Method and station for hooding products with a tubular covering

Abstract

 A station (10) for hooding with a flexible tubular covering (12) of an article arranged in a hooding zone includes means (17) of peripheral gripping of the covering. The means (17) are movable to seize an end edge of the covering fed to them and have a means (26) of traction and crimping of the wall of the covering starting from said end edge to receive the crimped part in an accumulation zone (30) within the gripping means. The gripping means are reversable to invert the covering which has been crimped thereon and are also movable to slip it onto the article in the hooding zone while gradually releasing the crimped part straight in the accumulation zone.

Description

[0001] This invention relates to a station for hooding of articles with a tubular plastic film covering. In particular this invention is directed at hooding of articles stacked in an orderly manner on pallets.

[0002] The need to wrap products stacked on pallets in an orderly manner with plastic film for protection and containment is known. For example, building materials such as bricks are generally piled on pallets in the form of a parallelepiped which is wrapped in plastic film to keep their form and allow their transport.

[0003] In the known art, there have been proposed various packaging machines and stations allowing rapid performance of packaging by using a tube of relatively elastic plastic material film which is fitted from above on the article to be packaged, usually after elastic expansion of the covering. For example, there have been proposed machines with grips which seize the edge of the covering and pull it onto the product to be packaged while running it from above downward. One problem with this system is that the plastic film opposes not a little resistance to the insertion and because of the friction on the product to be packaged can easily break. To prevent this, it has been proposed to crimp the covering in the grips so that during vertical movement from above downward of the grips along the product the covering is unrolled by the grips onto the product starting from the bottom of the covering toward the edge.

[0004] This system does not always give good results in unrolling of the film, especially with an elastic film tube to be expanded.

[0005] Then there is the problem that the grips, turned upward to receive the edge of the covering, must also have vertical length sufficient to receive the entire crimped covering. They must then descend until reaching with the upper opening the base of the product to be wrapped. This requires foreseeing abundant free space around the base of the product to receive the grips with their handling and the actuators at a height lower than said base. This makes the machine very extended vertically and limits the possibility of inserting automatic product conveyors from and outside the packing station. To seek to remedy at least the second problem, stations with a lift receiving the product from a conveyor at a lower height and lifting it sufficiently to carry the base of the product above the minimum height reached by the upper opening of the grips have been proposed. This introduces a complication in the station, worsens the problem of upward extent of the machine and in any case forces using only particular conveyor systems allowing serving a hoist.

[0006] The general purpose of this invention is to remedy the above-mentioned shortcomings by making available a method and a station for hooding of products, in particular when they are piled on pallets, with a tubular plastic film covering allowing rapid, efficient, flexible hooding with relatively reduced space occupied by the equipment.

[0007] In view of this purpose it was sought to realize in accordance with this invention a station for hooding with a flexible tubular covering of an article arranged in a hooding zone and including means of peripheral seizure of the covering and which are movable for seizing an end edge of the covering fed to them and have means of traction and crimping of the wall of the covering starting from said end edge to receive the crimped part in an accumulation zone within the gripping means with the gripping means being reversable to reverse the covering which has been crimped thereon and also being movable to slip it onto the article in the hooding zone while gradually releasing the crimped part straight in the accumulation zone.

[0008] Again in accordance with the principles of this invention it was sought to realize a method of mechanized hooding with a flexible tubular covering of an article arranged in a hooding zone and including the steps of seizing an end edge of the covering with peripheral gripping means of the covering, crimping the wall of the covering starting from said end edge to insert the crimped part in an accumulation zone in the gripping means, reversal of the gripping means to invert the covering which was crimped thereon and cause the gripping means to run along the article while at the same time unrolling the crimped covering to slip it from the gripping means while progressively releasing it straight on the article to be hooded.

[0009] To clarify the explanation of the innovative principles of this invention and its advantages compared with the prior art there is described below with the aid of the annexed drawings a possible embodiment thereof by way of non-limiting example applying said principles. In the drawings:

FIG 1 shows a diagrammatic side elevation view of a station for film-tube hooding,

FIG 2 shows a diagrammatic top view of part of the station of FIG 1, and

FIGS 3 to 8 show diagrammatically operational steps of the station of FIG 1.

[0010] With reference to the figures, FIG 1 shows diagrammatically a station designated as a whole by reference number 10 for hooding of articles 11 with a tubular plastic-film covering 12. In particular, the article to be packaged can be made up of a pile of objects arranged in an orderly manner on a pallet to form a parallelepiped. The plastic-film tube is of a known relatively elastic type to allow its elastic expansion by traction during packaging of the product and a better adhesion to the walls of the product after release.

[0011] The tubular covering can be made from a continuous tube 13 fed to the machine (for example, in flattened condition) and welded and cut crosswise with known welding and cutting means 14 so as to obtain a hood with the form of a sack and turned downward to hang over the zone of reception of the product to be packaged.

[0012] A hooding unit 15 is realized running vertically on powered command to move between a high position (shown in solid lines in FIG 1) for reception of the covering and a low position (shown in broken lines) for complete hooding of the product. As diagrammatically visible also in FIG 2 the unit 15 has advantageously a frame structure 16 for surrounding the reception zone of the product so as to run along the side walls of the product.

[0013] The unit includes peripheral gripping means 17 of the covering and its crimping starting from the lower edge of the end to accumulate the wall of the covering inside an accumulation zone in said means. Advantageously the gripping means are in the form of four grips which are arranged each near a corner of a rectangle (as seen again in FIG 2).

[0014] As seen in FIG 1 from comparison between the high and low positions of the grips and as explained better below, the gripping means are movable to invert the crimped covering on them and then unroll on the article to be hooded so as to return it to 'straight'. Therefore the grips have the opening turned initially upward to grasp the lower edge of the hanging covering while they have the opening turned downward while they run along the vertical walls of the product being packaged.

[0015] The station can include a horizontal conveyor 23 (for example, a belt-, roller- or similar conveyor) transiting in the hooding zone of the station to bring an article 11 into or out of that zone.

[0016] Advantageously the gripping and crimping means are movable to draw and expand the covering outward before fitting it on the article.

[0017] To this end, the frame 16 includes advantageously powered controlled movement means of the grips to move the grips so as to form on command a rectangle of predetermined dimensions. FIG 1 above shows in solid lines the close position of the grips to receive the edge of the covering as it arrives from the feeder. The grips in removed position after crimping and smoothing of the film are shown in broken lines ready to begin the overturning and descent step. If necessary, means of guidance or positioning grips 28 can be provided opposite the angles of the covering to help a first opening of the tubular covering so as to position the opening thereof correctly on the vertical of the four grips.

[0018] As may be seen in FIG 2, to have coordinated and symmetrical movement of the grips when withdrawing and approaching the frame it is advantageously formed with four guides arranged according to the sides of a rectangle and with a powered symmetrical movement system when withdrawing from and approaching for each pair of parallel guides. For each pair of guides the power system can advantageously include a screw-nutscrew transmission 18, 19 moved by a corresponding motor 20, 21. At each crossing between two right-angle guides there is an appropriate carriage 22 for support of a grip 17.

[0019] As seen diagrammatically in FIG 2, the grips are advantageously oriented in the plane so as to grip each covering on a different side of the rectangle near a different corner. For ease of description and drawing, in the side views the grips are shown anyway simply as a pair of specularly facing grips.

[0020] The horizontal movement of the grips allows expanding the covering by stretching the elastic film so as to take it to a larger size than that of the product to be packaged and allow it to be easily slipped in. The actual extent of the movement will depend on the dimensions of the product to be packaged. The machine can thus receive and handle articles of different sizes.

[0021] FIG 3 shows in greater detail two grips 17 in close position. Each openable grip is advantageously equipped with a fixed jaw 24 and a jaw 25 movable on command in opening and closing with an appropriate actuator (not shown). The grip also includes powered means for pulling the covering towards the inside of the grip and crimping it between the jaws in an accumulation zone 30 realized sufficiently long. These powered means include advantageously a powered roller 26 near the grasping end of the grip on the fixed jaw. An idling counter-roller 27 is correspondingly on the end of the movable jaw.

[0022] FIG 3 shows the first step of a hooding cycle with the grips open and close together and the covering 12 not yet expanded and held by positioning grips 28 to slip the opening into the grips. In the following step, the grips close and the powered means crimp the covering in the grip accumulation zone as shown in FIG 4. After crimping, the grips are commanded to rotate oppositely one to the other around the axis 29 to turn over downward so as to invert the covering (FIGS 5 and 6). During or before this step the grips can be moved appropriately outward to avoid mutual interference. The covering is kept gripped while holding the powered rollers stopped.

[0023] At the end of the rotation the covering sack keeps the weld turned upward but the grips are above the sack. In addition, the powered wrapping wheel moves to the inside of the perimeter of the sack and the pressing roller outside.

[0024] After reversal by 180°, the four grips are commanded to withdraw symmetrically (FIG 6) to stretch uniformly the four sides of the tubular covering to the size sufficient to fit it on the product arrived in the hooding zone. The powered roller inside facilitates the following operation of stretching by keeping the film firmly blocked.

[0025] After reaching the correct expansion, the hooding unit begins descent on the package by progressively unrolling the crimped covering between the grips (FIG 7).

[0026] As seen in FIG 8, in the final part of the hooding the inclination of the grip units can be changed so as to facilitate expulsion of the film.

[0027] At this point the hooding is finished, the hooding unit 15 can rise again and the packed product can be evacuated from the station with the contracted film blocking it firmly.

[0028] To optimise times, during the packaging steps a new covering hanging from the supply unit can be prepared.

[0029] It is now clear that the preset purposes have been achieved by making available a hooding method which by first reversing the covering and then unrolling it to bring it back to straight allows rapid and efficient hooding of products with a tubular plastic film covering. It is thus possible to realize a fast and flexible station. With the resulting descent forward of the grips of the hooding unit, the unrolling of the film on the package is more uniform and the grips can reach to the base of the package with no need of providing space for them below the base level of the package. This allows reduced height of the station and using a conveyor with no need of vertical hoists.

[0030] In addition, reversal with subsequent unrolling forward brings the film back into its position with the outer face still outward on the package. This is for example indispensable with printed coverings.

[0031] Naturally the above description of an embodiment applying the innovative principles of this invention is given by way of non-limiting example of said principles within the scope of the exclusive right claimed here. For example, the positioning means and the exact structure of the grips can be different depending on specific requirements. The grips can even be arranged directly on the diagonals of the rectangle.

Claims

1. Station (10) for hooding with a flexible tubular covering (12) of an article arranged in a hooding zone and including means (17) of peripheral gripping of the covering which are movable for grasping an end edge of the covering fed to them and have means (26) for traction and crimping of the wall of the covering starting from said end edge to receive the crimped part in an accumulation zone (30) within the gripping means with the gripping means being reversible to invert the covering,which has been crimped thereon and also being movable to slip it onto the article in the hooding zone while gradually releasing the crimped part straight in the accumulation zone.

2. Station in accordance with claim 1 characterized in that the gripping means include mutually movable grips (17) with jaws (24, 25) for seizing the edge of the covering and having powered means (26, 27) for drawing the seized covering toward the inside of the grip and into the accumulation zone (30).

3. Station in accordance with claim 2 characterized in that the powered means include a powered roller (26) near one seizing end of the grip jaws.

4. Station in accordance with claim 2 characterized in that the grips (17) are rotatable between a first position oriented upward and a second position oriented downward to receive in the first position the edge of the opening of the covering dropped from above and to reverse the covering by moving toward the second position once crimped in the accumulation zone.

5. Station in accordance with claim 2 characterized in that the grips (17) are supported in a hooding unit (15) which defines a frame which moves vertically around a hooding zone intended to receive the product to be hooded.

6. Station in accordance with claim 2 characterized in that the grips are four in number with each supported near a corner of a rectangle.

7. Station in accordance with claim 2 characterized in that the grips (17) are supported by grip handling means (16, 18, 19, 20, 21, 22) which can withdraw them or draw them near mutually on command in directions transversal to the extension of the covering.

8. Station in accordance with claim 7 characterized in that the grips handling means include four guides (16) arranged in accordance with the sides of a rectangle and with a powered system (18, 19, 20, 21) for symmetrical handling in withdrawing and approaching for each pair of parallel guides (16) with grip support carriages (22) being arranged at each crossing of the guides (16) at a right angle to have a coordinated and symmetrical movement of the grips in withdrawing from and approaching the operation of the powered system.

9. Station in accordance with claim 6 characterized in that the grips (17) are oriented in a plane so as to each seize the covering on a different side of the rectangle near a different corner.

10. Station in accordance with claim 1 characterized in that it includes a conveyor (23) which transits in the hooding zone to take an article into and out of said zone.

11. Station in accordance with claim 1 characterized in that it includes means of feeding the covering with opening turned downward above the hooding zone.

12. Station in accordance with claim 11 characterized in that the means of feeding the covering include means (14) of cutting and welding crosswise a continuous plastic film tube to form from it the covering in sack form.

13. Method of mechanized hooding with a flexible tubular covering of an article arranged in a hooding zone and including the steps of seizing an end edge of the covering with means of peripheral gripping of the covering, crimping the wall of the covering starting from said end edge to insert the crimped part into an accumulation zone within the gripping means, reversing the gripping means to invert the covering which has been crimped on them, cause running of the gripping means along the unrolling article simultaneously with the crimped covering to slip it off of the gripping means while releasing it gradually straight onto the article to be hooded.

14. Method in accordance with claim 13 in which between the step of seizing the edge of the covering and the step of unrolling the crimped covering there is another step of drawing and expanding the covering transversely toward the outside to take it from a transversal feeding size to a larger transversal size larger than, that of the article to be hooded.

Drawing