The object of the invention is an apparatus for correcting shape of straw edges and a method for correcting shape of straw edges.

The food industry uses straws, which are usually made of plastic or paper, for drinking various types of beverages. They can be either one-piece or two-piece straws, straight straws or bendable straws. Plastic straws are made as a single piece, either straight or with an articulated part that allows it to be bent. The two-piece straws usually have in their structure a locking latch which connects the two parts so that, when unfolded to the using position, the beverage can be consumed without fear that the connection will be untight. This connection allows the straw to be folded, for example before the straw is wrapped in a foil from which the straw is removed before the beverage is consumed and unfolded to its maximum length. Such straws are called telescopic straws.

Telescopic straws and apparatuses for manufacturing such straws are known from the prior art.

The document EP 0 276 025 discloses a method of assembling a telescopic straw on a conveyor belt, inspecting and packing the individually assembled straws in a foil which is then welded. The document JP03827769 discloses an apparatus for assembling a telescopic straw of two parts which are placed in grooves of a drum conveyor. In that solution, a part of a straw with a larger diameter is slid over a straw with a smaller diameter by means of pushers whose sliding movement is forced by a cam. The locking latch of the straw is made by means of a ring which presses on the outer surface of the larger diameter straw. A frequently occurring problem in the state of the art is deformation of the straw edges in the process of cutting with circular knives. During the cutting process, the straw edge may be bent inwards, chafing of the straw edge may occur or the circular shape of the straw may be deformed so that it takes on for example an oval or ellipse shape. Such deformations cause an increase in the straw roundness error which may cause process difficulties or make the straw assembling process impossible. Correcting the shape of the straw edge is to be understood as acting on the straw in such a way as to minimize the roundness shape error, but also, in the case of a straw edge bent inwards, acting on the edge in such a way as to plastically deform it to obtain a diameter close to the nominal diameter of the straw B or even to deflect it partially outwards to allow the straw A to be easily inserted into it.

Other damage is also possible during the process of conveying the straws from one machine to another or during storage. Due to the thin walls of the straws, they can become deformed after being stored for a long time, in multiple layers on top of one other.

The object of the invention is an apparatus for correcting shape of edges of second straws comprising a conveyor provided with pockets adapted to convey straws situated in two paths transversely to a conveying direction, a displacing unit adapted to longitudinally displace the conveyed second straws in the pockets of the conveyor, and situated tangentially to the circumferential surface of the conveyed second straws, and an assembling unit for assembling the straws by inserting a first straw into a second straw. The apparatus is characterized in that correcting elements for correcting shape of the edge of the second straw are arranged between the conveyor pockets and adapted to inserting into the second straw, whereas the displacing unit is adapted to slide the second straw over the correcting elements for correcting shape of the edge. Preferably, in the apparatus according to the invention, the conveyor is a drum conveyor and the correcting elements for correcting edge shape are arranged on a ring.

Preferably, in the apparatus according to the invention, the conveyor is a drum conveyor and the correcting elements for correcting edge shape are arranged on a flange. Preferably, in the apparatus according to the invention, the correcting elements for correcting edge shape are mounted adjustably relative to the pocket of the conveyor.

Preferably, in the apparatus according to the invention, the correcting elements for correcting edge shape have a conical shape.

Preferably, in the apparatus according to the invention, the correcting elements for correcting edge shape have a spherical shape.

Preferably, in the apparatus according to the invention, the correcting elements for correcting edge shape have the shape of a pin with a rounded end.

Preferably, in the apparatus according to the invention, the correcting elements for correcting edge shape have the shape of a pin with a chamfered end. Preferably, in the apparatus according to the invention, the correcting elements for correcting edge shape are fixed substantially in the axis of the pocket of the conveyor.

Preferably, in the apparatus according to the invention, the correcting elements for correcting edge shape have an outer diameter of 90-120% of the inner diameter of the second straw.

The object of the invention is also a method for correcting the shape of an edge of a second straw, wherein the straws are conveyed in pockets in two paths transversely to the conveying direction, the straws are assembled by inserting a first straw into a second straw. The method according to the invention is characterized in that the second straws are slid over correcting elements for correcting edge shape situated between the pockets of a conveyor, by means of a displacing unit adapted to slide over the second straws, correcting the shape of edges of the second straws, whereas sliding the second straws over the correcting elements for correcting edge shape occurs before the first straws are inserted into the second straws.

Preferably, in the method according to the invention, the second straws are slid over the correcting elements for correcting edge shape by putting the second straws into longitudinal axial movement.

Preferably, in the method according to the invention, the second straws are slid over the correcting elements for correcting edge shape by putting the second straws into rotational motion. Preferably, in the method according to the invention, the shape of the edges of the second straws is corrected by making at least one rotation of the second straws about the longitudinal axis.

Preferably, in the method according to the invention, the shape of the edges of the second straws on the side intended for insertion of the first straws is corrected.

An advantage of the invention is a very simple and quick method of correcting the shape of the straw edges. By using the element correcting the shapes of straw holes, the straws can be mounted one inside the other without being subjected to deformation or damage. Furthermore, the correction of the shape of the straw edges significantly increases the efficiency of the manufacturing process by minimising the number of stops of the machine caused by the incorrect shape of the straw holes. The object of the invention is shown in more detail in a preferred embodiment in a drawing in which:

Fig. 1 shows an apparatus for correcting the shape of straw edges in a side view;

Fig. 2 shows a part of the apparatus for correcting the shape of straw edges in a top view;

Fig. 3 shows the moment of folding a straw with an incorrect edge shape;

Fig. 4 shows the first example of an incorrect edge shape of the straw B;

Fig. 5 shows another example of an incorrect edge shape of the straw B;

Fig. 6 shows another example of an incorrect edge shape of the straw B;

Fig. 7 shows another example of an incorrect edge shape of the straw B;

Fig. 8 shows the first embodiment of an element for correcting the edge shape;

Fig. 9 shows the second embodiment of the element for correcting the edge shape;

Fig. 10 shows another embodiment of the element for correcting the edge shape;

Fig. 11 shows another embodiment of the element for correcting the edge shape;

Fig. 12 shows the moment of inserting the straw B onto the element for correcting the edge shape;

Fig. 13 shows the moment of correcting the edge shape of the straw B;

Fig. 14 shows the moment of pulling out the straw B from the element for correcting the edge shape;

Fig. 15 shows the straw B after it has been pulled out of the element for correcting the edge shape;

Fig. 16 shows the straw B after correcting the edge shape in the first embodiment;

Fig. 17 shows the straw B after correcting the edge shape in the second embodiment;

Fig. 18 shows the process of folding the straw A with the straw B after correcting the edge shape;

Fig. 19 shows the element for correcting the edge shape together with an adjusting unit.

Fig. 1 shows an apparatus 1 for correcting the shape of an edge of a straw B in a side view. The apparatus 1 comprises a hopper 2, 3 for supplying the first straws of type A and the second straws of type B, the straws A being substantially longer and having an outer diameter smaller than the inner diameter of the straws B. Furthermore, one of the ends of the straw A may be bevelled at a preferably acute angle. In this embodiment, a drum conveyor 4 having pockets 5, 6 on its outer circumferential surface is shown. It is possible to have an embodiment wherein is used a belt or chain conveyor with pockets situated on the working surface conveying individually, parallel to each other, one after another longitudinally aligned pairs of the straws A and B. In order to implement the invention on the belt or chain conveyor, it is necessary to guide at least a part of the straw flow path along a guide of cylindrical shape.

Correcting the edge shape in the light of this invention is to be understood as acting on the straw in such a way as to both minimize the roundness shape error and adjust the diameter to proper dimensions required in the straw assembling process. In the first case, correcting the straw edge shape consists in deforming the straw edge to minimise the roundness error, e.g. by deforming a straw deformed in storage with a near elliptical cross-section to a near circular cross-section with a diameter that allows the straws A and B to be correctly assembled.

In the second case, correcting the shape consists in deflecting the straw edge bent inwards, e.g. when the diameter is too small, and acting on the edge of the straw in such a way as to plastically deform it to a diameter that allows the straws A and B to be correctly assembled.

Shape correcting is also to be understood as a shape correction operation comprising both shape correcting to compensate for roundness error and deflecting the inwardly bent straw edge.

All these functions are performed by correcting elements 7 according to the present invention. The hopper 2 and 3 is placed above the conveyor 4, tangentially to its working surface, so that during the rotation of the conveyor 4, the straws A and B are picked up from the hopper 2 and 3 into the pockets 5, 6. The straw A placed in the pocket 5 is directed by its bevelled end towards the straw B aligned with it longitudinally and placed in the adjacent pocket 6, the straws being conveyed transversely to the conveying direction. Then, during the rotation of the conveyor 4 in the direction indicated by the arrow Ri, the straws B are displaced in the direction of the edge shape correcting element for correcting straws B, as shown in detail in Fig. 2. Further in the description, the edge shape correcting elements 7 will be referred to as correcting elements 7. The correcting elements 7 are positioned between two paths for transporting the straws A and the straws B on a ring 8, substantially coaxial with the pockets 6 and the straws B. Furthermore, the ring 8 is situated on the same axis X as the conveyor 4 between the pockets 6 and 5. In this embodiment one correcting element 7 is assigned to each of the pockets 6. It is also possible to have an embodiment where the number of the correcting elements 7 will be smaller than the number of the pockets 6 situated on the circumference of the conveyor 4. In such a case, the correcting elements 7 will move in a loop overlapping for a certain section of their path with the path of the pockets 6 of the conveyor 4 where they will reach a position of momentary alignment with the grooves 6.

It is also possible to build such conveyor 4 wherein, between the pockets 5 and 6, there will be a conveyor flange on which, on the side of the pockets 6, there will be the correcting elements 7 having a longitudinal axis aligned with the axis of the pocket 6. In one embodiment, the edge shape correcting elements 7 are fixed adjustably relative to the pocket 6 of the conveyor. There are feasible embodiments wherein the edge shape correcting elements 7 have a conical or spherical shape, a shape of a pin with a rounded end or a shape of a pin with a chamfered end.

In the shown embodiment of the apparatus 1, the straws B are displaced in the direction of the correcting elements 7 by means of a displacing unit 20. Furthermore, the displacing unit 20 comprises a roller 9 with a concave working surface, positioned above the conveyor 4 tangentially to the straws B conveyed in the pockets 6 on its circumferential surface and substantially perpendicular to the axis X. The concave shape of the working surface of the roller 9 and the substantially perpendicular orientation relative to the conveyed straws B in the pockets 6 of the conveyor rotating in the direction Ri causes the straws B to be put into rotation about their longitudinal axes coinciding with the longitudinal axis Xi of the pocket 6. Furthermore, whilst the roller 9 contacting with the conveyed straws B, the roller 9 is put into rotation in the direction Ti by means of a drive not shown in the figure. This solution makes it possible to adjust the speed of rotation of the roller 9, and thus the distance over which the straws B is arranged to move along the axis Xi Furthermore, the time, the number of rotations of the straw B when mounted on the correcting element 7 and the force of pressure of the straw B on the pin of the correcting element 7 can be adjusted as required, depending on the type of deformation of the end of the straw B to be corrected. There is a feasible embodiment wherein, after sliding the straw B over the correcting element 7, the shape of the edge 14 of the second straw B is additionally corrected by making at least one rotation about the longitudinal axis of the second straw. Preferably, the shape of the edge of the second straw B is corrected on the side intended for the insertion of the first straw A.

After a sufficient number of rotations of the straws B on the correcting element 7, the straws B are slid down therefrom and displaced axially longitudinally in the pockets 6 towards the lateral edge of the conveyor 11. Sliding down and longitudinal displacement in the pockets 6 is forced by a roller 10 with a concave working surface which, like the roller 9, is situated above the conveyor 4 tangentially to the straws B conveyed in the pockets 6 on its circumferential surface and substantially perpendicular to the axis X. The roller 10 rotates in the direction T2 _, opposite to the movement of the roller 9. After the longitudinal axial displacement of the straws B to the edge 11, the straws are conveyed to the assembling unit 12 on which the straws A are assembled in the straws B. The rollers 9 and 10 are positioned tangentially to the circumferential surface of the conveyor 4 in such a way that the working surfaces 9 and 10 of the rollers are in contact with at least three straws B situated in adjacent pockets 6.

When mounting of straws A in the straws B, there may occur a problem with inserting the straw A into the straw B due to an incorrect shape of the edge 14 of the hole 13 of the straw B, as shown in detail in Fig.3. The incorrect shape of the edge 14 of the hole 13 may arise during the earlier process of cutting the straw B with a circular knife resulting in the folding of the edge 14 inwards the straw. In such a case, the edge 15 of the straw A collides with the edge 14 of the straw B when the straw A is inserted towards the straw B which is aligned with it.

Other damage is also possible during the process of conveying the straws from one machine to another or during storage. Due to the thin walls of the straws, they can become deformed after being stored for a long time, in multiple layers on top of one another. Figs. 4 -7 show examples of deformation of the shape of the hole 13 of the straw B in a cross-section and in a front view. The deformations shown are not a closed group of defects that may occur and affect the shape of the edge 14 of the hole 13 of the straw B.

In order to eliminate the mentioned problem of the incorrect shape of the edge H of the hole 13 of the straw B, the correcting elements 7 are provided in the apparatus 1. The correcting elements 7, in this embodiment, are situated on the ring 8, on its lateral surface 16.

In Figs. 8-11, only examples of shapes that the correcting elements 7 may have are shown, and they do not constitute a closed group. An important feature of the invention is that the correcting element 7 enters through the hole 13 of the straw B, at least partially inside the straw B while correcting the shape error of the edge 14. The outer diameter Di of the correcting element 7 should correspond to 90-120% of the value of the inner diameter D2 of the straw B.

In order to eliminate shape errors of the edge H of the straw B, by means of an assembling element, in this embodiment of the roller 9, the straws B are slid over the correcting elements 7 which are positioned between two axially aligned pockets 5 and 6. Fig. 12 shows the moment of mounting the straw B put in rotational and longitudinal motion axially onto the correcting element 7. When mounting the straw B onto the correcting element 7 the shape of the incorrectly formed edge 14 is corrected as shown in Fig. 13 and Fig. 17. Depending on the final effect of the shape of the edge 14 to be obtained, the straw B may be mounted deeper onto the correcting element 7 by making both longitudinal and rotational movement at the same time. Such adjustment of the shape of the edge 14 as that shown in Fig. 14 -16 is also allowable. The deflection of the edge 14 should be great enough to allow an easy insertion of the straw A into it. Then the straw B is slid down from the correcting element 7 by means of the roller 10 not shown in the figure and is transferred to a further process of assembling the straw A into it as shown in Fig. 18. After the process of correction of the shape of the edge 14, the straw A is inserted, in a collision-free manner, into the straw B. The correction of the shape uses the phenomenon of plasticity and formability of the paper of which the corrected straws are made.

Fig. 19 shows the correcting element 7 together with an adjusting unit 17 enabling the correcting element 7 to be appropriately positioned relative to the axis Xi of the pocket 6.

The position of the ring 8, on which the correcting elements 7 are placed, can be adjusted relative to the pocket 6 along the axis Xi, for example when a straw B of changed length is used in the straws assembling process. Furthermore, the ring 8 can also vary its position transversely to the axis Xi, for example when a straw B of changed diameter is used in the straw assembling process.

In order to vary the position of the ring 8, an adjusting unit 17 comprising a controller 18 transmitting appropriate signals to actuators 19 varying the position of the ring 8 may be used.

It is also possible to manually vary the position of the ring 8 between the pockets 5 and 6 of the conveyor 4, for example by using spacer rings on one or both sides of the ring 8.

In this case, before any variation in the length of the assembled straws, a spacer ring, which increases or reduces the distance of the correcting element 7 from the pockets 5, 6, is placed between the portion of the conveyor 4 containing the pockets 5 and/or 6 and the ring 8.

The invention makes it possible to increase the paper straw assembling efficiency by eliminating geometric collisions encountered in state-of-the-art solutions and resulting from the cutting, conveying or storing process. The introduction of the shape correction immediately before or at a small processing distance preceding the assembling operation allows applying small forces and a gentle interference with the material. According to the invention, the effects of the shape correction need not be permanent, nevertheless they must persist for a period of time allowing the transfer to the assembling unit. Since the shape correction according to the invention takes place individually for straws already prepared in the processing operation preceding the assembling, the fulfilment of the time condition is simple and the applied shape correction forces can be small.