Machine and method for stacking crates for containing products

Technical field

The present invention relates to a machine and a method for stacking crates for containing products. In the technical field, such crates are also called cases. They can have a reticular structure and are open at the top to enable them to be stacked. With stacking, a part of the bottom of the overlying crate is inserted inside the underlying crate.

The machine and the method according to the present invention enable various layers of crates containing products, typically foodstuffs, which have to be shipped, to be stacked on pallets.

State of the Art

There are known systems enabling the stacking of crates which implement the following steps:

-lifting the column of already stacked crates;

-positioning the crate yet to be stacked below the column of crates;

-resting the column of crates on the crate inserted below.

A drawback of such a modus operandi is tied to the fact that the crates can sometimes be deformed or broken, for example as a result of impacts.

In fact, they are normally made of plastic material and are reused several times; moreover, the need to optimise production costs has made them increasingly lightweight.

If the crates are deformed, correct stacking may be precluded. In fact, one side of the underlying crate might not extend in a rectilinear manner, but rather protrude inwards. As a consequence, the underlying crate will prevent the insertion therewithin of the overlying crate. In order to obviate this drawback, the crates fed to the stacking machine are visually inspected by persons who will remove the defective crates if necessary. This solution implies a major cost. Moreover, human error cannot be ruled out, as the operation is highly repetitive.

Object of the invention The object of the present invention is to solve the above-mentioned problems.

In particular, the object of the present invention is to propose a machine and a method for stacking crates for containing products which enable optimal functioning, even when reusing potentially damaged crates.

The stated technical task and the specified objects are substantially reached by a machine and a method for stacking crates for containing products comprising the technical features disclosed in one or more of the appended claims.

Brief description of the drawings

Additional features and advantages of the present invention will become more apparent from the approximate, and hence non-limiting, description of a machine for stacking crates for containing products illustrated in the appended drawings, in which:

-figure 1 shows a perspective view of a machine according to the present invention;

-figures 2, 3 and 4 show enlargements of figure 1 ;

-figure 5 shows a further perspective view of a machine according to the present invention;

-figures 6 and 8 show two views that illustrate two steps of a method according to the present invention;

-figure 7 shows an enlargement of figure 6.

Detailed description of preferred embodiments of the invention

In the appended figures, the reference number 1 indicates a machine for stacking crates for containing products. The crates are typically crates of equal size that serve as containers for products of various types, above all foodstuffs.

In a preferred embodiment, the crates are loaded on a pallet that facilitates the transport thereof. The machine 1 can comprise a pallet conveyor (for example a belt or roller conveyor). The machine 1 can further comprise a means for stopping the advancement of the pallet along the conveyor. For example, the stopping means can comprise an abutment that intercepts the pallets moving along the conveyor.

The machine 1 comprises stacking means 6 for stacking the crates in superposed layers. This takes place in a stacking zone 55 (see figure 6). Typically, the stacking means 6 comprise a robot 60 for stacking the crates. The stacking means 6 will initially rest a first layer of crates on the pallet and subsequently proceed to stack the other layers of crates on top of the first pallet. The presence of retaining means 10 for retaining a layer in said stacking zone 55 contributes to this (see, for example, figure 2). The retaining means 10 comprise abutting means 8 which externally delimit the stacking zone 55 at least partly (but preferably they surround it completely).

Conveniently, the machine 1 comprises compensating means 2 for compensating a possible lateral crushing of the crates. This is to avoid the risk that a crate cannot be inserted in the top opening of the underlying crate.

The compensating means 2 comprise traction means 3 for the traction of at least a side of a crate (see for example figure 2).

The abutting means 8 stop a deformation of one or more crates induced by said traction means 3. This avoids outward bulging of the crate which could deform other zones of the crate, thus compromising the possibility of stacking it.

The traction means 3 comprise in particular a means for spreading apart two opposite sides of the perimeter of the first layer of crates by a predetermined distance.

In the course of the present description, the expression "set of crates" shall also include the extreme case in which the set consists of a single crate. In the preferred embodiment, the set of crates consists of four crates. They are arranged according to a 2x2 matrix scheme (2 rows and 2 columns).

The stacking means 6 operate downstream of said compensating means 2 for compensating a possible lateral crushing of the crates. In fact, after having compensated for the deformations, it will be possible to carry out a correct stacking with maximum reliability.

The traction means 3 comprise a plurality of actuators 30, preferably of a fluid-dynamic type. They are advantageously arranged in a first and a second row which are reciprocally parallel. The rows of actuators 30 take hold of edges lying on two opposite sides of the perimeter, as per a plan view, of a layer of crates. If the crates are rectangular, the actuators 30 perform their action on the long side of the perimeter. Advantageously, the actuators 30 comprise a lower portion 31 for gripping the crates (see for example figure 3). The actuators 30 comprise a lead-in edge 32 situated in an upper portion which facilitates the insertion from above of a layer of new crates. The lead-in edge 32 is exemplified by the flare illustrated, for example, in figure 3.

The compensating means 2 comprise reciprocal blocking means 4 for blocking two flanked sides of two adjacent crates (see figure 4). The reciprocal blocking means 4 comprise a first and a second arm 41 , 42 which define, interposed between them, a seating 40 for housing a portion of two flanked sides of two adjacent crates. Figure 6 shows the blocking means 4 operatively engaged on the crates.

The reciprocal blocking means 4 are tiltable about a horizontal axis between an operating position in which the first and second arms 41 , 42 are reciprocally neared and engage two adjacent crates (like for example in figure 6) and a rest position in which they are reciprocally distanced and disengaged from the crates. The first and the second arm 41 , 42, besides tilting about said horizontal axis, can be axially neared and distanced in order to block/disengage the two flanked crates. Conveniently, in the operating position the first and second arms 41 , 42 extend substantially horizontally; in the rest position they can extend vertically (not illustrated). During tilting, the first and second arms 41 , 42 are able to disengage from the crates and move without being hindered by the walls of the crates. Conveniently, the abutting means 8 comprise four nearable flanks 51 , 52, 53, 54. They come near one another, while remaining reciprocally at a right angle, to surround a stacking zone 55 of the crates. Therefore, the four flanks 51 , 52, 53, 54 define a quadrilateral with orthogonal sides. The abutting means 8 are compacting means (if the layer of crates consists of a number of crates). The abutting means 8 are also means for self- centring the crate or the crates in a predetermined unloading zone of the stacking means 6. This enables a correction of the deformations and enables the subsequent reception of the new layer of crates from above. The machine 1 comprises a single electric motor 57 for activating the nearable flanks. In this regard, the machine 1 comprises four rotating assemblies 56 activated by the electric motor 57 (see figure 6). The four rotating assemblies 56 extend along corresponding sides of a quadrilateral with orthogonal sides. The machine 1 further comprises means for converting the rotational motion of said rotating assemblies into means for the translation of said flanks 51 , 52, 53, 54.

Conveniently, gear mechanisms enable the transfer of motion from one of said flanks 51 , 52, 53, 54 to another.

At least one of said flanks, but preferably each of said four flanks 51 , 52, 53, 54 comprises (see for example figure 3):

- a lateral panel 50;

- an anti-surmounting partition wall 500 which prevents two flanked crates from surmounting one another.

In the operating position of the reciprocal blocking means 4, at least one of the partition walls 500 can be interposed between the first and second reciprocal blocking arms 41 , 42.

The partition wall 500 extends from said panel 50 and protrudes towards the inside of the stacking zone 55. The partition wall 500 comprises a vertical plate which is interrupted in a lower portion of said panel 50. This allows the panels 50 also to perform a function of self-centring the pallet intended to support the crates. The partition wall 500 extends at half the length of the panel 50.

In the preferred embodiment, the four flanks 51 , 52, 53, 54 comprise:

- a first and a third flank 51 , 53, reciprocally opposite;

- a second and a fourth flank 52, 54, reciprocally opposite.

The reciprocal blocking means 4 are positioned at least along the first and third flanks 51 , 53. Conveniently, above the first and third flanks 51 , 53 there are rollers 7 which facilitate the sliding of the crates that are introduced from above (see for example figure 4). Advantageously, the rollers 7 can rotate, preferably idly, about corresponding horizontal axes. The traction means 3 are positioned along the second and fourth flanks 52, 54 (see figure 2).

The present invention also relates to a method for stacking crates containing products. Conveniently, said method is implemented by a machine 1 having one or more of the previously described features.

The method comprises the following steps:

- defining a first layer 91 with a first set of crates 9 (see figure 6);

-positioning the lateral abutting means 8 of the first layer 91 in such a way that they self-centre and retain the first layer in a stacking zone 55 (in figure 6 the abutting means 8 are partly hidden by the crates and are better visible in figure 2, where the crates have been omitted);

- stacking a second set of crates 9 on the first set of crates so as to form a second layer 92 (see figure 8).

Typically the first set of crates 9 comprises a plurality of crates 9, preferably four, but it could also comprise even only one. A similar thing may be repeated for the second set of crates.

The crates 9 comprise a structure that is advantageously reticular. Advantageously, it is defined by the combination of longitudinal strips that intersect one another.

The method comprises the steps of compensating for any deformations of the crates 9 in the first set. This takes place before the step of stacking a second set of crates on top of it. Since the crates 9 are open at the top, the step of stacking the crates 9 comprises introducing the bottom 901 of the second set of crates 9 inside the top opening 902 of the crates 9 of the first set.

The step of compensating for any deformations of the crates 9 of the first set comprises the sub-step of pulling at least a side (the upper part of a lateral wall) of a crate of the first set until it is abutted and stopped by the abutting means 8.

In the preferred embodiment, the step of compensating for any deformations of the crates of the first set comprises the sub-step of pulling two opposite sides 903, 904 of the overall perimeter, as defined in a plan view by the first set of crates 9, along opposite directions. In the case of rectangular crates 9, this envisages that the longer sides of the crates 9 are pulled transversely to their main direction of extension (with reference to figure 2, see the arrows indicated by the reference number 300). In particular, the step of pulling the two opposite sides 903, 904 of the perimeter of the first set of crates 9 comprises taking hold of the two opposite sides 903, 904 and spreading them apart. This involves straightening the two opposite sides 903, 904, constraining them between: -the lateral abutting means 8 (which, in the preferred embodiment, is a quadrilateral enclosure), which prevents bulging towards the outside of the crates 9 of the first set; and

-actuators 30 (gripping means) which pull the two opposite sides 903, 904 towards the quadrilateral enclosure.

The actuators 30 are activated fluid-dynamically. Advantageously, they are supported by the quadrilateral enclosure, and comprise a fluid-dynamically activated element that is movable relative to the quadrilateral enclosure. The fluid-dynamically activated element can:

-be raised and lowered relative to the quadrilateral enclosure in order to be partly introduced into one of the crates 9 of the first set;

-move nearer to and away from the quadrilateral enclosure in order to block or release the crate 9. Conveniently, the step of stacking the second set of crates 9 on the first set of crates 9 comprises partly introducing a bottom 901 of the second set of crates 9 into the upper opening 902 of the first set of crates 9 (see figure 7). This is facilitated by the presence of rollers 7 rotatable about a substantially horizontal rotation axis and positioned above the quadrilateral enclosure (shown in figure 4). Furthermore, it is facilitated by the presence of an inclined lead-in edge 32 formed in the upper part of the actuators 30 (see figure 3).

The step of compensating for any deformations of the crates 9 also comprises the sub-step of reciprocally retaining at least a portion of two adjacent sides 905, 906 of two flanked crates 9 of the first set. In particular, this is achieved by inserting said portion of the adjacent sides 905, 906 in a seating 40 interposed between a flanked first 41 and a second arm 42. The first and second arms 41 , 42 are parallel plates.

After the step of stacking a second set of crates 9 on the first set of crates 9 (figure 8), the method comprises tilting the first and second arms 41 , 42 upward, thus disengaging said portion of the adjacent sides 905, 906, and extracting the first and second arms 41 , 42 from the crates of the first and second sets. The step of tilting the first and second arms 41 , 42 upward comprises rotating the first and second arms 41 , 42 about a horizontal axis. During this rotation, the first and second arms 41 , 42 move inside slots interposed between frameworks defining the crates 9 of the first and second sets.

The step of positioning the first set of crates defining the first layer 91 comprises the step of placing the first layer 91 on a pallet. Before the step of compensating for any deformations, the method comprises the step of positioning the pallet in a predetermined position and compacting the first set of crates 9 placed on the pallet. The steps of positioning the pallet and compacting the first set of crates 9 comprise the steps of nearing, while keeping them at a right angle, four flanks 51 , 52, 53, 54, in such a way as to block said first set of crates 9 between them. Furthermore, the step of compacting the first set of crates 9 also brings about the centring of the pallet relative to a predetermined zone 55 in which the positioning of the first set of crates is provided for. In this zone, it is also envisaged that stacking means 6 will position the second layer 92 of crates from above. It is thus important that there be a precise positioning of the pallet and of the first set of crates 9 relative to a zone in which the positioning means will release the second layer 92 of crates 9. After the step of stacking a second set of crates 9 on the first set 91 of crates so as to form a second layer 92, the method comprises the step of raising a platform comprising said quadrilateral enclosure and said gripping means 30 so as to straighten any deformations of the second layer 92 of crates in order to prepare them to receive the partial introduction of a third layer of crates positioned above. By proceeding iteratively in the above-described manner, it is possible to stack further layers of crates on top of the third layer. Care will always be taken to compact the set of crates that is about to receive the new layer of crates, and if necessary to spread apart any deformed edges of the crate that protrude towards the inside of the crate.

With reference to the embodiment of the appended figures, the machine and method according to the invention, in the preferred embodiment, comprise:

-advancing a pallet to the stacking zone 55;

-positioning a first layer of crates on top of the pallet by means of the robot;

-compacting the crates (four in the specific case) by compressing them between four flanks 51 , 52, 53, 54 that are reciprocally neared, at a right angle, up to a predetermined distance that takes account of the undeformed dimensions of the crates and the presence of the partition walls 500 (figure 6);

-spreading apart the opposite sides of the layer of crates until bringing them into contact with two opposing flanks used to compact the crates (via the traction means 3);

-retaining the flanked sides of two adjacent crates via the blocking means 4;

-positioning, via the robot, an additional layer on top of the underlying layer (figure 8).

The invention thus conceived makes it possible to achieve multiple advantages.

First of all, it enables crates for containing products to be stacked with the maximum speed and reliability, also in the event that use is made of crates already employed previously. Reused crates can in fact exhibit deformations which under standard conditions would be an obstacle to the introduction of a layer of crates into an underlying layer of crates.

The present invention further makes it possible to assure the correct insertion of crates since it enables the deformations of the crates to be correctly compensated for by pulling the deformed flanks of the crates until they are brought into contact with a predetermined enclosure defined by the abutting means 8 (which thus enable the crates to be repositioned in an initial undeformed configuration).

The invention thus conceived is susceptible to numerous modifications and variants, all of which falling within the scope of the inventive concept characterizing the invention. Moreover, all details may be replaced with other technically equivalent elements. All the materials used, as well as the dimensions, may in practice be of any type, according to needs.