Patent Description:
In plastic molding, the pieces exiting the mold are generally picked up or unloaded by means of a robot. In a similar way, said pieces can then be inserted, or loaded, in other processing islands by means of the same robot, or another robot.

<FIG> schematically illustrates a loading and/or unloading robot <NUM>, in particular in the field of plastic molding.

The robot <NUM> comprises a robotic arm <NUM>, movable along one or more axes, and having at the end thereof a connection interface <NUM>.

A gripper <NUM> can be mounted on the robotic arm <NUM>, so as to allow the robotic arm <NUM> to interact with the molded product. The gripper <NUM> comprises a connecting interface <NUM>, complementary to the connecting interface <NUM>, which allows the gripper <NUM> to be mounted and dismounted on/from the robotic arm <NUM>, according to production needs.

The gripper further comprises one or more profiles <NUM>-<NUM> which form a frame supporting one or more tools <NUM>-<NUM>, or sensors, which interact with the molded product.

The profiles <NUM>-<NUM> are assembled with each other so as to form a frame. The assembly methods are various, in general having an assembly by means of screws is however preferred, so that the profiles can be eventually reused. One or more tools and/or sensors <NUM>-<NUM> are mounted on the frame thus obtained, such as pliers, cutters, actuators, magnetic sensors, inductive sensors, etc. These can be mounted on the frame in different ways but generally having an assembly by means of screws or similar elements is preferred, so as to allow the various elements to be dismounted in the event of breakage, or when the gripper is no longer necessary.

The reasons that led to this type of solution for the frame of the gripper are different. First of all, with a limited number of profiles it is possible to configure a large number of different frames, so as to adapt to different molds. The limited number of profiles also reduces the cost. It is also possible to assemble a specific frame, and therefore a specific gripper, without resorting to methodologies that require specific skills, such as welding.

However, with the evolution of plastic molding techniques this solution has shown several critical issues.

For example, the positioning flexibility offered by the profiles <NUM>-<NUM>, both in the assembly with each other and in the positioning of the tools <NUM>-<NUM>, results in the difficulty in precisely positioning the tools <NUM>-<NUM> with each other and with respect to the coordinate system of the robot <NUM>. In particular, the position of the tools <NUM>-<NUM> must often be adjusted in the three dimensions, which makes any positioning error cumulative. By way of example, a positioning error between a first profile and a second profile connected thereto will be added to the positioning error between the second profile and the tool. In complex grippers, the precise positioning of numerous tools can therefore become a complex and time consuming activity.

Furthermore, the use of screws, or other elements that allow subsequent dismounting, for mounting the tools <NUM>-<NUM> on the profiles <NUM>-<NUM> and/or for the connection of different profiles to each other, has the disadvantage that vibrations and/or shocks induced by the processing, by thermal variations, by the transport of the gripper, by a possible fall of the same, can result in a movement of the tools <NUM>-<NUM>, and consequently in the need to periodically check their correct positioning.

Finally, the shape itself of the profiles <NUM>-<NUM>, generally of a rectilinear shape, often introduces limitations and/or complications on how to position the tools <NUM>-<NUM> in space. In fact, an ideal positioning with respect to the shape of the molded product is often not possible due to the limitations introduced by the shape of the profiles. In order to try and reduce, at least in part, this disadvantage, the tools <NUM>-<NUM> are developed in countless different configurations, so as to convey flexibility limited by the shape of the profiles, however increasing the acquisition costs of the various different tools.

The invention was therefore developed to solve at least in part one or more of these problems and to, more generally, offer a new way of conceiving and realising grippers that is better adapted to modem molding.

Grippers according to the state of the art are known, for instance, from documents <CIT>, "<NPL>, <CIT> and <CIT>.

The present invention is based on the generic concept according to which, instead of using profiles to make the frame of the gripper, this can be made of plastic material, by a 3D printing.

Specific embodiments of the invention are defined by the independent claims.

According to example, the invention can refer to a method for the realisation of a gripper for a plastic mold loading and/or unloading robot, the method comprising the steps of: acquiring a mold project, designing the gripper based on the mold project, realising the gripper by a 3D printing.

In this way it is advantageously possible to obtain a precise gripper, easily reproducible and with implementation possibilities not obtainable by gripper according to the state of the art.

In some implementation embodiments, the step of designing the gripper may comprise the steps of: designing, as an integral part of the gripper, supports for pneumatic ducts, and/or designing, as an integral part of the gripper, supports for electric connections.

In this way it is advantageously possible to ideally configure and position the supports, with respect to the configuration of the gripper and the tools thereof. In some implementation embodiments the step of designing the gripper may comprise the step of: designing, as an integral part of the gripper, support elements for a molded object.

In this way it is advantageously possible to obtain supports with a specific shape and positioning so as to interface with the molded object.

In some implementation embodiments, the step of realising the gripper may comprise the realisation of the gripper with material PA6 or with a material based on Polylactic Acid and additivated with graphene.

In this way it is advantageously possible to obtain a gripper with ideal mechanical characteristics.

A further implementation embodiment of the invention may relate to a gripper for a plastic molding loading and/or unloading robot, where the gripper is made by a 3D printing.

In some implementation embodiments the gripper may further comprise a support element for a molded object.

In this way it is advantageously possible to obtain supports for interfacing and/or supporting the molded object.

In some implementation embodiments, the support element can have a shape substantially complementary to at least part of the molded object.

In some implementation embodiments the gripper may further comprise a plurality of supports for pneumatic ducts and/or electrical connections made as hollow sections of the gripper.

In this way it is advantageously possible to ideally configure and position the supports, with respect to the configuration of the gripper and the tools thereof. In some implementation embodiments the gripper may further comprise a plurality of structural lamellae, where the supports are made as hollow sections of the structural lamellae.

In this way it is advantageously possible to integrate the supports in the structure of the gripper so as to let slide the elements supported in the proximity of the gripper, thus keeping the overall dimensions of the gripper contained.

In some implementation embodiments the gripper may further comprise a plurality of supports for pneumatic ducts and/or electrical connections made with the same material and as an integral part of the gripper.

In this way it is advantageously possible to realise the supports with the same manufacturing process as the gripper, without introducing additional and/or external elements which would increase the cost and complexity of the gripper.

Further characteristics and advantages of the invention will become clearer from the examination of the following detailed description of preferred but not exclusive embodiments, illustrated only by way of non-limiting example, with the support of the accompanying drawings.

In the drawings the same reference numbers identify the same components. In particular:.

<FIG> schematically illustrates a method <NUM> for the realisation of a gripper <NUM> according to an implementation embodiment of the invention. In particular, the method <NUM> comprises a first step S2100 consisting in acquiring a mold project, preferably in a CAD format. Any CAD format, in particular a format for 3D CAD, for example an IGS or STP format, can be used.

Thanks to this step it is possible to obtain the shape of the mold, as well as the shape of the molded object, which allows designing a gripper <NUM> that takes into consideration these elements, as well as the kinematic mechanism of the mold and the movement needed by the gripper <NUM> to pick up the molded object.

Thanks to this step it is therefore advantageously possible to view all the data necessary for the design of the gripper <NUM> and, if necessary, to proceed to the next step, that is to the design step S2200 by using the same CAD environment, which advantageously allows to considerably reduce the design times.

In step S2200 the gripper <NUM> is then designed based on the mold project. The possibility of designing the gripper in an integrated manner in the 3D file of the mold makes it possible to view the kinematic mechanism of the mold comprising the extraction of the molded piece and the operation of the gripper <NUM>; all in a single environment, therefore with a real view of the process.

The gripper <NUM> is then made in a step S2300 by a 3D printing. In this way, the gripper <NUM> can be advantageously made in a desired number of copies, all identical, in a short period.

The method <NUM> allows obtaining a whole series of advantages not obtainable with the grippers of the state of the art.

In particular, it is advantageously possible to obtain a gripper <NUM> which has a shape adapted to the mold and/or the molded piece, which guarantees an ideal grip of the aforementioned piece.

Furthermore, thanks to the possibility of realising the project for the gripper <NUM> directly based on the CAD project of the mold, an ideal correspondence between the gripper <NUM> and the mold and/or the molded product can be guaranteed, in contrast to the gripper <NUM> of the state of the art which, being made by hand, and with profiles having predetermined shapes, offers significantly reduced flexibility and design precision. This advantageously allows reducing waste caused by the instability and/or inaccuracy of the gripper <NUM> with traditional systems.

Thanks to the design of the gripper <NUM> integrated in the mold design, and thanks to the design flexibility allowed by the realisation by 3D printing, it is possible to improve the kinematic mechanism of the gripper <NUM>, ensuring a greater speed of exit of the robotic arm outside the overall dimensions of the press with the consequent reduction of the molding cycle times.

It is also possible to guarantee contemporaneity and precision of sprue cutting, it being also improved as to the cycle times of the press, thus zeroing the costs for equipment placed downstream for cutting the same sprue.

The method <NUM> also allows realising a desired number of grippers, identical to each other, in rapid times. This allows, on the one hand, replacing a repeated work of toolmakers with a single design by a single designer. The setup times of the gripper <NUM> are also greatly reduced, with a reduction in costs, since it is no longer necessary to equip each gripper <NUM> in a complex way, in particular ensuring not only the position but also the correct orientation in space of the tools <NUM>-<NUM>, but it is sufficient to insert the tools in the target seats. In the event of breakage, the gripper <NUM> can also be easily and quickly replicated, which allows it to be replaced immediately, without any checks or adjustments.

Through these advantages, machine downtime and production loss are substantially reduced, if not zeroed, with a clear reduction in costs, while guaranteeing an increase in quality.

Furthermore, in the case of moldings made at third-party factories, it is not necessary to rely on the skills of local toolmakers, for implementing grippers in place, or physically send the ready-made grippers, it will be instead sufficient to transfer the gripper project <NUM> obtained under step S2200, to allow the implementation of step S2300 in a different location.

The customization of the gripper <NUM> as a function of the product also leads to the further advantage of making the company more competitive with respect to the competition as it inevitably strengthens the bond with the customer who would have a further constraint in having other companies molded his product.

Furthermore, the method <NUM> allows concentrating the design of the gripper <NUM>, under step S2200, in one professional role.

In some implementation embodiments, the step of designing S2200 the gripper <NUM> comprises one or more of the following steps.

Starting from the 3D file of the mold positioned in the molding press and positioned in the extraction position, all the 3D of the complete mold is taken in order to have all the overall dimensions and precision.

In a design step, the type of gripper <NUM> to be realised is defined, that is if it only picks up from the mold and deposits, for example on a conveyor belt or in a collection container, or if the cut of the sprue must also be considered, or if it is necessary to insert a component that must be overmolded or to insert a dimensional check with a camera, etc. In a following step the tools <NUM>-<NUM> to be added to the gripper <NUM> are chosen, for example suction cups, pliers, pistons/actuators, shears for sprue cutting, cameras for dimensional check etc..

In a design step, supports <NUM> for pneumatic ducts and/or supports <NUM> for electrical connections are designed as an integral part of the gripper. In particular, depending on the tool <NUM>-<NUM> it is proceeded with the design of the interlocking through compressed air ducts, in the case of pneumatic actuators, or of the power supply and/or of the control and/or feedback signals, in the case of air and electrical sensors, cameras, etc. For example, clips can be designed as an integral part of the gripper <NUM> which allow the housing of the air channels or of the signal or power conductors so as to prevent said cables or tubes from interfering in the normal operating function of the gripper <NUM> or complicating the tooling activities of the injection press.

In a subsequent step a compressed air manifold can be designed - with adequate numbering for the various functions in order to avoid errors in the interlocking wiring - for the orderly sorting of the air pipes of the various users.

In one design step, compressed air ducts can be designed integrated with the gripper <NUM>, for example such as empty channels in the material printed with a 3D printer, so as to avoid the need for external ducts.

In a design step, support elements <NUM>, <NUM> for a molded object can be made as an integral part of the gripper <NUM>. In particular, it is advantageously possible to form some parts of the gripper <NUM> so as to have a complementary shape to some parts of the molded object which must be taken and/or processed by the gripper <NUM>. This allows the gripper to provide stable support to the molded object and to allow more precise processings thereon, avoiding the movement and/or flexion thereof.

In a design step one or more connection interfaces <NUM> can be realised for the connection of the gripper <NUM> to the robot, in particular in such a way that it can be positioned on different robots. As an example, a single connection interface <NUM> can be implemented for assembly on Engel automation robots, Piovan Star automation robots and Tecnomatic automation robots.

In some implementation embodiments, the step of realising the gripper <NUM> may comprise one or more of the following steps.

The file generated at the end of the design S2200 provides the basis for physically realising the gripper <NUM> by 3D printing. Through 3D printing management software, the file is transformed into an STL file. Once the correct and printable STL file is obtained, it is transferred to the 3D printer which starts the printing process and the required copies are made.

Various 3D printing technologies have been evaluated for the gripper <NUM>, for example rapid prototyping in stereolithography and sintering, as well as various thermoplastic materials. Stereolithography and sintering have proven to be less advantageous, due to the fragility and difficulty of making different colours of the same product. It will be clear that different 3D printing technologies exist and the expert in the sector will be able to select from time to time the most suitable process for the type of product to be made, in particular according to the specific use and also according to the type of material that the designer considers as the most performing in the specific context. Their main differences are related to the way in which the layers are printed. In some first practical realisations the inventors have identified as particularly advantageous the 3D printing process known as SLS, that is Selective Laser Sintering, which is an additive manufacturing technology that uses a laser beam to sinter plastic powder inside a closed room. Other technologies that have proved to be particularly advantageous are FDM, i.e. Fused Deposition Modeling, or DLP, i.e. a liquid polymer tank that is exposed to the light of a DLP projector under conditions of inattinic light. The exposed liquid polymer hardens. The building plate then moves downward by small increments and the liquid polymer is again exposed to light. The process is repeated until the pattern is built. The liquid polymer is then drained from the tank, leaving the solid model.

As regards the printing materials, the same considerations made above apply, that is, an expert in the 3D printing sector will, from time to time, based on the needs related to the specific application, select the most suitable material. By way of example, the inventors have however noted a particular advantageous result achieved with PA6, Nylon. In other advantageous implementation embodiments, GRAFYLON® 3D Ø <NUM>,<NUM> - <NUM> Model 1PLAGRAF7 was used, a 3D printing material based on PLA, that is Polylactic Acid, additivated with graphene, to offer excellent mechanical performance and aesthetics. In contrast, ABS, a non-structural thermoplastic, proved to have less resistance to stress than PA6. As an alternative, the material ULTEM was considered comparable to the yield obtained with PA6 but proved to be more expensive and difficult to find for the use of 3D printers.

<FIG>, <FIG> schematically illustrate a gripper <NUM> according to an implementation embodiment of the invention. <FIG> shows the gripper <NUM> together with two molded objects OGG. <FIG> also shows the tools <NUM>-<NUM> mounted on the gripper <NUM>. <FIG> shows the rear side of the gripper <NUM>. <FIG> illustrates the configuration including pneumatic ducts and/or electrical connections.

In particular, the gripper <NUM> allows processing and extracting from the mold two objects molded simultaneously. It will be clear that in alternative embodiments of the invention, the number of molded objects to be processed and extracted from the mold can be any number. It will also be clear that it is not necessary for the gripper to be configured to process and extract from the mold, it is sufficient that it can extract from the mold, for completeness of description it has been preferred to illustrate an implementation embodiment which also allows processing.

The gripper <NUM> comprises a connection interface <NUM> that allows the connection of the gripper <NUM> to different robots. In particular, as is visible, the connection interface <NUM> is substantially a flange comprising several holes, at different distances, which correspond to as many standards of different robots. This configuration advantageously allows the gripper <NUM> to be used with various robots from different manufacturers.

The gripper <NUM> further comprises two arms, <NUM>, <NUM>, having a substantially identical function, whereby only one arm will be described.

The arm <NUM> comprises a support element <NUM>, intended to support, at least in part, a molded object OGG. The support element <NUM> has a complementary shape to at least part of the molded object OGG.

In particular, in the illustrated implementation embodiment, the molded object OGG has a substantially cylindrical cavity and the support element <NUM> has a lamellar shape with the external part of the lamellas <NUM> defining a shape at least partially substantially cylindrical. Advantageously, the size of the cylindrical lamellar shape substantially corresponds to that of the cylindrical cavity, so as to allow the object OGG to be supported at least partially by the support element <NUM>. In some implementation embodiments, making an advantageous use of the flexibility of the lamellae <NUM>, it will be possible to have a size of the cylindrical lamellar shape that is slightly higher than that of the cylindrical cavity, so as to exert a slight pressure on the internal part of the cylindrical cavity in order to support the object OGG more stably.

The arm <NUM> further comprises a further support element <NUM>, intended to support, at least in part, a molded object OGG. The support element <NUM> has a complementary shape to at least part of the molded object OGG.

In particular, in the illustrated implementation embodiment, the molded object OGG has a substantially cylindrical external surface and the support element <NUM> has a concave shape which defines a shape substantially corresponding to a cylinder arc. Advantageously, the size of the cylinder arch shape substantially corresponds to that of the substantially cylindrical external surface, so as to allow the object OGG to be supported at least partially by the support element <NUM>.

The presence of the support element <NUM>, <NUM> allows the gripper to carry out processings on the molded object OGG, for example the cutting of the sprue, which normally would instead be performed in a subsequent processing step. In particular, the possibility of guaranteeing a stable support to the object OGG, with support elements <NUM>, <NUM> having surfaces designed in a substantially complementary way to the shape of the object, whose realisation is possible thanks to the 3D printing process, allows ensuring a precise and stable position of the object OGG on the gripper, which makes processings on the gripper <NUM> possible, which would not otherwise be possible with a state-of-the-art gripper.

As is visible in <FIG>, the gripper <NUM> can mount a plurality of tools <NUM>-<NUM>, housed in respective seats <NUM>-<NUM>. The tools can be of any type, and it will be clear that the seats will be designed with the appropriate dimensions and orientation for each respective tool. In the illustrated implementation embodiment, the tools <NUM>-<NUM> are suction cups while the tool <NUM> is a plier. It will be clear that other real known tools can be implemented in the gripper <NUM>.

As is visible in <FIG>, in some implementation embodiments, the gripper <NUM> comprises a plurality of supports <NUM> for pneumatic ducts and/or electrical connections.

Generally these supports have a shape such that it is possible to support the ducts and/or connections by inserting them inside the support and keeping them in position by means of an elastic deformation of the support and/or of the element to be supported. In other words, the supports <NUM> act as "clips" inside which the elements to be supported are positioned. More generally, the supports <NUM> are characterized by being formed of the same material that forms the gripper <NUM>, thus allowing an integrated realisation of the gripper <NUM> and the supports <NUM>.

In the illustrated implementation embodiment the supports <NUM> are generally hollow sections in structural lamellae <NUM> of the gripper <NUM>, these hollow sections having a substantially circular shape, with an opening on a circular arc having a size comprised between <NUM> and <NUM> degrees.

The structural lamellas <NUM> are basically in the form of a plane with extension substantially perpendicular to the plane defined by the two maximum dimensions of the gripper <NUM>. Thanks to this configuration, the structural lamellae <NUM> allow conferring stability and sturdiness to the gripper <NUM>, limiting the weight thereof. In the illustrated implementation embodiment there are two groups of structural lamellas <NUM> oriented in a crossed manner with each other and, preferably, in a substantially perpendicular manner, increasing the sturdiness of the gripper <NUM>. Thanks to this configuration, it is also possible to realise channels, between two parallel structural lamellae <NUM>, inside which the elements to be supported slide, which are then held in position by the supports <NUM> made in the crossed structural slats <NUM>.

This configuration allows organizing in a stable manner the elements to be supported, such as pneumatic ducts and/or electrical connections. As is visible in 3D figure, the pneumatic ducts and/or electrical connections <NUM> can be positioned and held in position by the supports <NUM>, thus avoiding that these elements can move and accidentally come into contact with other elements. The realisation of the supports <NUM> as a cavity inside the lamellae allows the pneumatic ducts and/or electrical connections to be conveyed at the same level as the lattice formed by the structural lamellae <NUM>, thus keeping the external dimensions of the gripper <NUM> limited. However, it will be clear that other forms and/or positions of the supports <NUM> are possible, for example of the supports <NUM> with a hollow shape substantially like a C, where the cavity of the shape allows the insertion of the pneumatic duct and/or of the electrical connection <NUM>, and made on any surface of the gripper <NUM>.

As is clear from the foregoing description, compared to a traditional gripper, an advantage offered by the present patent application is the versatility of the gripper <NUM>, which can be designed and manufactured for the specific mold. A further advantage is the reduced weight, which makes the robot work easier, faster, cheaper and allows using robots with lower specifications, reducing their cost.

A further advantage of the gripper <NUM> consists of the realisation time. The inventors have determined that with less than <NUM> hours of design, obviously dependent on the specifications of the gripper <NUM> and the object, are necessary to precisely design the optimal gripper <NUM> for the specific mold. Following this design step S2200, the 3D printing step S2300 is relatively fast and, above all, can be done in parallel for different grippers <NUM>. This way of realising the gripper <NUM> does not require adjustments in the tooling step since the precision thereof is studied by CAD integrating it with the mold process to which it is dedicated.

It follows that precision and the absence of skilled labor are other advantageous elements as well as the possibility of integrating in the same structure of the gripper <NUM> different tools that are difficult to integrate into the gripper known by the state of the art due to precision limitations, set-up speed, and design and manufacturing flexibility of the grippers.

Furthermore, thanks to the specific design and construction of a mold, with the invention it is possible to realise a gripper <NUM> with more elaborate geometries and with reduced dimensions compared to the traditional mechanical gripper.

<FIG> schematically illustrates a perspective view of a gripper <NUM> according to an implementation embodiment of the invention.

In particular, the gripper <NUM> differs from the gripper <NUM> thanks to the presence of one or more levelling elements <NUM>, <NUM> inserted in special seats made as an integral part of the gripper <NUM>. In the illustrated implementation embodiment, the levelling elements <NUM>, <NUM> are bubble levels. Thanks to the possibility of realising the appropriate seats while designing the gripper <NUM>, it is possible to realise the seats with a precise orientation such that, when the gripper is in use, for example, in the default mounting position on the robotic arm <NUM>, the levelling elements <NUM>, <NUM> indicate to the operator if the positioning of the gripper <NUM> corresponds to a predetermined direction of the gripper in space. For example, it will be possible to realise the seats of the levelling elements <NUM>, <NUM> so that, during the mounting step of the gripper on the robotic arm, the levelling elements <NUM>, <NUM> respectively indicate a correct vertical and horizontal alignment, thus confirming to an operator that the gripper <NUM> was assembled on the robotic arm <NUM> correctly.

Claim 1:
Method for the realisation of a gripper (<NUM>) for a plastic molding loading and/or unloading robot, the method comprising the steps of:
acquiring (S2100) a mold project,
designing (S2200) the gripper (<NUM>) based on the mold project,
realising (S2300) the gripper (<NUM>) by a 3D printing,
characterized in that
the step of designing (S2200) the gripper (<NUM>) comprises the steps of:
designing, as an integral part of the gripper (<NUM>), supports (<NUM>) for electrical connections made as hollow sections of the gripper (<NUM>),
wherein the gripper (<NUM>) further comprising a plurality of structural lamellae (<NUM>), and supports (<NUM>) are made as hollow sections of the structural lamellae (<NUM>).