IT202300009684A1 - PLASTIC PALLET AND RELATED PRODUCTION SYSTEM - Google Patents

Description

Description of the invention entitled:

?PLASTIC PALLET AND RELATED PRODUCTION SYSTEM?

Description

Field of technique

The invention relates to the field of logistics and specifically to pallets used for the transport and storage of goods. Even more specifically, the invention is designed to provide a plastic pallet and the related production system that adopts various printing technologies and control devices capable of ensuring temporal sequencing in production.

Known art

A pallet is a flat structure on which goods are placed. A pallet is the structural foundation of a unit of load that allows for movement and storage by means of tools such as forklifts, pallet trucks, and the like. Since its invention in the twentieth century, the use of the pallet has gradually replaced older storage systems, such as wooden boxes and barrels. Although the most commonly used material for pallets remains wood, there are also pallets made of plastic, metal, or recycled material.

It can be said that the pallet has now become an integral part of the logistics chain: even companies that manage bulky or non-standard format goods, and therefore are unable to use standard format pallets, procure pallets with specific characteristics (both in size and material) to best complete the packaging of their materials. Today you can find pallets of many types, from super light ones for loading plastic objects to more robust ones for loading metals (in ingots for example), from those half the size of the standard for small shipments to longer ones for loading materials in bars (furniture profiles for example). An added value of the palletization of goods is also that, after having wrapped the contents with transparent plastic films (now also in common use), you can obtain further protection of the materials against damage caused by the movement of means of transport and by bad weather, as well as a greater guarantee against theft. Among the most popular pallets are the 100% made in Italy pallets. The most widespread ones today are those made of plastic materials. The speed of their production, their great workability, their recyclability and their mechanical characteristics make them the ideal elements for the transport of materials of any kind.

There are many examples of patents that have dealt with proposing solutions to problems of various kinds connected to the production of plastic pallets.

An example is the subject of patent application WO2006094121A2 by . The invention relates to a plastic pallet for use with forklifts and which meets the requirements associated with food handling. The pallet has a thermoplastic top consisting of two sheets which are partially spaced apart by rigid foam. There are steel reinforcing members which run in an X-configuration within the foam. The plastic sheets each have a plurality of truncated cone-shaped depressions which provide passages for water and air. The plastic sheets are welded together at the depressions and their outer edges.

Another example is the subject of U.S. Patent Application US6,250,234B1. The invention relates to a method of reinforcing a plastic pallet having a plurality of relatively weak structural portions each comprising a sheet metal portion with a plurality of vertical ribs extending therefrom. The method involves securing a plurality of sheet metal strips to the vertical ribs in the plurality of relatively weak structural portions, respectively, to form a plurality of substantially rectangular hollow vertical cross-sections along the length of the weak structural portions to enhance the rigidity thereof.

Another example is the subject of the utility model ITMI20000640U1. The invention refers to a pallet made in such a way as to improve its visibility and the identification of the insertion points of the lifting devices. The invention also provides for the creation of a pallet in modular shapes and with plastic materials of various types.

The inventions reported so far for purely illustrative and non-exhaustive purposes are representative of the inventive-technological framework available to date and present technical problems related to monitoring the assembly of the correct pieces of a pallet during the production phase, to the creation of a weld between two components without removing RFID tags (or in any case without using RFID tags resistant to high temperatures and therefore more expensive), to knowing at any moment in real time the position of the pallet components along the production lines in order to always have control over the assembly of the correct components and to the times and difficulties in mounting deformation sensors on the pallets themselves.

The present invention describes a system for the production of plastic pallets made by joining two half-shells using vibrational, ultrasonic or hot blade welding techniques which provides a solution to the above-mentioned technical problems.

Description of the invention

According to the present invention, a plastic pallet and the related production system are created.

The production system includes a gas injection printing apparatus, a vibration welding machine, a hot blade welding machine and allows the simultaneous production of pallets with different welding methods and geometries, through the welding of two or more components, each including an RFID tag. The production system is composed of other fundamental parts which are: - a database in which the identification code of each RFID tag is saved and the information on the geometry, material and production date of the relative component. The database contains, for the RFID tag of a first component of a pallet, the identification codes of the RFID tags relating to the other components to be welded to said first component. In this way, even if there were to be an exchange of components along the production line, the welding machines would not weld them together as an erroneous association between two RFID tags would be previously detected which, based on what is reported in the database, should not be associated;

- RFID readers mounted on said vibration welder and said hot blade welder, capable of reading the RFID tags of the components to be welded together;

- a control device for managing the printing cycles of said gas injection printing device and for managing the transport of the printed components to said vibration welder and/or said hot plate welder and for managing the operation of these machines. The control device receives data from the RFID readers to verify the correct pairing between two components; when the RFID tags read by the RFID readers identify an incorrect correspondence between two or more components (i.e. they do not match the associations between RFID tags present in the database), said vibration welder and/or said hot plate welder are stopped by said control device which also sends a signal via an alert device. Finally, the control device has a user interface that can be consulted via a portable device such as a smartphone, a tablet and/or similar (when the device is equipped with a wireless communication unit) and/or via one or more displays included in the production system;

- this warning device sends reports of malfunctions or incorrect correspondences between two or more components through warning lights, audio systems, notifications via email, SMS and/or similar.

In some embodiments, the system comprises a robotic handling apparatus for said components and/or said pallets to fully automate the production process of said pallets. In these embodiments, the robotic handling apparatus comprises conveyor belts, robotic arms, robots that move on tracks and/or other programmable robotic elements to allow the production of the pallets in an automatic manner which will not be described herein as they are considered part of the art known to a professional skilled in the art.

The advantages offered by the present invention are evident in light of the description set forth thus far and will be even clearer thanks to the attached figures and the relative detailed description.

Description of the figures

The invention will be described below in at least one preferred embodiment for explanatory and non-limiting purposes with the aid of the attached figures, in which:

- FIGURE 1 shows a general view of the 100 plastic pallet production system;

- FIGURE 2 shows an exploded view of a plastic pallet 10 produced with said production system 100.

Detailed description of the invention

The present invention describes a system for producing plastic pallets 10 which includes a gas injection molding apparatus 20, a vibration welder 30, and a hot plate welder 40. The gas injection molding apparatus 20 is used to produce various components 11 of the pallets 10.

Gas injection molding is the process of printing a plastic component by which a molten mass of material (plastic) is injected into a mold, and gas (preferably nitrogen) is subsequently injected into the molten mass. The process begins with the injection of a quantity of plastic material in percentages preferably within the range of 60% to 98% of the volume of the mold cavity. Subsequently, with the injection of gas into the molten mass, a bubble is formed that remains connected to the gas injection point, the pressure of which pushes the plastic material against the internal walls of the mold until it completely fills the mold cavity. The pressure on the gas is maintained until the part's extraction temperature is reached.

Vibration welding is a welding process between plastic components that involves the use of vibration. The vibration of the parts produces friction that raises the temperature of the surfaces in contact until the materials melt together (weld). The vibration welding method does not require an external heat supply but this comes from the dissipation of the energy produced by friction. The increase in local temperature necessary for the process is obtained with rubbing that melts the appropriately prepared edges of the two pieces to be welded. These, in the cooling phase under pressure, remain welded. A pushing pressure is applied to the piece subjected to movement in order to keep the parts to be joined in contact during the welding process.

Hot plate welding is the process in which a plate or blade is heated, thanks to the use of multiple resistors. Once brought to the correct temperature, the blade is placed between the two pieces to be welded. The hot plate is left in contact with the two pieces for the time necessary to melt the material of the pieces to be welded, after which the blade is removed and the two pieces are joined together, which, being also at very high temperatures, are welded in the contact areas.

The production system 100, according to the present invention, allows to produce plastic pallets 10 by welding two or more components 11 each of which includes an RFID tag 101. Having an RFID tag 101 on each of the components 11 of a pallet 10 to be welded allows to know from the molding of the individual components 11 which of them will be welded together. This allows to have control during the entire production line and to avoid welding errors due to the incorrect coupling of two components 11 that were not intended to be welded together. The particular welding machinery that is used in the production system 100 also allows to maintain the RFID tags 101 even during welding since the high welding temperatures remain, both with said vibration welder 30 and with said hot blade welder 40, localized to the contact areas, and do not reach the point of damage to the RFID tags 101 which are purposely placed far away from the welding areas.

The production system 100 of the present invention is therefore able to overcome the technical problem of monitoring the assembly of the correct pieces during the production phase and the technical problem related to the creation of a weld between two components without removing RFID tags 101 (or in any case without using RFID tags that are resistant to high temperatures and therefore more expensive).

In some embodiments of the present invention, an additional RFID tag 101 is applied to the welded pallet 10 so as to be identifiable to the finished product. In other embodiments, reading even a single RFID tag 101 of a single component 11 of the already welded pallet 10 allows the identification of the finished product.

The present invention will now be illustrated purely by way of example but not in a limiting or binding manner, using the figures which illustrate some embodiments relating to the present inventive concept.

With reference to FIG. 1, a general view of said production system100 according to the present invention is shown. In FIG. 1, as in the following description, the embodiment of the present invention considered to be the best to date is illustrated.

The said production system 100 allows for the simultaneous production of 10 plastic pallets that have different geometries and different welding methods (customizable according to the use needs of the pallets 10 themselves). The production system 100, in addition to the apparatus and machinery mentioned above, includes:

- a database 110 in which the identification code of each RFID tag 101 is saved, as well as information which, by way of example and not limitation, may concern the geometry, material and production date of the relevant component 11. In the database 110 the RFID tags 101 are associated so that the RFID tag 101 relating to a component 11 is associated with all the other RFID tags 101 of other components 11 which must be welded together to create the same pallet 10;

- RFID readers 120 mounted in correspondence with said vibration welder 30 and said hot blade welder 40, suitable for reading the RFID tags 101 of the components 11 to be welded together;

- a control apparatus 130 for managing the printing cycles (in terms of frequency, time, and type of components 11 to be printed) of said gas injection printing apparatus 20 and for managing the transport (in terms of transport speed and in terms of direction, i.e. whether to direct them towards one machine or the other) of the printed components 11 towards said vibration welder 30 and/or said hot blade welder 40. Said control apparatus 130 receives data from the RFID readers 120 to verify the correct coupling between two components 11 and when the RFID tags 101 read by the RFID readers 120 identify an incorrect correspondence between two or more components 11, it sends a message to the printer 130. components 11 (i.e. they identify, by way of example and not in a limiting or binding way, the presence at said vibration welder 30 and/or said hot blade welder 40 of a first component 11 relating to a first pallet 10 and a second component 11 not relating to said first pallet 10) said vibration welder 30 and/or said hot blade welder 40 are stopped by said control apparatus 130 which also sends a signal via an alert apparatus 140. Said control apparatus 130 has a user interface 131 which can be consulted via a portable device such as a smartphone, a tablet (shown in FIG. 1) and/or the like;

- said warning device 140 which sends signals of malfunctions or incorrect correspondences between two or more components 11 through warning lights, audio systems, notifications via email, SMS and/or similar;

- a sensor assembly station 150 in which one or more deformation sensors 151 are mounted on said pallet 10; said deformation sensors 151 are designed to measure the bending of the component 11 in direct contact with the goods 1 (not shown in the Figure) placed on the pallet 10. Goods 1 being understood to mean any type of object that must be placed and/or transported with said pallet 10;

- a robotic handling apparatus 160 for said components 11 and/or said pallets 10 to completely automate the production process of said pallets 10. Said robotic handling apparatus 160 comprises means for automatic handling which are conveyor belts and programmable robotic arms to allow the production of the pallets 10 automatically. Said robotic handling apparatus 160 comprises RFID readers 120 arranged on the means for automatic handling of said components 11 and/or said pallets 10 so that, when the RFID readers 120 mounted in correspondence with said vibration welder 30 and/or said hot blade welder 40 detect an incorrect correspondence between two or more components 11, said control apparatus 130 shows the user, on the user interface 131, the real-time position of the correct components 11, on the robotic handling apparatus 160, whose RFID tag 101 has been read by one or more RFID readers 120 arranged on the means for automatic handling.

The synergy between the technologies included in the production system 100 allows said strain sensor 151 to be installed on the components 11 before their welding. This allows to avoid a considerable waste of time related to the installation of the strain sensor 151 on the finished pallet 10 and therefore subsequently to the welding phase of the components 11 since calibration operations would be necessary and the insertion of the sensor in the innermost parts of the pallet 10 would be difficult.

This last feature overcomes the technical problem of needing to know, on large robotic handling apparatus 160 (where there are a multitude of means for automatic handling and a multitude of gas injection printing apparatus 20, vibration welders 30 and hot plate welders 40), the exact position of a component 11 that is being searched for. This feature also provides an accurate indication of the position (along the robotic handling apparatus 160) of the correct components 11 to be welded together, when the RFID readers 120 located at said vibration welder 30 and hot plate welder 40 report incorrect matches. That is, having a first component 11 that must be welded with a second component 11 both relating to a first pallet 10, if the presence of the first component 11 is detected at said vibration welder 30 or said hot blade welder 40 together with a component 11 of a second pallet 10, the control apparatus 130 sends a signal of incorrect correspondence through the alert apparatus 140 and on said user interface 131 also showing the positions of the second component 11 relating to the first pallet 10, and of the other components 11 relating to the second pallet 10 on a graphic that indicates them along the robotic handling apparatus 160.

The production system 100 shown in FIG. 1 also allows the production of plastic pallets 10 even entirely composed of recycled plastic, but also pallets with metal and other reinforcing elements.

In other embodiments of the present invention (not shown in FIG. 1), said user interface 131 is accessible via one or more displays included in the production system 100.

With reference to FIG. 2, two bottom views of a plastic pallet 10 produced with said production system 100 are shown. Said pallet 10 will be described with reference to FIGS. 1 and 2.

In FIG. 2A, an exploded view from below of said pallet 10 is shown, in which it is observed that it comprises numerous components 11 and that each of them has an RFID tag 101. In FIG. 2A, two components of a strain sensor 151 are also observed, which are a first upper part 157 (mounted on the upper component 11 in said sensor assembly station 150) and a second lower part 158 (mounted on the lower component 11, mounted in said sensor assembly station 150). The second lower part 158 is large enough to fit inside the first upper part 157 which is slightly wider. The sliding of the first upper part 157 on the second lower part 158 follows the lowering of the upper component 11 (as will be explained later in relation to FIG. 3). The first upper part 157 and the second lower part 158 have a height such that they cannot be welded in said vibration welder 30 and said hot blade welder 40.

In FIG. 2B a bottom view of said pallet 10 at the end of production is shown, it can be observed how said pallet 10 has undercuts 12 (undercuts meaning protrusions of one or more components that are located at the bottom of the pallet 10, in contact with the ground or with another support) being made by welding two or more components 11 using said vibration welder 30 and/or said hot blade welder 40. Said undercuts 12 are such as to increase the contact surface with the ground (increase it with respect to the sole shape of the components 11 welded above) allowing a better distribution of the loads since, in this way, the surface pressure on the support elements is distributed over a larger area reducing the average tension and therefore the deformations and the risk of punching. The pallet 10 of FIG. 2B has the second lower part 158 inserted inside the first upper part 157 thus creating a strain sensor 151.

With reference to FIG. 3, two enlarged views of said strain sensor 151 mounted on said plastic pallet 10 made with said production system 100 are shown. Said strain sensor 151 will be described with reference to FIGS. 1, 2 and 3.

The said strain sensor 151 works analogically without the need for power supply (from electricity, battery and/or other). In both images shown in FIGS. 3A and 3B, the dashed elements are hidden inside a cover body of the strain sensor 151 which, by way of example and not limitation, can be made of rubber, plastic or made of different materials in order to accommodate the deformations of the components 11 and/or to avoid external interference with the internal magnetic elements 152. As can be seen from FIG. 3, the body comprises a first upper part 157 and a second lower part 158. The second lower part 158 is large enough to fit inside the first upper part 157 which is slightly larger. The sliding of the first upper part 157 on the second lower part 158 follows the lowering of the upper component 11 (represented higher up in FIGS. 3A and 3B). The deformation sensor 151 comprises two magnetic elements 152 which, as can be seen in FIG. 3A, are installed on two components 11 of the pallet which are located one above the other, that is, in the configuration in which the lower component 11 rests on the ground or on another support, and the upper component 11 is the one in direct contact with the merchandise 1 (not shown in the Figure) positioned on the pallet 10. FIG. 3B shows the deformed condition (with a graphically exaggerated lowering for the sole purpose of easier reading of the Figure) of the upper component 11 (the one on which the merchandise 1 rests). In the deformed condition (FIG. 3B) said magnetic elements 152 are brought closer to each other. Since the magnetic elements 152 are arranged with their positive poles (?+? in FIG. 3A and 3B) facing each other, the first magnetic element 152 mounted on the deformed upper component 11 pushes the second magnetic element 152 mounted on the lower component 11 downwards (by magnetic repulsion). The magnetic component 152 mounted on the lower component 11 rests on a bar 155 which in turn is connected to a spring 154. The lowering of the second magnetic component 152 causes the spring 154 to compress and the bar 155 to also lower. A signalling element 153 is mounted on the bar 155 which in static conditions (FIG. 3A) displays the indication ?OK? through a rectangular opening 156 of the body (present both in the first upper part 157 and in the second lower part 158) of the deformation sensor 151, while when the limit deformation is reached (FIG. 3B) which is defined in the design phase on the basis of the geometry of the pallet 10 and the resistance of the materials it is made of, the signalling element 153 shows through the rectangular opening 156 a symbol (?X? in FIG. 3B) indicative of the achievement of a deformation state which compromises the integrity and load-bearing capacity of the pallet 10. The deformation sensors 151 therefore indicate the achievement of the limit deformation through said signalling element 153.

In light of what has been described in relation to FIGS. 1, 2 and 3, it is clear that the production system 100 allows the technical problem linked to the difficult and time-consuming installation of a deformation sensor 151 on a pallet 10 to be overcome, allowing said deformation sensor 151 to be installed in two parts on two components 11 which are then welded together.

In other embodiments of the present invention (not shown in FIGS.

1, 2 and 3), said analog strain sensors 151 may have more than two magnetic components 152, also mounted so as to face opposite poles towards each other and to trigger a magnetic attraction mechanism instead of (as shown in FIG. 3B) magnetic repulsion. In other embodiments, said strain sensors 151 may mount different assemblies of springs 154 and bars 155 or even different mechanical components that perform the same function such as, by way of example and not limitation, fluid-dynamic pistons. In other embodiments, said strain sensors 151 may mount different signaling elements 153 also suitable for indicating intermediate states of strain such as graduated scales, color scales and/or others.

In other embodiments of the present invention (not shown in FIGS.

1, 2 and 3), said strain sensors 151 are displacement transducers powered by a rechargeable battery and report the measurements on a display mounted directly on the pallet 10.

Finally, it is clear that modifications, additions or variations obvious to a person skilled in the art may be made to the invention described herein, without thereby departing from the scope of protection provided by the attached claims.

Claims (8)

Claims 1. Production system (100) of plastic pallets (10), comprising a gas injection printing apparatus (20), a vibration welding machine (30), a hot blade welding machine (40) characterised by the fact of simultaneously producing pallets (10) with different welds and shapes through the welding of two or more components (11) each comprising an RFID tag (101) and further comprising: - a database (110) in which the identification code of each RFID tag (101) and the information on the geometry, material and production date of the relative component (11) are saved; said database (110) is designed to contain, for the RFID tag (101) of a first component (11), the identification codes of the RFID tags (101) relating to the components (11) to be welded to said first component (11); - RFID readers (120) mounted in correspondence with said vibration welder (30) and said hot blade welder (40), suitable for reading the RFID tags (101) of the components (11) to be welded together; - a control apparatus (130) for managing the printing cycles of said gas injection printing apparatus (20) and for managing the transport of the printed components (11) towards said vibration welder (30) and/or said hot blade welder (40); said control apparatus (130) for receiving data from the RFID readers (120) to verify the correct coupling between two components (11); when the RFID tags (101) read by the RFID readers (120) identify an incorrect correspondence between two or more components (11), said vibration welder (30) and/or said hot blade welder (40) are stopped by said control apparatus (130) which also sends a signal via an alert apparatus (140); said control apparatus (130) having a user interface (131) which can be consulted via a portable device such as a smartphone, a tablet and/or the like and/or via one or more displays included in the production system (100); - said warning device (140) capable of sending signals of malfunctions or incorrect correspondences between two or more components (11) through warning lights, audio systems, notifications via email, SMS and/or similar. 2. Production system (100), according to the previous claim 1, characterised in that said pallet (10) has undercuts (12) being made by welding two or more components (11) using said vibration welder (30) and/or said hot blade welder (40); said undercuts (12) are suitable for increasing the contact surface with the ground allowing for a better distribution of the loads. 3. Production system (100), according to the previous claims 1 and 2, characterised in that said pallet (10) is entirely made with recycled plastic. 4. Production system (100), according to any of the preceding claims, characterised in that it further comprises a sensor assembly station (150) in which one or more deformation sensors (151) are mounted on said pallet (10); said deformation sensors (151) are capable of measuring the bending lowering of the component (11) in direct contact with the goods (1) placed on the pallet (10). 5. Production system (100), according to any of the preceding claims, characterised in that said deformation sensors (151) operate analogically without energy supply, comprising two or more magnetic elements (152) which, installed on a first upper part (157) and a second lower part (158) two components (11) of the pallet (10) one above the other, interact by magnetic attraction or repulsion when a limit deformation defined in the design phase is reached, and indicate the deformation reached with a signalling element (153). 6. Production system (100), according to any of the preceding claims, characterised in that said strain sensors (151) are displacement transducers powered by a rechargeable battery and reporting the measurements on a display mounted on the pallet (10). 7. Production system (100), according to any of the preceding claims, characterised in that it further comprises a robotic handling apparatus (160) for said components (11) and/or said pallets (10) to completely automate the production process of said pallets (10); said robotic handling apparatus (160) comprising means for the automatic handling of said components (11) and/or said pallets (10) such as conveyor belts, robotic arms and others. 8. Production system (100), according to any of the preceding claims, characterised in that said robotic handling apparatus (160) comprises RFID readers (120) arranged on the means for the automatic handling of said components (11) and/or said pallets (10) so that, when the RFID readers (120) mounted in correspondence with said vibration welder (30) and/or said hot blade welder (40) detect an incorrect correspondence between two or more components (11), said control apparatus (130) shows the user, on the user interface (131), the position, on the robotic handling apparatus (160), of the correct components (11) whose RFID tag (101) has been detected by one or more RFID readers (120) arranged on the means for automatic handling.