Perfected machine and method for packaging in extensible film products fed in groups or individually

A packaging machine using extensible film for products fed in groups or individually includes a conveyor feeding the product, a product positioning unit, a film winding unit and a discharge conveyor positioned at the outlet of the winding unit. The winding unit is a ring winder having a ring rotating with respect to guiding rolls, positioned on a supporting frame, and arranged on a plane perpendicular to the advance direction of the products. A shelf is provided beneath the winding unit, cantilevered for extending in the advance direction of the products, and connects the feeding conveyor with the winding unit. A vacuum-effect gripping unit is positioned beneath the shelf for gripping the film and carries a cutting unit. The vacuum-effect gripping unit and the cutting unit can be moved alternatingly and selectively from a withdrawn rest position of the shelf to an extended position for gripping and cutting the film.

The present invention relates to a perfected machine and method for packaging products in extensible film, fed in groups or individually.

In the field of packaging of various types of products fed in groups, such as, for example, bottles, boxes of various sizes, etc., a film of plastic material of the shrinkable type treated by a specific machine, is currently mostly used. This film is wound around the product or groups of products, then welded and cut to size and subsequently inserted in a heat shrink oven which stabilizes the packaging thus obtained, keeping the products stably in its interior.

This kind of technique implies a certain cost for plastic material having a certain thickness, a cost for the energy used for the heat shrinking in addition to a plant cost which requires the presence of a packaging machine and relative heat shrink oven associated with the same. Last but not least there is a further increase in costs due to the considerable time necessary for obtaining the final heat-shrunk packaging of products.

As an alternative, a film of extensible plastic film can be used for the packaging which is wound around the products. The products are divided into groups and selectively wound in correspondence with a winding unit. In this winding unit, a reel of extensible plastic film is rotated around the products carried by a conveyor belt or roller conveyor and, at the end of the winding, the packaging thus obtained is discharged. The cutting of the film after being wound around the products and the repositioning of the film to prepare it for being wound around a subsequent new group of products to be packaged, creates various problems in this packaging unit.

This problem is particularly felt in the case of a ring winding machine, which is particularly fast and functional.

WO 2015/121334 relates to a packaging machine with extensible film in which a shelf is provided, which receives the corresponding products to be packaged. An elongated hollow element is positioned above the shelves, which ends laterally close to the packages being packed and externally has at least one suction opening. Separately and below the shelf, in a withdrawn position with respect to the other elements of the machine, a retaining clamp of an edge of the film is provided which also cuts said film.

The general objective of the present invention is to provide a perfected packaging machine in extensible film, of products fed in groups, capable of solving the above drawbacks of the known art in an extremely simple, economical and particularly functional manner.

A further objective of the present invention is to provide a packaging machine which can function almost continuously, at a high rate, without any cutting or insertion interventions of the film which is being wound around the group of products, eliminating any kind of stoppage in the packaging phase and operating almost automatically.

Another objective of the present invention is to provide a packaging machine of products which, by using an extensible film, reduces costs relating to the packaging material.

Yet another objective of the present invention is to provide a packaging method which can function almost continuously, at a high rate, without any cutting or insertion interventions of the film which is being wound around the group of products, eliminating any kind of stoppage during the packaging phase and operating almost automatically.

The above objectives are achieved by a machine and method produced according to the independent claims and following subclaims.

With reference to the figures, these show a perfected packaging machine in extensible film of products fed in groups, such as bottles, boxes or other objects, or individually as single products11, the machine being indicated as a whole with10.

It should be considered that, upstream of this machine10, the single products11can be positioned in order, for example on a certain number of rows, aligned and adjacent or as a single product. Hereinafter reference will be made to “product11” even when there are various products. Consequently, the product11is moved forwards up to a feeding conveyor12of the packaging machine, for example a conveyor belt.

The machine of the invention essentially comprises the conveyor12for feeding the product11, a positioning unit13of the product, a film winding unit14of the single product or groups of products and a discharge conveyor15positioned at the outlet of the winding unit14, for example a conveyor belt.

In short, the product11coming from an upstream movement or charged manually, reaches the belt conveyor12at the inlet. The conveyor belt12can be in line (not shown) or at 90° (as in the example illustrated) with respect to the linear positioning group13. In this way, the product11, when it has reached the conveyor belt12in correspondence with the positioning unit13, it is moved inside the winding unit14, simultaneously pushing the product11which has been wound in the previous cycle onto the discharge conveyor belt15which, thus packaged, discharges it. Once the positioning of the product to be wound has been completed, the winding cycle is initiated. The reference production capacity, which also depends on the type of product, can be about 10-12 packages/min.

More specifically, a bridge structure is positioned downstream of the conveyor belt12and before the winding unit14, which receives the product11to be wound for creating the final packaging or package. Said bridge structure comprises a shelf16cantilevered for extending from a supporting frame17, according to the advance direction of the product11. The shelf16connects the conveyor belt12with the subsequent winding unit14. Pairs of side guiding bars38, also cantilevered to form the bridge structure, keep the product11in line, compact and orderly, if there is more than one.

The shelf16cantilevered and extending from the frame17is such as to enable a vacuum-effect gripping unit18to be movably positioned beneath it. The shelf16is also such as to facilitate the sliding of the film when, once wound onto the product, it slips off the shelf before being expelled through the positioning unit13.

As already indicated, the shelf16is positioned near the winding unit14. The winding unit14comprises a frame19, positioned astride with respect to the product11arranged on the shelf.

The ring winding unit14comprises a ring or slewing ring20which rotates with respect to guiding rolls21, positioned on the frame19. Said ring20is arranged on a plane perpendicular to the advance direction of the product11. A motor reducer22integral with the frame19, controls the rotation of the ring20by means of a controlling friction roller23.

A reel holder24for a reel25of extensible plastic film is assembled integral with the ring20. A support26of a rubberized tensioning roller27and a pair of return rollers28for the film are associated with this reel holder24. The tension of the film being unwound can be regulated, by means of a brake (not shown) for example, which acts directly on said rubberized tensioning roller27.

During the winding process of the film around the product11, the rotating ring20rotates for a programmable number of turns to allow the correct quantity of film to be deposited.

As already indicated, according to the present invention, the extensible film close to the winding group14is withheld by a vacuum-effect gripping unit18. Said vacuum-effect gripping unit18can be moved from an extended position beneath the shelf16carrying the product11to be wound or already wound (FIG. 7) to a withdrawn rest position of the shelf16(FIG. 6) after releasing the film wound onto the product. The vacuum-effect gripping unit18is in fact withdrawn, releasing the film after the winding ring20has effected various turns so as to fix the film to the product(s)11. During the last of these turns, the gripping unit18re-exits and, as the film passes, it sucks it, withholding it (FIG. 9), and also cuts it with a cutting element such as a hot blade brought into contact with the film by means of a rotating movement (FIGS. 8 and 10).

More specifically, the vacuum-effect gripping unit18, shown in greater detail inFIGS. 11 to 14, comprises a hollow tubular section29. A vacuum is created in said hollow tubular section29and, thanks to the presence below of suction holes or sectors30, it holds the film in a gripping position. Laterally, the hollow tubular section29carries a cutting element in the form of a cutting blade31for the same film. Said hollow tubular section29and consequently the cutting blade31can be rotated around a horizontal axis32so as to effect the cutting action.

As shown inFIGS. 11 and 12, the hollow tubular section29is moved between a rest position and a gripping position respectively, by means of a linear actuator, such as a cylinder40.

A pipe41connects the hollow tubular section29to a vacuum pump (not shown) thus causing suction from the above-mentioned holes or sectors30for the edge of the film to be blocked.

The rotation movement of the hollow tubular section29for bringing the cutting blade31to act on the film, cutting it, is actuated by a set-square lever42driven by an actuator43, such as a cylinder.

FIG. 13shows a view from below of the gripping unit in a gripping position. In this position, the hollow tubular section29is extracted by means of the cylinder40and brought to a gripping position in which the holes or sectors30are ready for blocking the film.

FIG. 14shows an enlarged detail of the gripping unit ofFIG. 13in which the holes or sectors30, and also the cutting blade31, can be clearly seen.

The functioning of a machine according to the present invention is as follows.

The feeding conveyor12of the products11, consisting for example of a low-friction polypropylene belt, allows the product(s)11to slide during the pushing phase towards the winding group14. The belt is moved with an asynchronous motor controlled by an inverter. The inverter is present for regulating the velocity, acceleration and deceleration in relation to the product to be wound.

The product or products11move on the belt12and are intercepted by a photocell35which is positioned transversally with respect to the belt12. When this photocell35is released as a result of the advancement of the product11, the belt12, if necessary, decelerates, reaching an adequate velocity for the product11and stops when the product11intercepts one of the two capacitive sensors36positioned on an end abutment33. The rotation rates can be programmed by a panel and the advancement rates, which vary from 0-20 mt/min, can be programmed directly on the inverters.

At this point, the product11is ready for being loaded into the winding unit14from the positioning unit13.

The positioning unit13, for example, is composed of a telescopic actuator39with a linear axis which, by means of a pusher34, moves the product11inside the winding unit14above the shelf16. The telescopic actuator39is moved, for example, by a synchronous motor. The run of the actuator is about 1,000 mm, a precision of +/− 5 mm is sufficient in the positioning. The advance rate depends on the product11to be moved, the return is at maximum speed so as to bring the subsequent product11in position in the shortest time possible. The positioning unit13can be completed, depending on the product to be wound, by pneumatic systems for guiding or keeping the product firm during the thrust. The advance rate is 0-40 mt/min.

When the product11is correctly positioned beneath the ring20of the winding unit14, the initial edge of the film is withheld by the vacuum-effect gripping unit18. The initial edge of the film is in fact sucked and withheld by the vacuum created inside the hollow tubular section29.

In this condition, the rotation of the winding ring20is started and the gripping unit is withdrawn allowing a firm winding of the film onto the products11and inFIG. 6, the withdrawn position can be noted of the gripping unit18, which cannot be seen and is dotted.

The ring20then effects various turns so as to firmly fix the film to the product(s)11. During the last of these turns, the gripping unit18re-exits (FIG. 8) and, as the film as passing, it sucks it, withholding it (FIG. 9) acquiring a gripping position (see alsoFIG. 12).

After effecting the gripping, the gripping unit18is commanded to rotate so as to cut the film with the hot blade31which is brought into contact with the film itself by means of the above rotational movement (FIGS. 5, 8 and 10).

The package formed by the wound film is moved forwards by the products11to be packaged which are pushed forwards beneath the winding unit14by the positioning unit13, as already indicated. This pushing movement arranges the packaging on the discharge conveyor belt15which thus packaged, discharges it (FIG. 1).

The cycle is repeated each time.

It should be noted that the machine of the present invention provided with a gripping unit18of this type operates very rapidly and avoids work stoppages without requiring a positioning of the initial edge of the film to be wound.

The cutting, in fact, is effected once the film has been blocked on the gripping unit18and consequently, simultaneously with the generation of a packaged product, the initial edge of the film to be wound is blocked on a subsequent product to be packaged.

It is interesting to note that a new packaging method is also effected in a machine of this type.

A packaging method in extensible film of products11fed individually or in groups, is in fact implemented, by means of a positioning unit13.

A step is first effected for sending a product or plurality of ordered products11in line or transversally to a feeding station.

Said product(s) is then sent by means of a positioning group13above a shelf16positioned beneath a winding unit14.

This is followed by a step for gripping an initial edge of the winding film by means of a vacuum-effect gripping unit18extracted and moved beneath the shelf16carrying the product(s)11.

The subsequent step is to start the winding of the film around the product(s)11followed by a releasing step of the film being wound, withheld by the gripping unit after at least one turn of the film around the products11and withdrawing the gripping unit from beneath the shelf16.

After completing the programmed winding turns of film around the products11, the gripping unit18is brought from a rest position withdrawn from the shelf16, to an extracted position beneath the shelf16carrying the product(s)11.

The suction of the gripping unit18is then actuated, for withholding an edge of the wound film and immediately afterwards rotating said gripping unit18until a cutting blade31integral with the same, cuts a final edge of the film wound around the product(s)11;

This is followed by a step for moving said wound products11to a subsequent discharge belt15and at the same time positioning other products to be wound above the shelf16beneath the winding group14, repeating a previous step.

The subsequent steps already proposed are then repeated.

An important feature of the machine and method of the invention lies in being able to effect a continuous winding of a product or plurality of products to form a packaging without any interruption.

This is possible thanks to the provision of the gripping unit which enables both the tail of the film to be cut and the head of the film to be withheld.

This avoids stoppages of the machine and allows packages of wound products to be rapidly formed and discharged in continuous.

Finally,FIGS. 15 and 16show overall views of a further embodiment of the winding unit arranged in the machine of the present invention and an enlarged detail. In this example, it can be noted how the machine also allows multiple bundles to be wrapped at a time, forming adjacent packagings. The reel holder24in this case carries various reels25of film made of extensible plastic material, in the non-limiting example, three.

Once the winding has been effected with the machine and method already previously described, multiple final packagings of bundles are produced. For this purpose, a gripping unit with multiple sectors is used, which allow various edges of the single reels25to be withheld. The bundles of pre-spaced products11are brought beneath the winding unit14with a special accessory assembled on the pusher34.

FIGS. 17 to 21show a second possible embodiment of the gripping unit alone in an extracted gripping position when positioned beneath the shelf as shown inFIG. 7 or 12of the previous embodiment.

It should be noted that the same reference numbers are used for the same elements, whereas numbers preceded by the index “1” are used for similar elements or having the same function.

The figures therefore show a vacuum-effect gripping unit118also provided with a cutting element suitable for acting on the film. The gripping unit118comprises a hollow section129which carries suction holes or sectors130on its lower surface and facing the film.

A cutting wire131is positioned alongside this hollow section129. The cutting wire is blocked at opposite ends supported on a bar48which provides end pins46. Said pins46, and therefore said bar48, are positioned in supporting extensions47of the structure of the gripping unit118.

At least one actuator143, constrained to the structure of the gripping unit118, causes the rotation of at least one arm45for bringing the cutting wire131in engagement with the film. Also in this case, a further actuator140is provided, which moves the gripping unit118between the rest position concealed inside the structure withdrawn from the shelf16and the gripping position of the extracted film beneath the shelf16.

FIGS. 20 and 21are two enlarged raised front end views of the gripping unit in a gripping position of the film and in a cutting position of the film.

It can be noted in fact that the actuator143causes the rotation of the arm45and consequent movement of the cutting wire131. The cutting wire131is thus brought from a disengaged and distanced position of the film (FIG. 20) to an engaged and cutting position of the film (FIG. 21).

The forms of the structure for providing a machine and a method of the present invention, as also the materials and assembly modes, can naturally differ from those shown for purely illustrative and non-limiting purposes in the drawings.

The protection scope of the present invention is defined by the enclosed claims.