according to the invention, in a first variant embodiment and in two different operating positions; - Figures 10A and 10B show two views of a detail of the machine according to the invention, in a second variant embodiment and in two different operating positions.

Detailed description of preferred embodiments of the invention

In the accompanying drawings, the numeral 1 denotes in its entirety a machine for making straws in accordance with this invention.

The machine essentially comprises a forming unit 2 for forming a continuous tubular element T, a cutting unit 3 for cutting the continuous tubular element T into tubular segments 100 of predetermined length and, downstream of the cutting unit 3, a transfer unit 4 for the tubular elements 100, configured for transferring the segments 100 from a longitudinal feed direction to a transverse (perpendicular) feed direction.

The forming unit 2 is of known type and can make a continuous tubular element T from any material and with any structure. For example, the continuous tubular element T can be made by extrusion of plastic material or from paper material, in the latter case by longitudinally wrapping a single paper web, whether single-layer or multilayer, or by helically wrapping two or more paper webs. It is understood that the structure and material of the continuous tubular element T do not limit this invention. Figure 1 shows a solution where the continuous tubular element T is obtained by longitudinally wrapping a continuous web 200 unwound from a roll 300 and made to advance along a feed direction A.

The cutting unit 3 is also made according to known solutions, in particular using one or more rotary blades operating on the continuous tubular element T while it is being advanced longitudinally. The cutting unit 3 and the transfer unit 4 are distinct units.

Preferably, the segments 100 leaving the cutting unit 3 and constituting the straws have a length of between 8 and 40 cm, more preferably between 12 and 30 cm.

With reference to the transfer unit 4, a first embodiment of it is shown in Figures 2 to 7, where Figures 2a and 7 illustrate it with some parts omitted so as to better illustrate inner parts of it.

Looking in more detail, the transfer unit 4 comprises a support beam 5 is provided with a longitudinal groove 6 whose transverse cross section is preferably arcuate in shape and which is intended to feed the segments 100 in succession after they have been cut. In a possible embodiment not illustrated, one or more accelerator rollers may be located between the cutting unit 3 and the transfer unit 4 to accelerate the segments 100 so as to space them apart from each other.

Disposed above the support beam 5 is a mounting shaft 7 which is rotatable about an axis of rotation X parallel to the longitudinal groove 6 and on which a plurality of pushing elements 8, axially spaced along the axis X, are mounted. In the embodiment illustrated, there are four pushing elements 8 but, depending on requirements, there may be a different number of them, greater than or equal to one.

The mounting shaft 7 is rotated about the axis X by means of a rotary actuator M, preferably a servomotor, and this simultaneously sets the pushing elements 8 in rotation. The contact portions 8a of the pushing elements 8 are disposed in phase with each other in such a way that corresponding contact portions 8a of the pushing elements 8 simultaneously impact against different portions of the same segment 100.

Each pushing element 8 has a contact portion 8a designed to impact against a segment 100 to expel the segment transversely from the groove 6 and to deflect the segment 100 from the longitudinal feed direction defined by the groove 6 to a transverse feed direction, for example, towards a further conveyor or towards a container (not illustrated).

In the embodiment of Figure 2, each pushing element 8 has two contact portions 8a on opposite sides of the axis of rotation X, although the number of contact portions 8a may be different, in particular, a number greater than or equal to one. Figure 6 is a detail view showing one of the pushing elements 8 used in the embodiment of Figure 2. This pushing element 8 comprises a central portion 9 and a pair of radial arms 10 extending radially away from the central portion 9 in diametrically opposite directions and each defining a respective contact portion 8a.

The central portion 9 is provided with a radial recess 9a configured for laterally mounting the pushing element 8 on the mounting shaft 7, in particular, by transversely inserting the shaft 7 into the recess 9a. Further, the mounting shaft 7 is provided with a succession of receiving flanges 7a defining respective radial expansions of the mounting shaft 7 and each intended for frontally mounting the central portion 9 of a corresponding pushing element 8, for example reversibly, using threaded means.

More generally speaking, each pushing element 8 has a plurality of radial arms 10 angularly distributed around the central portion 9, in accordance with embodiments not illustrated.

In the embodiment illustrated, the axis of rotation X is disposed above the longitudinal groove 6, preferably in a substantially vertical position above the longitudinal groove 6.

Further, each contact portion 8a is flat and is configured and/or oriented in such a way as to be positioned substantially perpendicularly to the (horizontal) top surface of the support beam 5 at the instant of impact with a respective segment and/or in such a way that its movement is parallel with the top surface of the support beam 5 at the instant of impact with a respective segment 100.

In a variant embodiment not illustrated, the contact portion 8a is configured and/or oriented in such a way as to be inclined upwards at the instant of impact with a respective segment and/or in such a way that its movement has an upwardly directed component at the instant of impact with a respective segment 100, so as to facilitate expulsion of the segment 100 from the groove 6. In the specific embodiment illustrated in the accompanying drawings, each contact portion 8a lies in a plane passing through the axis of rotation X which, in the view of Figure 3, corresponding to the instant of impact against a segment 100, is oriented vertically.

In variant embodiments not illustrated, the axis of rotation X may be disposed below the level of the groove 6, preferably vertically below it, and the contact portions 8a intersect the upper plane of the support beam 5 in proximity to the instant of impact against the segment 100 and then return below it.

Preferably, the transfer unit 4 also comprises at least one upper guide element 1 1 defining, in conjunction with the support beam 5, a preferably horizontal channel 12, with a substantially constant thickness, for guiding the segments 100 transversely away from the longitudinal groove 6.

In the specific embodiment, the transfer unit 4 comprises a plurality of upper guide elements 1 1 in the form of brackets or plates, whose underside surfaces are parallel to the support beam 5 to define an upper guide for the segments 100. The upper guide elements 1 1 are spaced apart from each other along the groove 6 and are alternated with the pushing elements 8. Preferably, the transfer unit 4 also comprises one or more stop aprons 13 facing the support beam 5, more specifically the channel 12, and configured for receiving and stopping the segments 100 expelled transversely by the pushing elements 8 and also for axially stopping the segments 100 by friction. Preferably, the stop apron is made from flexible metallic mesh and hangs by a top portion of it so it is stretched under its own weight.

In the embodiment illustrated and as shown in Figure 2, there is a plurality of stop aprons 13 which are juxtaposed and spaced from each other. In a different embodiment, not illustrated, there is only one stop apron 13 which faces all the pushing elements 8.

Below the support beam 5 there is a chute 14 for guiding downwardly the segments 100 expelled laterally by the pushing elements 8. A variant embodiment shown in Figure 7 comprises, in addition or alternatively to the stop aprons 13, deformable braking elements 15 adapted to at least partly dampen/absorb the longitudinal kinetic energy of the segments 100. For example, the deformable braking elements 15 comprise brushes, a metallic or plastic or rubber mesh or elastic metal parts.

The deformable braking elements 15 are intended to be intercepted by the segments 100 after the segments have been transversely deflected by the pushing elements 8. Looking in more detail, the deformable braking elements 15 are alternated with the pushing elements 8 and extend downwardly into the channel 12 to partly obstruct the channel 12 so as to axially brake the segments 100. The deformable braking elements 15 are disposed at laterally offset positions, outwards, relative to the groove 6.

In the specific embodiment illustrated in Figures 1 -7, installed between two adjacent pushing elements 8, there is a mounting block 16, which is fixed to the support beam 5 or to another fixed structure and on which a stop apron 13, a deformable braking element 15 and two upper guide elements are mounted at the axial ends of the mounting block 16. The deformable braking element 15 is disposed at an intermediate position between the groove 6 and the stop apron 13.

According to an aspect of the invention, not illustrated, the contact portion 8a is made from elastically compliant or resilient material (while the rest of the pushing element is made from a rigid material, in particular, metal or light alloy). The elastically compliant or resilient material is preferably an elastomeric material or a brush portion. More preferably, the contact portion 8a is made in the form of a replaceable insert, applied, for example, using one or more threaded elements.

According to another aspect of the invention, the transfer unit 4 also comprises speed variation means to cause the pushing elements 8 to rotate at a slower speed in a controlled manner in proximity to the instant of impact between the contact portion 8a and a segment 100. In an embodiment, the speed variation means comprise an electronic control acting on the rotary actuator M. In a different embodiment, the speed variation means comprise a cam transmission (not illustrated), interposed between the rotary actuator M and the pushing elements 8, in particular, between the rotary actuator M and the mounting shaft 7.

Figure 8 shows a variant embodiment in which there is a single pushing element 8 (provided with two contact portions 8a but there might be any number of these, as described above). This pushing element 8 has a contact portion 8a that extends substantially for the full length of the pushing element 8, in particular for a length of at least 5 cm so as to come into contact with a preponderant portion of a segment 100. The contact portion 8a shown is in the form of a brush but it might be made from another compliant material or even a rigid material.

The transfer unit 4 described above may define a rejection unit for rejecting the segments 100 and, in such a case, the longitudinal groove 6 extends further downstream of the transfer unit 4 as far as an axial outfeed unit for the segments 100.

Alternatively, the transfer unit defines the outfeed unit of the segments 100. In such a case, the longitudinal groove may extend further downstream of the transfer unit 4 as far as a rejection unit for rejecting segments 100 that are defective or intended for inspection or, alternatively, a transverse rejection unit for rejecting the segments 100 upstream of the transfer unit 4. This invention lends itself to numerous modifications without departing from the scope of the inventive concept.

In particular, the longitudinal groove 6 is not an essential feature for the purposes of the invention. It may therefore be omitted and the segments 100 guided longitudinally directly onto a flat upper surface of the support beam 5 without appreciably altering the correct axial movement of the segments 100.

Figures 9-10 show two different embodiments where the longitudinal groove 6 is not present and where, preferably, the segments 100 are guided temporarily by the selfsame pushing elements 8 (or the single pushing element 8 in the case of the embodiment of Figure 8).

In these two embodiments, the pushing element 8 itself, and in particular, its end portion, in conjunction with other parts, defines means for longitudinally guiding the segments 100.

Looking in more detail, in the embodiment of Figures 9A and 9B, the support beam 5 is provided with a raised edge or step 5a at the rear of it (that is, opposite of the transverse outfeed direction of the segments 100) defining a rear stop for the segments 100 and preferably having a curvature radius substantially equal to the radius of the segments 100. In this configuration, the pushing element 8 (or each pushing element 8) can adopt a guiding configuration for the segments 100, defined by an angular position about the axis X ahead of the raised edge or step 5a (that is to say angularly offset forwardly relative to the impact configuration of Figure 4) such that a segment 100 is guided, at the back, by the raised edge or step 5a and, at the front, by a rear surface of the pushing element 8, the raised edge or step 5a and the rear surface of the pushing element 8 defining the aforementioned guide means. This configuration (Figure 9a) is, for example, set during machine start-up and is maintained stably so that one or more segments 100 to be rejected are conveyed longitudinally without being deflected transversely. On reaching a predetermined instant or following a command, the pushing element 8 is set in rotation to laterally deflect the segments 100 according to the operation described above (Figure 9B).

In the embodiment of Figures 10A and 10B, the support beam 5 is smooth (that is to say, without raised edges or guide recesses in the zone of longitudinal transit of the segments 100) and the segments 100 are longitudinally guided solely by the pushing element 8 which, at its free end, has a recess 8b facing towards the support beam 5 and defining, in conjunction with the support beam 5, a passage (or tunnel) for laterally retaining the segments 100 so that the segments 100 can slide longitudinally in a guided manner. Furthermore, the depth of the recess 8b is preferably such as to also guide the segments 100 vertically. More preferably, the recess 8b has an arcuate inside surface whose diameter, in particular, is substantially the same as the diameter of the segments 100. Moreover, the side walls radially terminating the recess 8b may be parallel to each other.

In this embodiment, too, the pushing element 8 (or each pushing element 8) can adopt a guiding configuration for the segments 100, defined by an angular position about the axis X angularly offset forwardly relative to the impact configuration of Figure 4) such that a segment 100 is guided in a longitudinal direction by the recess 8b, the recess 8b itself defining the aforementioned guide means. This configuration (Figure 10a) is, for example, set during machine start-up and is maintained stably so that one or more segments 100 to be rejected are conveyed longitudinally without being deflected transversely. On reaching a predetermined instant or following a command, the pushing element 8 is set in rotation to laterally deflect the segments 100 in he same way as described above (Figure 10B). The positions illustrated in Figures 9B and 10B, referred to the guiding configuration, may also be set during normal machine operation to reject one or more segments, which are conveyed longitudinally to a rejection station downstream.