Gripping device for vacuum box

Abstract

Gripping member (20) for a vacuum chamber, comprising a tubular body (21) which comprises a section (21.1) delimiting a cavity in which is slidably mounted a hollow piston (24) defining with walls of the first cavity a first chamber (C1) of variable volume into which a compressed air conduit (S) opens, the 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 piston and the tubular extension defining a suction channel (25.1) having one end which opens into the suction cup (26) and an opposite end which receives a rod (29) in a sealed sliding manner, the tubular extension comprising at least one suction orifice (25.2) to connect the suction channel to a second chamber (C2) in depression, and the piston being mounted movable in translation relative to the rod between a rest position in which the rod obstructs the suction orifice and a gripping position in which the rod is set back from the suction orifice. FIGURE OF THE ABSTRACT: Fig.1.

Description

Title of the invention: Gripping member for vacuum box

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

[0002] The invention relates more particularly to a gripping member for a box with vacuum, and a vacuum gripping device comprising such a box.

[0003] BACKGROUND OF THE INVENTION

[0004] Vacuum gripping devices are used in many industrial fields (automotive, pharmaceutical, etc.), for example to move or handle parts in a production line. They generally comprise a vacuum box comprising a lower panel (commonly called a base) provided with suction cups. Each suction cup comprises a metal body having a first end section fixed in a perforation of the plate and a second end section extending outside the plate and carrying a deformable rubber skirt. The suction cups are intended to simultaneously grip a part when the air contained inside the box is sucked out by means of a vacuum generator.

[0005] Each particular gripping application has its own constraints. Indeed, the parts that such boxes are likely to handle are of variable shape, weight and size. The boxes must therefore be manufactured in such a way as to meet the particular constraints in which they are used.

[0006] For obvious performance reasons, it is not desirable for one of the suction cups not to participate in gripping the part and to continue to suck air while the other suction cups hold the part. Thus, a box may not be suitable for moving an object of a smaller size than that for which it was sized.

[0007] Furthermore, it may not be necessary to use all of the suction cups in the box to move an object lighter than that for which it was designed.

[0008] SUBJECT OF THE INVENTION

[0009] The object of the invention is therefore to propose a gripping member for a vacuum box making it possible to at least partially overcome the aforementioned drawbacks. Summary of the invention

[0010] To this end, the invention proposes a gripping member for a vacuum box, comprising a tubular body which has a first section delimiting a first cavity in which is slidably mounted a first hollow piston defining with walls of the first cavity a first chamber of variable volume into which a compressed air conduit opens.

[0011] The first piston is provided, opposite the first chamber, with a tubular extension having a free end section projecting from the first cavity and provided with a suction cup. The first piston and the tubular extension define a suction channel having one end which opens into the suction cup and an opposite end which receives a rod in a sealed sliding manner. The tubular extension comprises at least a first suction orifice for connecting the suction channel to a second chamber under vacuum.

[0012] 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 set back from the first suction orifice.

[0013] It is thus possible to control each of the gripping members of a vacuum box independently of one another and therefore to adapt the number of gripping members used for the movement of an object in question.

[0014] In particular, the first piston, the tubular extension and the rod are coaxial.

[0015] In particular, the first piston is returned to its rest position by a first spring.

[0016] In particular, the tubular body comprises a compressed air supply channel having one end opening into the first chamber and an opposite end opening outside the tubular body.

[0017] In particular, the tubular body comprises at least one second suction orifice having one end opening into the second chamber and an opposite end opening outside the tubular body.

[0018] According to a particular characteristic of the invention, the tubular body comprises a second section delimiting a second cavity in which is mounted a second piston defining with walls of the second cavity a third chamber and a fourth chamber arranged to be connected respectively to the compressed air source and to the ambient air. The rod is integral with the second piston and defines with said second piston a conveying channel having one end opening into the suction channel and an opposite end opening into the third chamber. The second piston is mounted movable in translation between a rest position in which the rod is set back from the suction orifice of the first piston in the rest position, and a deposited position in which the rod obstructs the suction orifice.

[0019] In particular, the first piston and the second piston are coaxial.

[0020] In particular, the second piston is returned to its rest position by a second spring.

[0021] The invention also relates to a vacuum box equipped with at least one such gripping member.

[0022] The invention further relates to a vacuum gripping device comprising such a box. Brief description of the drawings

[0023] The invention will be better understood in light of the following description, which is purely illustrative and non-limiting, and must be read in conjunction with the appended drawings, among which:

[0024] [Fig-1] [Fig.l] is an axial sectional view of a gripping device according to a particular embodiment of the invention;

[0025] [Fig.2A] [Fig.2A] is an axial sectional view of the device illustrated in [Fig.l], before the object is picked up;

[0026] [Fig.2B] [Fig.2B] is a view identical to [Fig.2A], during the taking of the object;

[0027] [Fig.2C] [Fig.2C] is a sectional view identical to [Fig.2A], during removal of the object;

[0028] [Fig.2D] [Fig.2D] is a sectional view identical to [Fig.2A], after removal of the object. DETAILED DESCRIPTION OF THE INVENTION

[0029] Referring to [Fig.l], a vacuum gripping device, generally designated 1, comprises a vacuum box 10 in which a plurality of vacuum gripping members 20 are mounted (only one of the gripping members 20 is shown).

[0030] The box 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 here has the shape of a rectangular parallelepiped and is intended to be connected to a vacuum generation source (not shown).

[0031] The lower panel 11 and the upper panel 12 respectively comprise first orifices 11.1 and second orifices 12.1 for receiving the gripping members 20. The first orifices 11.1 and the second orifices 12.1 are circular in shape, each of the second orifices 12.1 extending here coaxially opposite one of the first orifices 11.1. The first orifices 11.1 here have a diameter greater than that of the second orifices 12.1.

[0032] Each of the gripping members 20 comprises a tubular body 21 having a central axis X substantially perpendicular to the lower panel 11 and to 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 with adjustment respectively in one of the first orifices 11.1 and in the corresponding second orifice 12.1. The shoulder 21.3 is in sealed contact with an internal face of the upper panel 12.

[0033] The first section 21.1 extends inside the box 10 and comprises 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 comprises 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.

[0034] The tubular body 21 also comprises a third bore 22.3, coaxial with the first bore 22.1 and with the second bore 22.2, connecting a bottom of said first bore 22.1 to a bottom of the second bore 22.2.

[0035] The free end of the first section 21.1 receives a holding plate 23 in position of said first section 21.1 in the box 10. The holding plate 23 and the first bore 22.1 together define a first cavity inside which a first piston 24 is slidably mounted along the axis X. The first piston 24 defines, with the walls of the first cavity, a first chamber Ci and a fourth chamber C2, both of variable volume.

[0036] The first section 21.1 comprises suction orifices 21.4 having one end opening into the second chamber C2 and an opposite end opening into the box 10. The suction orifices 21.4 are here symmetrically and equally distributed around the axis X, in the same plane perpendicular to the axis X.

[0037] The tubular body 20 also comprises a channel 21.5 for supplying the first chamber Ci with compressed air. The supply channel 21.5 extends along an axis substantially parallel to the axis X, and comprises one end opening into the first chamber Ci and an opposite end opening into a first compressed air supply orifice 27.1 formed in the plate 27. The first supply orifice 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 Vi controlled, for example, by an automaton or an electronic card (not shown).

[0038] The first piston 24 is hollow and is provided with a tubular extension 25 which extends along the axis X from a lower face of the first piston 24 and which passes in a sealed manner through a circular opening 23.1 formed in the retaining plate 23, so that a free end section of the tubular extension 25 extends outside the box 10, projecting from an external face of the lower panel 11. The first piston 24 and the tubular extension 25 delimit 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.

[0039] The tubular extension 25 comprises suction orifices 25.2 having one end opening into the suction channel 25.1 and an opposite end opening into the second chamber C2. The suction orifices 25.2 are here symmetrically and equally distributed around the axis X, in a plane perpendicular to the axis X.

[0040] The free end of the second section 21.2 receives a plate 27 for connection to 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 axis X. The second piston 28 defines, with the walls of the second cavity, a third chamber C3 and a fourth chamber C4, both of variable volume.

[0041] The plate 27 comprises a second compressed air supply orifice 27.2 having one end opening into the third chamber C3 and an opposite end intended to be selectively connected to a compressed air source S via a second solenoid valve V2 controlled by the controller or the electronic card (not shown). The second section 21.2 comprises a vent orifice 21.6 having one end opening into the fourth chamber C4 and an opposite end opening outside the box 10.

[0042] 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 in a sealed manner through the third bore 22.3 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 in a sealed sliding manner in the suction channel 25.1 delimited by the first piston 24 and the tubular extension 25.

[0043] The rod 29 is hollow and delimits with the second piston 28 a compressed air conveying channel 29.1 having one end opening into the suction channel 25.1 and an opposite end opening into the third chamber C3 via a compressed air conveying orifice 28.1 provided on an upper face of the second piston 28. It will be noted that the conveying orifice 28.1 has a diameter smaller than that of the second supply orifice 27.2 of the plate 27, which is itself smaller than that of the conveying channel 29.1 of the rod 29. In fact, as long as one of the conveying orifice 28.1 and the conveying channel 29.1 has a diameter smaller than that of the second supply orifice 27.2, the diameter of the other of the conveying orifice 28.1 and from channel 29.1 of import routing little (the diameter of the routing orifice 28.1 may be equal to that of the routing channel 29.1).

[0044] The first piston 24 is slidably mounted between a high position called rest in which an upper face of the first piston 24 is close to the bottom of the first bore 22.1 (FIGS. 1, 2A and 2D), and a low position called gripping in which the upper face of the first piston 24 is distant from the bottom of the first bore 22.1 (FIGS. 2B and 2C). The first piston 24 is returned to the high position by a first helical spring Ri surrounding the tubular extension 25. The first spring Ri has one end bearing against an internal face of the holding plate 23 and the lower face of the first spring Rb

[0045] The second piston 28 is slidably mounted between a high position called rest in which the upper face of the second piston 28 is in contact with a lower face of the plate 27 (FIGS. 1, 2A, 2B and 2D), and a low position called deposit in which the upper face of the second piston 28 is distant from the plate 27 ([Fig. 2C]). The second piston 28 is returned to the high position by a second helical spring R2 surrounding the rod 29. The second spring R2 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.

[0046] The free end section of the rod 29 is arranged so that: - when the first piston 24 and the second piston 28 are both in the high position (figures 1, 2A and 2D) or in the low position ([Fig.2C]), the end section of the rod 29 completely obstructs the suction orifices 25.2 of the tubular extension 25 so that the suction cup 26 is not in fluid communication with the box 10; and - when the first piston 24 is in the low position and the second piston 28 in the high position ([Fig.2B]), the end section of the rod 29 is set back from the suction orifices 25.2 so that the suction cup 26 is in fluid communication with the box 10.

[0047] The operation of the gripping member 20 will now be detailed with reference to FIGS. 2A to 2D.

[0048] While the first solenoid valve Vi and the second solenoid valve V2 are in the closed state, the box 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 ([Fig.2A]).

[0049] The first solenoid valve Vj is then brought from the closed state to the open state so that compressed air is blown into the first chamber Ci, which has the following effect: effect of moving the first piston 24 from the high position to the low position ([Fig.2B]). The suction cup 26 then rests against an upper surface of the object P and is now in fluid communication with the vacuum box 10, the end section of the rod 29 no longer obstructing the suction orifices 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 causes a gripping by the vacuum of the object P via said suction cup 26.

[0050] It will also be noted that it is possible to measure the vacuum at the second supply orifice 27.2 of the plate 27, this measurement being representative of the suction force exerted by the suction cup 26.

[0051] While the first solenoid valve Vj is kept in the open state, the box 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 ([Fig.2C]). The end section of the rod 29 then completely obstructs the suction orifices 25.2 of the tubular extension 25, and the compressed air blown into the third chamber C3 via the second supply orifice 27.2 passes through the conveying channel 29.1 and arrives in the suction cup 26.We then understand that the object P is blown and that it will thus fall by gravity onto the support, the suction cup 26 then no longer exerting any suction force on the object P.

[0052] Once the object P has been placed on the support, the robotic arm performs a withdrawal movement allowing the suction cup 26 to be moved away from the object P. While the second solenoid valve V2 is maintained in the open state, the first solenoid valve Vj is brought from the open state to the closed state so that, under the action of the first spring Ri and the second spring R2, the first piston 24 and the second piston 28 pass substantially simultaneously from the low position to the high position. The second solenoid valve V2 is finally brought from the open state to the closed state, the gripping member 20 being again ready for a new gripping by the vacuum.

[0053] It should be noted that: - the various gripping members 20 carried by the box 10 can be controlled independently of one another, which makes it possible to use only part of the gripping members 20 to move an object (in particular depending on the dimensions of the object P, its size, its weight, etc.); - the passage of the first piston 24 from the high position to the low position makes it possible to prevent the suction cups 26 of the unused gripping members 20 from coming into contact with the object P to be handled; - the passage of the second piston 28 from the high position to the low position allows the selective and asynchronous removal of objects P; and - the first spring Ri and the second spring R2 respectively ensure the rise of the first piston 24 and the second piston 28 while maintaining the insufflation of compressed air into 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 removal of the object P.

[0054] 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.

[0055] The box 10 may carry only a single gripping member 20.

[0056] The first solenoid valve Vj and the second solenoid valve V2 can be replaced by any device making it possible to selectively connect the first supply port 27.1 and the second supply port 23.2 to the compressed air source S.

[0057] 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.

[0058] The second piston 28 is optional. The rod 29 is then fixed relative to the tubular body 20 and the object P is then removed solely by gravity when the suction cup 26 is no longer in fluid communication with the vacuum box 10, i.e. when the first solenoid valve Vj is brought from the open state to the closed state. In the case where it is necessary to blow compressed air into the suction cup 26 to remove the object P, a reversing valve can be mounted on the vacuum generator connected to the box 10 in order to alternate vacuum and pressure in the enclosure 14 of said box 10.

[0059] A non-return valve may be added to the second piston 28 in order to prevent compressed air from entering the enclosure 14 of the box 10 when the second solenoid valve V2 changes from the closed state to the open state.

Claims

Claims

1. Gripping member (20) for a vacuum chamber, comprising a tubular body (21) which comprises a first section (21.1) delimiting a first cavity in which is slidably mounted a first hollow piston (24) defining with walls of the first cavity a first chamber (Ci) 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 one end which opens into the suction cup (26) and an opposite end which receives a rod (29) in a sealed sliding manner, the tubular extension comprising at least one first suction orifice (25.2) to connect the suction channel to a second chamber (C2) under vacuum, and the first piston being 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 set back from the first suction orifice.

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

3. Gripping member (20) according to any one of the preceding claims, in which the first piston (24) is returned to its rest position by a first spring (Ri).

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

5. Gripping 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 one end opening into the second chamber (C2) and an opposite end opening outside the tubular body (21).

6. Gripping member (20) according to any one of the preceding claims, in which the tubular body comprises a second section (21.2) delimiting a second cavity in which is mounted a second piston (28) 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 integral with the second piston and defining with said second piston a conveying channel (29.1) having one end opening into the suction channel (25.1) and an opposite end opening into the third chamber (C3), and the second piston being mounted movable in translation between a rest position in which the rod is set back from the suction orifice of the first piston in the rest position, and a deposited position in which the rod obstructs the suction orifice.

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

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

9. Vacuum box (10) equipped with at least one gripping member (20) according to any one of the preceding claims.

10. A vacuum gripping device (1) comprising a box (10) according to claim 9.

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