GRIPPING FOR VACUUM CONTAINERS

Description

[0001] The present invention relates to the field of vacuum handling.

[0002] The invention relates more particularly to a gripping member for a vacuum chamber, and a vacuum gripping device comprising such a chamber. BACKGROUND OF THE INVENTION

[0003] Vacuum gripping devices are used in many industrial sectors (automotive, pharmaceutical, etc.), for example, to move or manipulate parts on a production line. They generally consist of a vacuum chamber with a base plate (commonly called a plate) equipped with suction cups. Each suction cup comprises a metal body with a first end section fixed in a perforation in the plate and a second end section extending outside the plate and fitted with a deformable rubber skirt. The suction cups are designed to simultaneously grip a part when the air inside the chamber is drawn out by a vacuum generator.

[0004] Each specific gripping application has its own constraints. Indeed, the parts that such containers are likely to handle vary in shape, weight, and size. The containers must therefore be manufactured to meet the specific constraints in which they are used.

[0005] For obvious performance reasons, it is undesirable for one of the suction cups to not be actively gripping the part and continue to draw air while the other suction cups hold the part. Therefore, a container may not be suitable for moving an object smaller than the one for which it was designed.

[0006] Furthermore, it may not be necessary to use all the suction cups on the container to move an object lighter than the one for which it was designed. Documents FR3043005A1, US6431624B1, and US2009 / 206216A1 show examples of gripping devices. SUBJECT OF THE INVENTION

[0007] The invention therefore aims to provide a gripping device for a vacuum chamber that allows one to overcome, at least in part, the aforementioned disadvantages. SUMMARY OF THE INVENTION

[0008] For this purpose, according to the invention, a gripping device for a vacuum chamber is proposed, comprising a tubular body which has a first section delimiting a first cavity in which is mounted sliding a first hollow piston defining with the walls of the first cavity a first chamber of variable volume into which opens a compressed air conduit.

[0009] The first piston is equipped, opposite the first chamber, with a tubular extension having a free end section projecting from the first cavity and fitted with a suction cup. The first piston and the tubular extension define a suction channel with one end opening into the suction cup and an opposite end receiving a rod for a sealed sliding connection. The tubular extension has at least one first suction port to connect the suction channel to a second chamber under negative pressure.

[0010] The first piston is mounted to move in translation relative to the rod between a rest position in which the rod obstructs the first suction orifice and a gripping position in which the rod is withdrawn from the first suction orifice.

[0011] It is therefore possible to control each of the gripping devices of a vacuum chamber independently of each other and thus to adapt the number of gripping devices used for the movement of a given object.

[0012] In particular, the first piston, the tubular extension and the rod are coaxial.

[0013] In particular, the first piston is returned to its rest position by a first spring.

[0014] In particular, the tubular body includes a compressed air supply channel having one end opening into the first chamber and an opposite end opening outside the tubular body.

[0015] In particular, the tubular body includes at least one second suction port having one end opening into the second chamber and an opposite end opening outside the tubular body.

[0016] According to a particular feature of the invention, the tubular body comprises a second section defining a second cavity in which a second piston is mounted. This second piston, together with the walls of the second cavity, defines a third and a fourth chamber arranged to be connected, respectively, to the compressed air source and to ambient air. The rod is integral with the second piston and, together with said second piston, defines a delivery channel having one end opening into the suction channel and the opposite end opening into the third chamber. The second piston is mounted to move in translation between a rest position in which the rod is recessed from the suction port of the first piston in its rest position, and a disengagement position in which the rod obstructs the suction port.

[0017] In particular, the first piston and the second piston are coaxial.

[0018] In a particular way, the second piston is returned to its rest position by a second spring.

[0019] The invention also relates to a vacuum chamber equipped with at least one such gripping device.

[0020] The invention further relates to a vacuum gripping device comprising such a box. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The invention will be better understood in light of the following description, which is purely illustrative and not limiting, and should be read in conjunction with the accompanying drawings, among which: [ Fig.1 ] there figure 1 is an axial cross-sectional view of a gripping device according to a particular embodiment of the invention; [ Fig.2A ] there figure 2A is an axial cross-sectional view of the device illustrated in the figure 1 , before taking the object; [ Fig.2B ] there figure 2B is a view identical to the figure 2A , during the handling of the object; [ Fig.2C ] there figure 2C is a cross-sectional view identical to the figure 2A , during the placement of the object; [ Fig.2D ] there figure 2D is a cross-sectional view identical to the figure 2A , after the object has been placed down. DETAILED DESCRIPTION OF THE INVENTION

[0022] With reference to the figure 1 , a vacuum gripping device, generally designated as 1, comprises a vacuum chamber 10 in which a plurality of vacuum gripping devices 20 are mounted (only one of the gripping devices 20 is shown).

[0023] The enclosure 10 comprises a lower panel 11, an upper panel 12, and side panels 13 connecting the lower panel 11 to the upper panel 12 to form a sealed enclosure 14. The enclosure 14 is rectangular in shape and is intended to be connected to a vacuum generation source (not shown).

[0024] The lower panel 11 and the upper panel 12 respectively include first holes 11.1 and second holes 12.1 for receiving the gripping members 20. The first holes 11.1 and the second holes 12.1 are circular in shape, each of the second holes 12.1 extending here coaxially opposite one of the first holes 11.1. The first holes 11.1 have a diameter greater than that of the second holes 12.1.

[0025] Each gripping member 20 comprises a tubular body 21 having a central axis X substantially perpendicular to the lower panel 11 and the upper panel 12. The tubular body 21 is generally cylindrical in shape and externally comprises a shoulder 21.3 delimiting a first section 21.1 and a second section 21.2 of said tubular body 21. The first section 21.1 and the second section 21.2 are received by a tight fit into one of the first ports 11.1 and the corresponding second port 12.1, respectively. The shoulder 21.3 is in tight contact with an inner face of the upper panel 12.

[0026] The first section 21.1 extends inside the box 10 and includes a first bore 22.1 opening onto a free end of the first section 21.1. The second section 21.2 extends outside the box 10, projecting from an external face of the upper panel 12, and includes a second bore 22.2 opening onto a free end of the second section 21.2. The first bore 22.1 and the second bore 22.2 extend along the X axis and are coaxial.

[0027] The tubular body 21 also includes a third bore 22.3, coaxial with the first bore 22.1 and the second bore 22.2, connecting a bottom of said first bore 22.1 to a bottom of the second bore 22.2.

[0028] The free end of the first section 21.1 receives a retaining plate 23 in position of said first section 21.1 in the box 10. The retaining plate 23 and the first bore 22.1 together define a first cavity inside which a first piston 24 is mounted to slide along the axis X. The first piston 24 defines, with the walls of the first cavity, a first chamber C 1 and a fourth chamber C 2, both of variable volume.

[0029] The first section 21.1 includes suction ports 21.4 having one end opening into the second chamber C 2 and an opposite end opening into the box 10. The suction ports 21.4 are here symmetrically and equitably distributed around the X axis, in the same plane perpendicular to the X axis.

[0030] The tubular body 20 also includes a supply channel 21.5 for the first chamber C 1 with compressed air. The supply channel 21.5 extends along an axis substantially parallel to the X axis, and includes one end opening into the first chamber C 1 and an opposite end opening into a first compressed air supply port 27.1 provided in the plate 27. The first supply port 27.1 has one end opening into the supply channel 21.5 and an opposite end intended to be selectively connected to the compressed air source S via a first solenoid valve V 1 controlled, for example, by a PLC or an electronic board (not shown).

[0031] The first piston 24 is hollow and is provided with a tubular extension 25 which extends along the X-axis from a lower face of the first piston 24 and passes through a circular opening 23.1 in the retaining plate 23, so that a free end section of the tubular extension 25 extends outside the housing 10, projecting from an external face of the lower panel 11. The first piston 24 and the tubular extension 25 define a suction channel 25.1 extending along the X-axis. The suction channel 25.1 has one end connected to a gripping suction cup 26 which is fixed to the free end section of the tubular extension 25 via an insert 26.1.

[0032] The tubular extension 25 includes suction ports 25.2 having one end opening into the suction channel 25.1 and an opposite end opening into the second chamber C 2. The suction ports 25.2 are here symmetrically and equitably distributed around the X axis, in a plane perpendicular to the X axis.

[0033] The free end of the second section 21.2 receives a connection plate 27 for a blowing device. The plate 27 and the second bore 22.2 together define a second cavity inside which a second piston 28 is mounted to slide along the X-axis. The second piston 28, together with the walls of the second cavity, defines a third chamber C3 and a fourth chamber C4, both of variable volume.

[0034] The plate 27 includes a second compressed air supply port 27.2, one end of which opens into the third chamber C3 and the other end of which is intended to be selectively connected to a compressed air source S via a second solenoid valve V2 controlled by the PLC or the electronic board (not shown). The second section 21.2 includes a vent port 21.6, one end of which opens into the fourth chamber C4 and the other end of which opens to the outside of the housing 10.

[0035] The second piston 28 is provided with a rod 29 which extends along the axis X, from a lower face of the second piston 28, and which passes through the third bore 22.3 in a sealed manner so that a free end section of the rod 29 extends into the first bore 22.1. The free end section of the rod 29 is received by sliding sealed movement in the suction channel 25.1 delimited by the first piston 24 and the tubular extension 25.

[0036] The rod 29 is hollow and, together with the second piston 28, forms a compressed air channel 29.1. This channel has one end opening into the suction channel 25.1 and the opposite end opening into the third chamber C3 via a compressed air inlet 28.1 located on the upper face of the second piston 28. It should be noted that the inlet 28.1 has a smaller diameter than the second feed 27.2 of the plate 27, which is itself smaller than the diameter of the rod 29.1's channel. In fact, as long as one of the inlet 28.1 and the channel 29.1 has a smaller diameter than the second feed 27.2, the diameter of the other of the inlet 28.1 and the channel 29.1 is smaller. the routing is of little importance (the diameter of the routing orifice 28.1 can be equal to that of the routing channel 29.1).

[0037] The first piston 24 is mounted to slide between a high position called the rest position in which an upper face of the first piston 24 is close to the bottom of the first bore 22.1 ( figures 1 , 2A And 2D ), and a low position known as the gripping position in which the upper face of the first piston 24 is away from the bottom of the first bore 22.1 ( figures 2B And 2C ). The first piston 24 is returned to the upper position by a first helical spring R 1 surrounding the tubular extension 25. The first spring R 1 has one end bearing against an inner face of the retaining plate 23 and the lower face of the first spring R 1.

[0038] The second piston 28 is mounted to slide between a high position, called the rest position, in which the upper face of the second piston 28 is in contact with a lower face of the plate 27 ( figures 1 , 2A , 2B And 2D), and a lower position known as the removal position in which the upper face of the second piston 28 is away from the plate 27 ( figure 2C ). The second piston 28 is returned to the upper position by a second helical spring R 2 surrounding the rod 29. The second spring R 2 has one end bearing against the bottom of the second bore 22.2 and an opposite end bearing against the lower face of the second piston 28.

[0039] The free end section of rod 29 is arranged such that: when the first piston 24 and the second piston 28 are both in the top position ( figures 1 , 2A And 2D ) or in a low position ( figure 2C ), the end section of the rod 29 completely obstructs the suction ports 25.2 of the tubular extension 25 so that the suction cup 26 is not in fluidic communication with the casing 10; and when the first piston 24 is in the lower position and the second piston 28 is in the upper position ( figure 2B ), the end section of the rod 29 is set back from the suction ports 25.2 so that the suction cup 26 is in fluidic communication with the box 10.

[0040] The functioning of the grasping organ 20 will now be detailed with regard to the figures 2A à 2D .

[0041] While the first solenoid valve V1 and the second solenoid valve V2 are in the closed state, the housing 10 carrying the gripping member 20 is brought above an object P to be moved, for example via a robotic handling arm (not shown), so that the suction cup 26 of the gripping member 20 is spaced from the object P by a distance slightly less than the stroke of the first piston 24 ( figure 2A ).

[0042] The first solenoid valve V1 is then brought from the closed state to the open state so that compressed air is blown into the first chamber C1, which has the effect of moving the first piston 24 from the high position to the low position ( figure 2B ). The suction cup 26 is then in contact with an upper surface of the object P and is now in fluidic communication with the vacuum chamber 10, the end section of the rod 29 no longer obstructing the suction ports 25.2 of the tubular extension 25. It is understood that the suction cup 26 exerts a suction force on the upper surface of the object P, which generates a vacuum gripping of the object P via said suction cup 26.

[0043] It should also be noted that it is possible to measure the vacuum at the level of the second orifice 27.2 supplying the plate 27, this measurement being representative of the suction force exerted by the suction cup 26.

[0044] While the first solenoid valve V1 is held in the open state, the chamber 10 is brought via the robotic arm above the support on which the object P is to be placed, so that the object P is spaced from the support by a distance less than a predetermined distance. The second solenoid valve V2 is then brought from the closed state to the open state so that compressed air is blown into the third chamber C3, which has the effect of moving the second piston 28 from the high position to the low position ( figure 2CThe end section of the rod 29 then completely obstructs the suction ports 25.2 of the tubular extension 25, and the compressed air blown into the third chamber C3 via the second supply port 27.2 passes through the delivery channel 29.1 and arrives in the suction cup 26. It is then understood that the object P is blown away and will thus fall by gravity onto the support, the suction cup 26 no longer exerting any suction force on the object. P.

[0045] Once object P is placed on the support, the robotic arm retracts, moving suction cup 26 away from object P. While the second solenoid valve V2 remains open, the first solenoid valve V1 is closed so that, under the action of the first spring R1 and the second spring R2, the first piston 24 and the second piston 28 move approximately simultaneously from the lower to the upper position. The second solenoid valve V2 is then closed, and the gripping element 20 is once again ready for vacuum gripping.

[0046] It should be noted that: The various gripping devices 20 carried by the housing 10 can be controlled independently of each other, which makes it possible to use only part of the gripping devices 20 to move an object (in particular depending on the dimensions of the object P, its size, its weight...); the movement of the first piston 24 from the high position to the low position prevents the suction cups 26 of the unused gripping devices 20 from coming into contact with the object P to be handled; the movement of the second piston 28 from the high position to the low position allows for the selective and asynchronous placement of objects P; and the first spring R 1 and the second spring R 2 respectively ensure the return of the first piston 24 and the second piston 28 while maintaining the supply of compressed air to the suction cup 26 in order to limit the risk of self-aspiration by the suction cup 26 when the robotic arm cannot ensure a withdrawal movement after the placement of the object P.

[0047] Of course, the invention is not limited to the embodiments described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0048] The housing 10 may only carry a single gripping device 20.

[0049] The first solenoid valve V 1 and the second solenoid valve V 2 can be replaced by any device allowing the first supply port 27.1 and the second supply port 23.2 to be selectively connected to the compressed air source S.

[0050] The first supply port 27.1 and the second supply port 27.2 of the plate 27 can be connected to separate compressed air sources.

[0051] The second piston 28 is optional. The rod 29 is then fixed relative to the tubular body 20, and the object P is deposited solely by gravity once the suction cup 26 is no longer in fluidic communication with the vacuum chamber 10, that is, when the first solenoid valve V1 is moved from the open to the closed state. If it is necessary to inject compressed air into the suction cup 26 to deposit the object P, a reversing valve can be mounted on the vacuum generator connected to the chamber 10 to alternate between vacuum and pressure in the enclosure 14 of said chamber 10.

[0052] A non-return valve can be added to the second piston 28 to prevent compressed air from entering the enclosure 14 of the box 10 when the second solenoid valve V 2 changes from the closed state to the open state.

Claims

1. Grip member (20) for a vacuum box, comprising a tubular body (21) which comprises a first section (21.1) delimiting a first cavity in which a first hollow piston (24) is slidingly mounted, defining with walls of the first cavity, a first chamber (C1) of variable volume, into which a compressed air conduit (S) opens, the first piston being provided, opposite the first chamber, with a tubular extension (25) having a free end section projecting from the first cavity and provided with a suction cup, the first piston and the tubular extension defining a suction channel (25.1) having an end which opens into the suction cup (26) and an opposite end which slidingly, sealingly receives a rod (29), the tubular extension comprising at least one first suction orifice (25.2) to connect the suction channel to a second chamber (C2) under negative pressure and the first piston being movably mounted in translation with respect to the rod between a rest position in which the rod blocks the first suction orifice and a gripping position in which the rod is recessed from the first suction orifice.

2. Grip member (20) according to claim 1, wherein the first piston (24), the tubular extension (25) and the rod (29) are coaxial.

3. Grip member (20) according to any one of the preceding claims, wherein the first piston (24) is returned to its rest position by a first spring (R1).

4. Grip member (20) according to any one of the preceding claims, wherein the tubular body (21) comprises a compressed air supply channel (21.5) having an end opening into the first chamber (C1) and an opposite end opening to the outside of the tubular body (21).

5. Grip member (20) according to any one of the preceding claims, wherein the tubular body (21) comprises at least one second suction orifice (21.4) having an end opening into the second chamber (C2) and an opposite end opening to the outside of the tubular body (21).

6. Grip member (20) according to any one of the preceding claims, wherein the tubular body comprises a second section (21.2) delimiting a second cavity in which a second piston (28) is mounted, defining with walls of the second cavity, a third chamber (C3) and a fourth chamber (C4) arranged to be connected respectively to the compressed air source (S) and to the ambient air, the rod being secured to the second piston and defining with said second piston, a delivery channel (29.1) having an end opening into the suction channel (25.1) and an opposite end opening into the third chamber (C3), and the second piston being movably mounted in translation between a rest position in which the rod is recessed from the suction orifice of the first piston in the rest position, and a deposition position in which the rod blocks the suction orifice.

7. Grip member (20) according to claim 6, wherein the first piston (24) and the second piston (28) are coaxial.

8. Grip member (20) according to claim 6 or 7, wherein the second piston (28) is returned to its rest position by a second spring (R2).

9. Vacuum box (10) equipped with a grip member (20) according to any one of the preceding claims.

10. Device for gripping by vacuum (1) comprising a box (10) according to claim 9.