A machine and a method for packaging with cardboard strips

Abstract

 A machine and a system for packaging products in cardboard strip, wherein a dynamic grouping system (300) sorts the products (P) with a predetermined machine pitch (C), in an advancing direction (A); at least two feeding groups (200, 201) are arranged in line with respect to said advancing direction (A) and operate synchronously, each depositing a strip inside the pitch of a strip conveyor system, synchronised with said machine pitch.

Description

Field of application

[0001] The invention refers to the technical field of the packaging with cardboard strips, in particular in the food and beverage industry.

Prior art

[0002] Packaging with cardboard strips is widely used in the packaging of food products. The cardboard strip is a die-cut cardboard that is suitably folded over on itself and groups together a certain number of articles or products, for example primary containers such as bottles, glass jars, thermoformed jars, etc... obtaining a sales unit. For example, the grouping can be x2 (two articles enclosed in a strip), x4, x6, etc... The products can be arranged in two rows, for example a x6-grouping usually comprises two parallel rows of three products.

[0003] This packaging system allows to form multiple sales units of various formats and improves the presentation of the product, since the strip is a convenient support for high-quality colour printing of markings, trademarks and other information for the consumer.

[0004] A prior-art machine for packaging with cardboard strips essentially comprises, in order, the following subgroups:

• at least one conveyor continuously feeding the products, for example glass or plastic jars, with a feeding speed V1, equal to a characteristic dimension such as diameter or length of one article, multiplied by the number of pieces per minute;
• a dynamic grouping assembly, which essentially acts to set a certain machine-pitch for the products continuously fed by the conveyor, producing an output of spaced-apart batches, and which can be made for example with a system of star-conveyors and side jaws picking up the products and carrying them to a speed V2 equal to the machine pitch multiplied by the number of batches per minute, said speed V2 being generally greater than the speed V1 defined above;
• an assembly for handling the cardboard strips essentially comprising a storage container and a cardboard strips feeding group, the latter being arranged to pick up the cardboard strips from the storage container and transfer them to a transportation and piling group, the number of pickups per minute corresponding to the batches coming from the dynamic grouping assembly;
• an assembly for folding and closing the strip around the products.

[0005] The cardboard strip feeding group is generally made with a vacuum picking member mounted on a rotary support. The picking member takes the strips from the storage container and arranges them on the batches below, generally turning over the strips with an almost complete rotation, close to 360 deg.

[0006] Referring, for example, to a specific embodiment of the prior art, the operation is the following: products continuously fed by the conveyor are phased by two star-conveyors and then laterally gripped by the jaws of the dynamic grouping assembly, producing a flow of spaced-apart batches, one batch comprising a given number of products, for example four products per batch, and proceeding with a speed V2. The machine pitch, in practice, is equal to the distance between two consecutive jaws.

[0007] The products, while gripped by the jaws, accelerate from speed V1 to a greater speed V2. Said acceleration is a limit to the productivity of the machine. Indeed, there is a maximum acceptable acceleration for the products or their packages, beyond which they can get damaged or broken. Damaged or even deformed products can cause a jam-up of the transportation system and expensive downtime; glass containers, if subjected to an excessive acceleration, can even explode with risks to the safety of the operators. Hence, for a given feeding speed V1 there is an upper limit to the speed V2 and, consequently, to the output of the machine.

[0008] This limitation is felt especially when the machine is required to operate both in a "short" and "long" configuration for a given machine pitch. The limit to speed V2 is more strict while working with a short configuration, for example with a x2 grouping, in comparison with the operation with a longer grouping, for example x6. For a given feed from the conveyor, the short configuration gives a higher speed of the grouping jaws and, consequently, stresses the products with a greater acceleration. The speeds V1 and V2 can be calculated in the following way:




being apparent that for a given speed V1, the speed V2 is greater for a less numerous grouping batch.

[0009] The cardboard strip feeding group, and in particular the respective picking member, can also constitute a bottleneck for maximum speed of the machine, especially due to the wide rotation movement imposed to the strips. At a high speed, the mechanical stress undergone by the cardboard strips requires to adopt a more expensive cardboard with greater rigidity and weight. Moreover, since the strips need to be more rigid, more difficulties are encountered in the handling of strips equipped with perforations or cutting lines; perforations or cutting lines, however, are often required by the market, for example to allow the consumer to easily separate the products in a multiple package.

[0010] Conventional cardboard strips feeding apparatuses with a high efficiency have been developed, but they only partially solve these problems, with the drawback of a much higher cost, and in any case they cannot solve the problem of productivity limited by the maximum acceptable acceleration of the products.

[0011] Other systems for dynamic grouping are known, in particular flight lateral conveyors and worm screw conveyors, which do not however solve the problems outlined above, or introduce others. The flight conveyors, compared to jaw systems, are limited in that they are not adapted to format change and do not allow to house every product in a specific seat. Worm screw systems could theoretically avoid the problem of the ratio between speeds V1 and V2, defined above, by adopting a predetermined profile of the screw(s) to group together the products with predetermined configurations, but suffer heavy limitations in the format change as the configurations vary; moreover, due to their physical/mechanical features, worm screws are only suitable for products having a low height, less than 20-30 mm (e.g. canned tuna).

[0012] For these reasons, in known machines the production speed is generally limited to about 300-350 pcs/min. However, the need for higher speeds is more and more pressing, especially in the food industry. The machine must also maintain a flexibility of configuration, allowing to quickly change the number and/or arrangement of the products packaged in each strip (format change).

Summary of the invention

[0013] The invention has the purpose of overcoming the limitations outlined above and in particular to improve the efficiency of the step of positioning the strips, and thus of the relative feeding group, so as to: allow high productivity without subjecting the products to excessive acceleration in the dynamic grouping step, especially for small configurations; operate at high speeds without requiring rigid strips of high-quality cardboard, but instead accepting e.g. strips of medium-weight cardboard and/or cardboard strips equipped with perforations.

[0014] The idea underlying the invention is to feed the strips with at least two feeding groups, arranged in line with respect to the advancing direction of the products, and operating synchronously, depositing the strips on a conveyor synchronised with the machine pitch of the products. Consequently, the invention allows the grouping of a maximum number of products for each product batch, and wrapping the products with one or two strips of equal or different dimensions, according to the configuration.

[0015] These aims are reached with a machine for packaging products in cardboard strip, comprising:

• at least one conveyor of products and a dynamic grouping system capable of forming batches of said products with a predetermined machine pitch and with an advancing direction along the machine;
• at least two cardboard strips feeding groups each comprising a storage container and a cardboard strips picking member;
• a strip conveyor system and a group for folding and closing the strips;
• the feeding groups being arranged in line with respect to the advancing direction of the products and operating synchronously, each of the feeding groups depositing a respective strip on said strip conveyor system;
• said strip conveyor system having a transportation pitch of the strips synchronised with said machine pitch, when the packaging machine is operating.

[0016] According to a preferred embodiment, the strip conveyor system comprises a double side conveyor with side-by-side transporters under respective feeding groups. More preferably, the conveyor extends at least partially above the dynamic grouping system, said grouping system being for example equipped with jaws.

[0017] The feeding groups rotate preferably with the same direction of rotation, each comprising preferably a vacuum picking member supported by a rotary disc.

[0018] According to another aspect of the invention, thanks to the in-line arrangement of the two feeding groups, the picking member of each feeding group operates by arranging the strips from the storage container to the conveyor below with a rotating-translating trajectory, the rotation being less than 180 degrees, and preferably about 90 degrees, with further advantages compared to systems that operate by turning over the strips during the transfer from the storage container to the strip conveyor.

[0019] In accordance with the invention, the strips positioned by the two feeding groups can be identical or different.

[0020] In a first operating mode, the two feeding groups arrange two strips having equal length, for example equal to two products, for each operating cycle. In a second mode, which is possible thanks to the invention, the first feeding group positions first strips of a given length, for example equal to two products, and the second group positions second strips of a different length, for example equal to that of one product, provided that the sum of the lengths of the first and second strips, positioned in each cycle, must not exceed the pitch set by the dynamic grouping system.

[0021] Another aspect of the invention is that the picking members of the feeding groups can be arranged to pick up the strips at the same contact point, thanks to the in-line arrangement of the feeding groups and to the synchronized rotation of the holding members. This makes possible to use strips with a complex shape and/or with openings, with a secure pick-up by both of the feeding groups.

[0022] In accordance with invention, a method for packaging products in cardboard strip comprises the steps of:

• dynamic grouping of the products in batches with a predetermined machine pitch;
• positioning of strips of cardboard on a conveying system, through at least two feeding groups arranged in line in the advancing direction of the products, said feeding groups operating synchronously,
• each strip being positioned on said conveying system with a conveying pitch less than or equal to the predetermined machine pitch in the dynamic grouping step of the products, and synchronised with said pitch,
• where the sum of the lengths of the strips positioned within said conveying pitch does not exceed said machine pitch of the batches of products.

[0023] The method, for each batch of products or rather within the machine pitch, allows the positioning of strips of cardboard of equal dimensions, or else of at least two strips of cardboard having a different length in the advancing direction of the products. In this second case, the sum of the lengths of the strips is less than or equal to said machine pitch.

[0024] The machine according to the invention can reach higher production speeds, compared to the prior art, substantially because the duty of positioning the cardboard strips is spread between the at least two feeding groups. Consequently, a reasonable phasing speed of the products is maintained also when operating with small configurations at high production speed, without affecting the feeding member or requiring high quality cardboard.

[0025] The invention allows the dynamic grouping system to operate by picking up the maximum number of products compatible with the machine pitch, for each batch, keeping the speed V2 at an acceptable value. According to the operating mode the batches can receive a single strip or two or more strips, identical or different. In this way, the differential V1-V2 is limited since the dynamic grouping system always operates at the maximum of its capability, dealing with products feed from the conveyor without having to increase V2 too much. Since, as stated above, there is a maximum value of the V1-V2 differential that can be borne by the products, the invention reaches a higher productivity compared with the prior art, for the same V1. For example, in cases where a prior-art machine reaches about 300 pcs/min, a machine according to the invention can operate at 400-500 pcs/min with the same safety margin.

[0026] Starting from the same grouping of products, a machine according to the invention reaches an output of packages that is equal to the number of groupings when each batch is wrapped by a single strip, or double when each batch is wrapped by two adjacent strips, without varying the differential between V1 and V2. This feature shall be more evident with the help of the examples.

[0027] The particular movement of the two feeders for picking up the strip by flipping in the clockwise direction, which forms one of the aspects of the invention, allows mechanization of die-cut pieces of substantial size, without imposing to the cardboard strips the almost complete rotation occurring in the prior art. Moreover, the feeders have the same pick-up point on the strip, and this is an advantage when the strips have a complex shape with holes, die-cuts, cutting lines, etc... Indeed, the pick-up point of both feeding groups falls in a "full" area of the strip without openings, die-cuts, etc... thus being suitable for the holding action of the picking member.

[0028] These and other advantages of the invention shall become clearer with the help of the following description, referring to a preferred embodiment.

Brief description of the figures

[0029] 

Fig. 1 shows the main groups of a machine according to a preferred embodiment of the invention.

Figs. 2 to 5 show the groups of Fig. 1 in greater detail.

Fig. 6 shows the operating principle of the feeding groups of the machine of Fig. 1.

Fig. 7 schematically shows some examples of ways of operating of the machine of Fig. 1, with reference to the positioning of the strips on the batches of products.

Detailed description of the invention

[0030] Fig. 1 shows a machine for packaging with cardboard strips comprising: a belt conveyor 100 feeding products such as for example bottles or jars; two cardboard strips feeding groups generally indicated as 200 and 201 and in line with the advancing direction A of the products along the machine; a dynamic grouping system 300 capable of giving a predetermined machine pitch to the products fed from the conveyor 100; a conventional unit 400 for folding and winding the strips.

[0031] The conveyor 100 is a known item and can feed the products, for example, in a single or double row on a conveyor belt.

[0032] Fig. 2 shows details of the grouping system 300 that essentially comprises a pair of star conveyors 301 and 302 and a group 303 with side jaws 304, having a grouping pitch C. The products are depicted as jars P.

[0033] The stars 301 and 302 are moved by a suitable motor, and have the function of feeding the products P with a certain rate synchronised with the pick-up speed of the downstream group 303. The stars are formed essentially with a disc carrying a series of arc-shaped recesses 313, each being sized to receive one of the jars P. In this way, the stars 301 and 302 output a flow of products P, synchronised with the picking-up action of the group 303. The stars are not described any further since they are per se known.

[0034] The group 303 comprises a plurality of jaws 304, on opposite sides, transported in a closed path by a motorised belt 305. Each jaw 304 is formed with a certain number of seats or recesses 306 suitable for receiving one of the products P.

[0035] Two opposite jaws 304a and 304b, closing against one another at one end 320 of the group 303, immediately downstream of the stars 301 and 302, form a batch of products. In the example of Fig. 2, a batch is represented by six units of the products P. The jaws 304 proceed in the advancing direction A, opening at an opposite end 321 of the group 303, and then returning to the pick-up end 320.

[0036] The machine-pitch C is equal to the distance between corresponding points of two subsequent jaws 304, as shown in the figures, and is the physical distance between the batches of products advancing in the group 303. It should thus be noted that the products P go from the continuous flow on the conveyor 100, to a regulated batch flow with the pitch C set by the group 303.

[0037] The assembly of the feeding groups 200 and 201 is shown in Fig. 3. Each group essentially comprises a storage container 210, 211 for the cardboard strips, with a withdrawal window 212, 213, and a pick-up member 215, 216.

[0038] The member 215 for picking up and positioning the strips of the first feeding group 200 essentially comprises a disc 220 that eccentrically carries a rotary support for one or more holding members 223 (Fig. 4), operating under depression (vacuum).

[0039] The number of said holding members supported by the disc 220 can vary according to the format of the strips and the required speeds. Generally one to five members are supported by the disc 220. In the example, the disc 220 carries three holding members made as arms 223 equipped with vacuum holders 224, connected to a vacuum system. The member 216 of the second feeding group 201 is made in the same way.

[0040] The members 215 and 216, during operation, deposit the strips on an underlying side conveyor 230, 231, which preferably is of the type with "flights". Each conveyor comprises two side-by-side transporters 232a, 232b and 233a, 233b, below the respective feeding groups 215 and 216. Said transporters comprise two overlying belts and carry a series of pushing elements 234, known as flights, which guide forwards the cardboard strips released by the pickups 215 and 216, in the direction of travel A of the machine. The conveyors are operated by respective motors 235.

[0041] Fig. 5 shows the positioning of the feeding groups 200 and 201 with respect to the grouping assembly 300. It should be noted the short length of the assembly 300 obtained with the invention, which does not exceed the physical limit of the last feeding group in the advancing direction A, said last feeding group being the second group 201 in the figures. It is worth noting from Fig. 5 the particular arrangement of the groups, unlike the prior art in which the grouping assembly generally precedes the feeding group, in the advancing direction of the machine.

[0042] The preferred way of operating of the feeding groups is schematised in Fig. 6. The feeding members 215 and 216 rotate in the same direction, in the example in the clockwise direction R; the positioning of the strips takes place with a rotating-translating movement, by the rotation of the disc 220 and of the support of members 223. A strip 240, which is located in the storage container 210 (or 211) and is positioned on the window 212, is gripped and moved with a trajectory indicated by the positions a), b), c) d) and e) of Fig. 5, with a rotation in the direction W of figure, which is about 90 degrees from the almost vertical pick-up position to the horizontal travel position on the conveyor 230 below. This way of moving the strip 240 brings the following advantages: the stress of the cardboard strip is less severe due to reduced angle of rotation, and consequently it is possible to use a medium-weight cardboard not too expensive; the two groups 215 and 216 can operate in substantial symmetry, by applying the respective suckers 224 exactly in the same point of the strips present both on the window 212 of the first storage container, and on the window 213 of the second storage container. In this way it is possible to adopt strips with complex shapes and/or with openings for example for the packaging of bottles.

[0043] During operation, the transporters 232a, 232b and 233a, 233b are phased and synchronised with the grouping system 300 and in particular with the jaw group 303. In this way, the pickup members 215 and 216, cooperating with the side conveyors 230 and 231, can deposit one or two strips of cardboard inside the machine-pitch C of the products P.

[0044] Possible example ways of operating are schematised in Fig. 7. In example A), the jaws 304 form batches of six products P, and the groups 200, 201 position a strip 240 on each batch; in example B) two identical strips 241 are positioned per batch of six products, obtaining two packs of three; in example C) the same jaws work for partial filling and form batches of four products, wrapped with two identical strips 242 respectively positioned by the groups 200 and 201; in example D) the batches of five products each are wrapped with a first strip 243 positioned by the first group 200 and a second strip 244 positioned by the second group 201, the two strips 234 and 244 being of different lengths, in direction A. In all cases the sum of the equal or different lengths of a pair of strips positioned by the groups 200 and 201 on a batch of products P, does not exceed the machine pitch C.

[0045] The wrapping of the strips is completed in the group 400 (Fig. 1) closing the strips with glue or coupling.

[0046] The following are two specific examples of operation of a machine according to the invention are given, purely for indicating purposes.

EXAMPLE 1

[0047] A machine according to the invention receives a flow of products P from the feeding conveyor 100 at 1.200 pcs./min. The pieces have a size of ∅ 55 mm and a speed V1 of 66 m/min. The system 303 has a pitch of 380 mm and packages batches of 6 pieces each in single row configuration, carrying them at a speed of 76 m/min equal to an output of 200 packs/min. Each of the feeding groups 200 and 201 deposits 100 strips/min. for each machine pitch for a length equal to at least 330 mm and therefore occupying almost all of the pitch. The example shows the advantage of treating strips of substantial length at a speed of 200 packs/minute.

EXAMPLE 2

[0048] The same machine according to Example 1 receives the same flow of products P ∅ 55 mm from the conveyor 100 at 1,200 pcs./min and speed V1 of 66 m/min. The system 303 with pitch of 380 mm packages the pieces with batches of 3 pieces in single row configuration each starting from a grouping of 6 pieces, carrying them at a speed of 76 m/min equal to an output of 400 packs/min. Each of the feeding groups 200 and 201 deposits 200 strips/min. for every portion of machine pitch for a length equal to at least 2x165 mm. This displays the advantage of having doubled the output of the machine at considerable speeds without having changed the differential between V1 and V2, thanks to a single change in operation and replacement/adjustment of the withdrawing window of the die-cut piece 212.

Claims

1. Machine for packaging products with cardboard strips, comprising:

a) at least one conveyor (100) of products (P) and a dynamic grouping system (300) capable of forming batches of said products (P) with a predetermined machine pitch (C) and with an advancing direction (A) along the machine;

b) at least two cardboard strips feeding groups (200, 201) each comprising a storage container (210, 211) and a holding member (215, 216);

c) a strip conveyor system (230, 231) and a strip folding and closing group (400);

d) the cardboard strips feeding groups (200, 201) being arranged in line with respect to the advancing direction (A) of the products and operating synchronously, each of said feeding groups depositing a respective cardboard strip on said strip conveyor system;

e) said strip conveyor system having a transportation pitch of the strips synchronised with said machine pitch (C), when the packaging machine is in operation.

2. Machine according to claim 1, said strip conveyor system comprising a double side conveyor (230, 231) with side-by-side transporters (232a, 232b; 233a, 233b) below the respective feeding groups (215 and 216).

3. Machine according to claim 1 or 2, said strip conveyor system extending at least partially above said dynamic grouping system (300).

4. Machine according to claim 1, 2 or 3, each of said feeding groups comprising a holding member (215, 216), said holding members rotating in the same direction (R).

5. Machine according to claim 4, where said feeding groups (215, 216) operate in such a way as to withdraw and position a strip (240) from the respective storage container (210, 211) to the conveyor (230, 231) with a rotating-translating trajectory, having a rotation component below 180 degrees and preferably of about 90 degrees.

6. Machine according to claim 5, the holding members (215, 216) of said feeding groups (200, 201) having the same pick-up point of the strips with respect to pick-up windows (212, 213) of said storage containers (210, 211).

7. Machine according to any one of the previous claims, said dynamic grouping system (300) comprising a pair of star conveyors (301 and 302) and a group (303) with side jaws (304).

8. A method for packaging products (P) in cardboard strip, comprising the steps of:

- dynamic grouping of the products (P) in batches with a predetermined machine pitch (C);

- positioning of strips of cardboard on a conveying system, through at least two feeding groups (200, 201) arranged in line in the advancing direction (A) of the products (P), said feeding groups (200, 201) operating synchronously,

- each strip being positioned on said conveying system with a conveying pitch less than or equal to the predetermined machine pitch (C) in the dynamic grouping step of the products, and synchronised with it,

- the sum of the lengths of the strips positioned inside said conveying pitch not exceeding said machine pitch (C) of the batches of products (P).

9. Method according to claim 8, comprising the positioning of two strips of cardboard of equal dimensions (240, 241, 242) on each batch of products.

10. Method according to claim 8, comprising the positioning of at least two strips of cardboard (243, 244) on each batch of products, the two strips having different lengths in the advancing direction (A) of the products, the sum of the lengths of said two strips being less than or equal to said machine pitch.

Drawing