The invention relates to gripping systems and devices for handling and moving objects and in particular relates to a suction cup gripping system suitable for gripping and moving objects.

Gripping and moving systems are known and widely used that use suction cups to grasp objects by adhering firmly to their external, substantially flat and non-porous surface.

These suction cup gripping systems are, for example, widely used in automatic machines for sheet metal cutting and/or punching, in particular to load the metal sheets onto a work table of the machine and to remove from this table the final pieces thus obtained after the cutting and/or punching.

As is known, creating a negative pressure inside a suction cup placed in contact with the external surface of an object generates a gripping force which, if it is greater than the weight of the object itself, allows it to be held firmly and then lifted and moved with relative safety. The negative pressure or partial vacuum is realized inside the cavity formed by the suction cup and the external surface of the object by connecting with a vacuum source, typically a vacuum pump.

For this purpose, it is very common to use vacuum pumps or Venturi vacuum generators or ejectors that use compressed air and the Venturi principle to generate the vacuum. More precisely, such pumps comprise a Venturi nozzle or tube (converging/diverging duct) supplied by, and crossed by, compressed air and connected at a narrowing or constriction section thereof, in which a negative pressure or partial vacuum is generated, to the inside of the suction cup.

A valve is generally provided on the compressed air supply line, configured and selectively operable to supply the compressed air to the Venturi ejector and generate the vacuum needed for the suction cup to grasp and move the piece or to stop this supply of compressed air and to vent the suction cup, that is, to connect it to the external environment so as to allow the suction cup to release the piece.

Venturi vacuum generators are economical and reliable, since they have no moving parts and are not subject to wear and also have reduced dimensions and weight. Furthermore, unlike rotary vacuum pumps, Venturi vacuum generators can operate in a discontinuous manner, i.e. only when the suction cups need the negative pressure, which they can achieve, given the reduced volume of the internal cavities of the suction cups, in a very short time. A disadvantage of gripping systems with suction cup and Venturi vacuum generator is that the negative pressure, or partial vacuum, must be maintained inside the suction cup by supplying the Venturi ejector with compressed air throughout the duration of the gripping and moving of the object. In the case of gripping and moving systems in which the gripping of the pieces must be maintained for a relatively long period of time (for example 20-30 s), the consumption of compressed air, and therefore of electrical energy, necessary to produce said compressed air through suitable compressors, is very high and therefore the operation of such systems is quite expensive.

An object of the present invention is to improve suction cup gripping systems, in particular associated with a Venturi vacuum generator and therefore supplied and operated by compressed air.

Another object is to realize a device and a suction cup gripping system that allows significant reduction in the consumption of compressed air during operation, in particular during the gripping and moving of an object.

A further object is to provide a suction cup gripping system that allows objects of various sizes and weight to be gripped and held firmly, reliably and safely.

Another object is to make a gripping system having a simple, robust and economical construction.

In a first aspect of the invention a suction cup gripping system according to claim 1 is provided.

In a second aspect of the invention a suction cup gripping system according to claim 9 is provided.

The invention can be better understood and implemented with reference to the attached drawings which illustrate exemplary and non-limiting embodiments thereof, in which:

Figure 1 is a front view of a gripping device of the suction cup gripping system of the invention;

Figure 2 is a plan view from above of the gripping device of Figure 1 ;

Figure 3 is a section according to plane III-III of Figure 1 ;

Figure 4 is a perspective view of the gripping device of Figure 1 associated with a supporting structure of the suction cup gripping system;

Figure 5 is a pneumatic diagram of the suction cup gripping system of the invention comprising a plurality of gripping devices of Figure 1 ;

Figure 6 is a perspective view of the suction cup gripping system of Figure 5;

Figure 7 is a pneumatic diagram of a variant of the suction cup gripping system of the invention;

Figure 8 is a pneumatic diagram of a further variant of the suction cup gripping system.

With reference to Figures 1 to 4, a suction cup gripping device 1 of the suction cup gripping system 100 of the invention is illustrated; the suction cup gripping device 1, or gripping device, comprises at least one gripping suction cup 2, or suction cup, provided with an internal cavity 3 and adapted to abut an external surface 51 of an object 50 to be gripped, in particular a level and/or flat object with a non-porous external surface, such as for example a metal sheet or a piece obtained by cutting and/or punching a metal sheet.

The gripping device 1 also comprises a Venturi vacuum generator 10, or Venturi ejector, connectable to a line or source of compressed air 30 and in flow connection with the internal cavity 3 of the suction cup 2. The Venturi vacuum generator 10, of known type and not described in further detail, is configured to generate a negative pressure or partial vacuum in the internal cavity 3 when it is supplied with compressed air and when the suction cup 3 engages the external surface 51 of the object 50. More precisely, a narrowing section of a converging/diverging duct of the Venturi vacuum generator 10, in which a negative pressure or partial vacuum is generated as the compressed air passes through, is in flow connection with the internal cavity 3 of the suction cup 2.

The Venturi vacuum generator 10 is for example of the multi-stage type, in particular it comprises two or three stages for realizing a higher value of partial vacuum or negative pressure inside the internal cavity 3, for example comprised between -0.85 kPa and -0.65 kPa i.e. between 0.15 and 0.35 kPa (bar) in absolute value.

The gripping device 1 further comprises a release valve 11 and a check valve 12. The release valve 11 is in flow connection with the internal cavity 3 and is operable to connect the latter to an external environment or to the source of compressed air 30 in order to eliminate the partial vacuum inside the internal cavity 3, and thus allow releasing the object. The check valve 12, or one-way valve, is in flow connection with and interposed between the Venturi vacuum generator 10 and the internal cavity 3 and is configured to prevent air from entering the internal cavity 3 when the Venturi vacuum generator 10 is not supplied with compressed air, as better explained below.

The gripping device 1 comprises a casing 4, for example fixed to a connecting element 5 of the suction cup 2, suitable to house and contain the Venturi vacuum generator 10, the release valve 11 and the check valve 12.

The casing 4, having for example a prismatic shape, comprises a first connection 6, in flow connection with a supply inlet of the Venturi vacuum generator 10, a second connection 7, in flow connection with the release valve 11 , a third connection 8 for the flow connection of the internal cavity 3 of the suction cup 2 with the Venturi vacuum generator 10 and the release valve 11.

The casing 4 is further provided with a fourth connection 9 in flow connection with the Venturi vacuum generator 10 and the internal cavity 3.

The casing 4 also comprises a fifth connection 19 in flow connection with a discharge outlet of the Venturi vacuum generator 10.

The first connection 6 is connectable to the compressed air line 30, in particular via a first supply duct 41, for supplying compressed air to the Venturi vacuum generator 10 so as to generate a partial vacuum inside the internal cavity 3 of the suction cup 2.

The second connection 7 in the illustrated embodiment is also connectable to the compressed air line 30, in particular by means of a second supply duct 42, to send compressed air to the release valve 11 which, when activated, sends the air into the internal cavity 3 in order to eliminate the partial vacuum in the internal cavity 3 and thus allow the release of the object. The third connection 8 is connected to the Venturi vacuum generator 10, in particular to its narrowing section, by a first duct 14 and to the release valve 11 by a second duct 15 which is connected to the first duct 14 at a branch point 16.

The fourth connection 9 connects the Venturi vacuum generator 10 and the internal cavity 3 to a manifold 50 provided with a vacuum sensor 13 or directly to the vacuum sensor 13, as better explained in the description below.

The fifth connection 19, in flow connection with the discharge outlet of the Venturi vacuum generator 10, can be connected, for example, to a silencer 17 in such a way as to reduce the noise generated by the compressed air leaving the Venturi vacuum generator 10 and dispersed into the environment.

The check valve 12 is inserted in the first duct 14 in the portion thereof that is between the Venturi vacuum generator 10 and the branch point 16.

A filter 18 is inserted in the first duct 14 in the section between the branch point 16 and the third connection 8.

The release valve 11 is for example a pneumatic valve, in particular a two-way, two-position pneumatically operated valve. In particular, the release valve 11 is normally closed i.e. it closes the flow connection between the second connection 7 and the internal cavity 3 when it is not pneumatically supplied and controlled. Conversely, when the release valve 11 is supplied with compressed air coming from the pneumatic supply line 30, it is switched to the open operating position so as to open the flow connection between the second connection 7 and the internal cavity 3 for the entry of compressed air into the internal cavity.

The casing 4 also comprises a fastening element 28 for connecting the gripping device 1 to the suction cup gripping system 100. The fastening element 28 is in particular aligned and opposite the connecting element 5 of the suction cup 2.

With particular reference to Figure 3, the suction cup 2 comprises a body 20 provided with an upper portion 21 and a deformable central portion 22, in particular compressible and/or crushable along a direction parallel to a longitudinal axis X of the suction cup 2, and defining the internal cavity 3. The connecting element 5 is connected to the upper portion 21 and is provided with an internal duct 25 for the passage of air.

The central portion 22 includes a peripheral edge 22a that surrounds a lower access opening to the internal cavity 3 and is configured to abut the external surface 51 of the object 50 to be picked up.

The suction cup 2 further comprises a stop element 23 positioned in the internal cavity 3, fixed to the upper portion 21 and suitable to abut the external surface 51 of the object 50 when the suction cup 2 engages said external surface 51 and the internal cavity 3 is placed in negative pressure, so as to limit a deformation or crushing of the central portion 22. The stop element 23 comprises a respective central duct 24 provided with axial openings 26 and lateral openings 27 for the passage of air.

With reference to Figure 5, the suction cup gripping system 100, or gripping system, of the invention comprises a plurality of gripping devices 1, for example seven, as described above and illustrated in Figures 1 to 4, valve means 37, 38 in flow connection with the Venturi vacuum generators 10 and the release valves 11 of the gripping devices 1 for supplying compressed air selectively to said Venturi vacuum generators 10 or said release valves 11. In particular, each gripping device 1 includes at least one gripping suction cup 2 adapted to abut the external surface 51 of an object 50 to be gripped and provided with an internal cavity 3, a Venturi vacuum generator 10 connectable to the compressed air line 30 and in flow connection with the internal cavity 3 to generate a negative pressure or partial vacuum in the internal cavity 3 when supplied with compressed air and when the gripping suction cup 3 is engaged to the external surface 51 of the object 50, a release valve 11 in flow connection with the internal cavity 3 and operable to connect the internal cavity to an external environment or to the compressed air line 30 in order to eliminate the partial vacuum in the internal cavity 3 and a check valve 12 in flow connection and interposed between the Venturi vacuum generator 10 and the internal cavity 3 and configured to prevent the air from entering the internal cavity 3 when the Venturi vacuum generator 10 is not supplied with compressed air.

The gripping system 100 further comprises a manifold 50 in flow connection with the internal cavities 3 of the suction cups 2 of the plurality of gripping devices 1, in particular via respective measuring ducts 43, and a vacuum sensor 13, in flow connection with the manifold 50 and suitable to measure a value of partial vacuum inside the manifold 50 and therefore inside the internal cavities 3 of suction cups 2.

The gripping system 100 also includes a control unit 40 connected to valve means 37, 38 and vacuum sensor 13 and configured to control the valve means 37, 38 so as not to supply compressed air to the Venturi vacuum generators 10 of the gripping devices 1 when the pressure sensor 13 detects a value of partial vacuum in the manifold 50 and therefore in the internal cavities 3 of the suction cup 2 that is greater than or equal to a defined first threshold value Pl, i.e. an absolute pressure inside the internal cavities 3 of the suction cups 2 lower than said defined first threshold value Pl. The first threshold value Pl is for example -0.80 kPa and -0.65 kPa in relative value or 0.20 kPa in absolute value.

The control unit 40 can be the control unit of an operating machine, for example a machine for cutting and/or punching metal sheets, on which the gripping system 100 of the invention is installed and operated.

It should be noted that the plurality of gripping devices 1 of the gripping system 1 of the invention, which are supplied with compressed air by the same valve means 37, 38 and share a single vacuum sensor 13 mounted on the manifold 50 to which the Venturi vacuum generators 10 of gripping devices 1 are connected, define a gripping zone or area. In particular, the gripping system 100 allows one or more objects 50 contained within said gripping zone to be picked up or moved at the same time.

Valve means 37, 38 comprise, in particular, a pair of valves activated and operated by the control unit 40, in particular a pair of electrically operated valves of the known two-way and two-position type, connected to the compressed air supply line 30 and to an air exhaust line 31. For example, the valve means comprise a pair of pneumatic valves having solenoids with indirect operation, i.e. pneumatically switched into the two operating positions on the basis of electrical signals sent by the control unit 40. In particular, the valves are connected to a pneumatic switching line 33 and to a switching exhaust line 32. In the illustrated embodiment, the valve means comprise a first valve 37 associated with the Venturi vacuum generator 10 and a second valve 38 associated with the release valve 11.

The first valve 37 is for example of the normally open type, i.e. when it is not electrically activated it keeps the flow connection between the pneumatic supply line 30 and the Venturi vacuum generator 10 open, while it connects the Venturi vacuum generator to the exhaust line 31 when it is activated.

Conversely, the second valve 38 is of the normally closed type, i.e. when it is not activated it keeps the release valve 11 in flow connection with the exhaust line 31, while when it is electrically activated connects the release valve 11 to the pneumatic supply line 30.

Each gripping device 1 further includes a respective adjustment nozzle 35 with calibrated hole, in particular with a size between 0,2 and 0,4 mm, in particular equal to 0,3 mm, said adjustment nozzle 35 being in flow connection with and interposed between the internal cavity 3 of suction cup 2 and the manifold 50 and suitable to limit an air flow entering the manifold 50, in particular when the corresponding suction cup 2 is not engaged with the external surface 51 of the object 50. More precisely, the adjustment nozzle 35 with a calibrated hole for the passage of the air flow makes it possible to limit the loss of vacuum in the manifold 50 in the event that the associated gripping device 1 is not gripping the object 50, since it reduces the suction of air by the other gripping devices 1 through said suction cup 2 not gripping.

In particular, each adjustment nozzle 35 is connected to the fourth connection 9 of the casing 4 of the respective gripping device 1 and is in flow connection with the Venturi vacuum generator 10 and the internal cavity 3. Therefore, the adjustment nozzle 35 is inserted in the respective measurement duct 43, interposed between the fourth connection 9 and the manifold 50.

The vacuum sensor 13 comprises, for example, a vacuum switch of known type suitable to detect the first threshold value Pl and a further first threshold value Pl' and to send related signals to the control unit 40 to control the valve means 37, 38 so as to maintain in the manifold 50 and therefore in the internal cavities 3 of suction cups 2 a value of partial vacuum substantially equal to the first threshold value Pl or the further first threshold value Pl' in particular according to the characteristics of the object 50 to be picked up and moved. The vacuum switch 13 is therefore able to automatically detect two different vacuum values to allow the gripping force of suction cups 2 to be managed, for example as a function of a thickness of the object or objects (sheets, plates, slabs, ...) to be moved. For example the first threshold value Pl may be a lower vacuum value suitable for picking up and moving thin sheets (up to 0,8 mm), in particular without deforming them, and the further threshold value Pl' may be a higher vacuum value suitable for picking up and moving sheets of thickness greater than 0,8-1 mm.

As illustrated in Figure 6, the suction cup gripping system 100 of the invention comprises a supporting frame 101 configured to support the plurality of gripping devices 1, in particular arranged spaced apart according to a plurality of parallel rows.

The operation of the gripping system 100 of the invention, in a procedure of gripping and moving for example a single object 50 provided with an external surface 51, suitable to interact with the gripping suction cups 2, i.e. for example a flat and non-porous surface, provides an initial step of approach and positioning of the gripping devices 1, in which the suction cups 2 are positioned on the external surface 51. More precisely, the peripheral edge 22a of the central portion 22 of each suction cup 2 abuts the external surface 51 of the object 50.

It should be noted that since the plurality of gripping devices 1 of the gripping system 100 defines a gripping area, the gripping system 100 of the invention allows a plurality of distinct objects present inside the gripping area to be gripped and therefore moved.

In order to grip the object 50 the first valve 37 is arranged in the open position so as to supply compressed air coming from the supply line 30 to the Venturi vacuum generators 10 that suck air from the internal cavities 3 of suction cups 2 of gripping devices 2 so creating a negative pressure, which allows the suction cups 2 to adhere strongly to the external surface 51 of the object 50. In this way, each gripping device 2 generates a gripping force that is directly proportional to the pressure difference between ambient pressure and pressure inside the suction cup 2.

The overall gripping force exerted by all the gripping devices 1 acting simultaneously on the object 50, if greater than the weight force of the object 50, allows the gripping system 100, fixed to a suitable handling apparatus, to lift and move the object 50.

When the value of the negative pressure or partial vacuum inside the internal cavity 3 of the suction cup 2, measured by the vacuum sensor 13 connected to the control unit 40, reaches and exceeds the first threshold value Pl (for example equal to -80 kPa) or the further first threshold value Pl', such as to generate the required gripping force, the first valve 37 can be switched to the closed position by the control unit 40. In this way, the valve 37 does not further supply the Venturi vacuum generators 10 with unused compressed air that will be dispersed into the environment. The compressed air, after passing through the converging/diverging duct of each Venturi vacuum generator 10, in fact escapes into the external environment through the fifth connection 19 of the casing 4.

The internal cavities 3 of the suction cups 2 of the gripping devices 1 are however kept in negative pressure thanks to the respective check valves 12 that close the first ducts 14 and prevent air from entering said internal cavities 3.

Numerous tests carried out by the applicant have shown, with each gripping suction cup 2 adhering to the external surface 51 of an object 50 and with an initial negative pressure value of about -0.89 kPa, a progressive and slow decrease of the negative pressure over time, i.e. an increase of the absolute pressure in the internal cavity 3 over time. More precisely, it has been found that the negative pressure, and therefore the relative gripping force, are maintained for at least 20/25 min at values such as to allow reliable and safe holding and moving of an object 50, such time being considerably longer than the average duration of the procedures for gripping and moving metal sheets and objects produced, for example in a machine for cutting and/or punching metal sheets.

Since the time required to realize the desired negative pressure inside each suction cup 2 is very fast, thanks to the gripping system 100 of the invention it is necessary to supply the Venturi vacuum generators 10 of the plurality of gripping devices 1 with compressed air only for a minimal part of the process of gripping and handling the object, what allows significantly reducing (up to 90%) the consumption of compressed air and the consequent consumption of electrical energy necessary to generate the compressed air with respect to the known suction cup gripping systems.

Once the object 50 is picked up it can be lifted and/or moved safely.

If, during movement, the vacuum sensor 13 connected to the manifold 50 detects a decrease in the negative pressure or partial vacuum inside the manifold 50 and therefore inside the suction cups 2, i.e. an increase of the absolute pressure, above a second threshold value P2, for example equal to -60 kPa, the first valve 37 is switched into the open position again by the control unit 40 so as to supply compressed air coming from the supply line 30 to the Venturi vacuum generators 10 of the gripping devices 1 that start to suck air from the internal cavities 3 by placing them in negative pressure until the first threshold value Pl is reached. More precisely, if the vacuum sensor 13 detects inside the manifold 50 a relative vacuum value for example equal to -0.55 kPa, therefore lower than the second threshold value P2 equal for example to -60 kPa, the first valve 37 is switched to the open position. The second threshold value P2, for example -60 kPa, is smaller than the first threshold value Pl, for example -80 kPa, in terms of partial vacuum.

It should be noted that thanks to the adjustment nozzles 35 with calibrated hole associated with each gripping device 1 , in the event that the suction cup 2 of a gripping device 1 is not engaged with the external surface 51 of the object 50, the loss of vacuum in the manifold 50 is limited and does not compromise the regular operation of the remaining gripping devices 1 whose suction cups 2 adhere to the object 50. In fact, numerous tests carried out by the applicant have shown that the adjustment nozzles 35 minimize the suction of air by the other gripping devices 1 through the suction cup 2 not gripping.

In order that the suction cups 2 release and disengage from the object 50, the second valve 38 is activated by the control unit 40, i.e. it is electrically switched into the open position, so as to connect the release valves 11 of the gripping units 1 to the compressed air supply line 30.

The compressed air provided by the second valve 38 activates each release valve 11 by moving it to the opening position in which the internal cavity 3 of the corresponding suction cup 2 is in flow connection with the compressed air supply line 30. A blow of compressed air inside the suction cup 2 causes its immediate detachment from the external surface 51 of the object 50.

Alternatively, the release valve 11 may be switched into an open position in which it places the internal cavity 3 of the suction cup 2 into flow connection with the external environment i.e. with positive atmospheric pressure.

Thanks to the gripping system 100 of the invention it is therefore possible to significantly reduce the consumption of compressed air during operation, in particular during the gripping and moving of one or more objects included within the gripping zone defined by the plurality of gripping devices 1. In addition, it is possible to grip, hold and move objects of various sizes and weight firmly, reliably and safely.

With reference to Figure 7, a variant of the suction cup gripping system 100 of the invention is shown which differs from the embodiment described above and illustrated in Figures 5 and 6, in that it comprises a single gripping device 1 provided with a plurality of gripping suction cups 2 connected to a same Venturi vacuum generator 10 and to a same release valve 11. The gripping device 1 also comprises a check valve 12 in flow connection with, and interposed between, the Venturi vacuum generator 10 and the internal cavities 3 of the suction cups 2 and a vacuum sensor 13 in flow connection with the internal cavities 3 and suitable for measuring a value of partial vacuum inside the internal cavities. The vacuum sensor 13 is in flow connection with the internal cavities 3 of the suction cups 3 via the fourth connection 9 of the casing 4.

The gripping suction cups 2 are connected to each other and to the third connection 8 via a connecting duct 44.

The Venturi vacuum generator 10 is of the multi-stage type, and in particular comprises three stages.

The operation of this variant of the suction cup gripping system 100 of the invention is substantially equivalent to that of the gripping system described above and illustrated in Figures 5 and 6.

In particular, also in this case the plurality of suction cups 2 define a gripping zone or area which allows the gripping system 100 of the invention to pick up and move at the same time one or more objects 50 contained within said gripping zone.

With reference to Figure 8, another variant of the suction cup gripping system 100 of the invention 100 is illustrated which differs from the embodiment described above and illustrated in Figure 7 only in that the gripping device 1 comprises a single gripping suction cup 2 acting on the object 50 to be picked up and a two-stage Venturi vacuum generator 10. The operation of this other variant of the suction cup gripping system 100 of the invention is substantially equivalent to that of the gripping system described above and illustrated in Figure 7.