EP0007844B1 - Vacuum type load handling device - Google Patents

Description

The present invention relates to a suction cup gripping device.

Vacuum gripping devices have been known and used for a long time; the suction cup consists of a skirt, made of a deformable material such as rubber, which is applied to a surface of the part that is to be taken using the suction cup, said skirt delimiting between itself and the surface of the room an escape in which we create a depression. Thanks to this depression the suction cup adheres more or less strongly to said surface and the part can be manipulated through this suction cup.

British patent 1,036,586 describes an improved device of the suction cup type comprising a skirt constituted by a deformable toric pocket which may contain a granular material.

A process for handling products which may be in the form of particles has also been described in United States patent 3,040,920, this process consisting in surrounding all of these particles using with a flexible film and create a vacuum in the pocket thus created, in order to freeze said particles. The freezing operation according to the patent of the United States of America has the effect of ensuring that all of said particles trapped in the flexible film behaves like a rigid object.

The difficulties encountered in the use of suction cups come essentially from skirts which adapt more or less well to the surface of the part to be grasped: the present invention therefore relates to an improved skirt for suction cup and the suction cup itself using said skirt.

The present invention therefore relates to a suction-type gripping device comprising a skirt constituted by a deformable pocket of generally toric shape containing particles, this pocket being intended to match the surface of objects to be handled, characterized in that the particles contained in said pocket are made up, on the one hand, of dense particles and, on the other hand, of light particles and that the device is provided with a means making it possible to produce a vacuum inside the pocket in order to achieve a freezing said particles and a means making it possible to produce a certain depression in the space situated between the surface of the part to be grasped and said skirt.

The toroidal elastic pocket which constitutes the skirt and which contains the particles can form a single cavity or can be split radially into several distinct chambers; said fractionation generally allows a more constant distribution of the particles inside the pocket.

• - la réalisation d'une dépression, par rapport à la pression extérieure, dans la poche;
• - l'emploi de particules magnétiques figées à l'aide d'un champ magnétique;
• - une modification d'état d'un matériau présent sur lesdites particules comme par exemple la solidification de l'eau imbibant des particules de sable et des combinaisons de ces moyens.

Among the means making it possible to ensure the freezing of the particles one can mention:

• - The achievement of a depression, relative to the external pressure, in the pocket;
• - the use of magnetic particles frozen using a magnetic field;
• - A change in the state of a material present on said particles such as, for example, the solidification of water soaking in sand particles and combinations of these means.

But the preferred means of freezing is the achievement of a depression.

The suction cup according to the invention, using said skirt, is characterized in that it comprises, in addition to said skirt, means allowing a certain depression in the space situated between the surface of the part to be apprehended on which said skirt is applied and said skirt.

Thus, according to the invention, it is possible to produce a depression inside the skirt with a view to freezing the particles contained therein and a depression in the space situated between the surface of the part to be apprehended and said skirt. These two depressions can be the same or different and can be performed simultaneously or with a certain time lag. It is considered desirable to first produce a suitable depression inside the skirt and then the depression in the space mentioned above.

The invention will be better understood by referring to the single drawing which represents in section an embodiment, without limitation, of the gripping device according to the invention.

• - en 1 une plaque rigide;
• - en 2 une autre plaque rigide pouvant être serrée sur la plaque 1 de façon à coincer entre 1 et 2 les bords d'une ouverture pratiquée dans une sphère vide en caoutchouc 3;
• - les bords d'une autre ouverture pratiquée dans la même sphère en caoutchouc, à l'opposé de la première ouverture, sont coincés entre deux autre plaques rigides 4 et 5; les deux plaques 4 et 5 sont fixées sur la plaque 2 de façon à laisser subsister, entre les faces en regard de 4 et de 2, un passage de hauteur 1 à 3 mm environ;
• - de cette façon la sphère de caoutchouc initiale prend la forme d'une jupe de forme sensiblement torique; dans cette jupe (entre les deux parois de caoutchouc) on dispose un remplissage à l'aide de particules 9; ces particules peuvent êtres quelconques comme par exemple des billes de matière plastique; on emploiera de préférence une certaine quantité de billes de plomb qui lesteront le dispositif et favoriseront un certain étalement du dispositif au contact de la surface de la pièce à appréhender et, pour le reste du volume intérieur, des billes de polystyrène expansé; c'est ce mode de réalisation qui est représenté sur la figure unique;
• - les plaques 1, 2, 3 et 4 sont percées en leur centre d'une ouverture avec un tube 6 qui est relié à un groupe soufflant susceptible, à volonté, soit de fournir une certaine pression au-dessus de la pression atmosphérique, soit de fournir une certaine dépression; ledit group soufflant (non représenté sur la figure) est donc en liaison, par le tube 6, d'une part, avec l'intérieur de la poche torique 3 par l'intermédiaire du passage entre les plaques 2 et 4 et, d'autre part, avec l'espace 7 qui est ménagé, par le dispositif selon l'invention, entre lui-même et la surface de la pièce à appréhender (représenté schématiquement en 8).

This figure represents:

• - in 1 a rigid plate;
• - in 2 another rigid plate which can be clamped on the plate 1 so as to wedge between 1 and 2 the edges of an opening made in an empty rubber sphere 3;
• - The edges of another opening made in the same rubber sphere, opposite the first opening, are wedged between two other rigid plates 4 and 5; the two plates 4 and 5 are fixed to the plate 2 so as to allow a passage of height 1 to 3 mm approximately to remain between the opposite faces of 4 and 2;
• - in this way the initial rubber sphere takes the form of a skirt of substantially toroidal shape; in this skirt (between the two rubber walls) there is a filling using particles 9; these particles can be any, such as, for example, plastic balls; preferably use a certain quantity of lead balls which will ballast the device and promote a certain spreading of the device in contact with the surface of the part to be grasped and, for the rest of the interior volume, expanded polystyrene balls; it is this mode of embodiment which is shown in the single figure;
• - The plates 1, 2, 3 and 4 are pierced in their center with an opening with a tube 6 which is connected to a blowing group capable, at will, of either supplying a certain pressure above atmospheric pressure, or to provide some depression; said blowing group (not shown in the figure) is therefore connected, by the tube 6, on the one hand, with the interior of the toric bag 3 via the passage between the plates 2 and 4 and, on the other hand, with the space 7 which is provided, by the device according to the invention, between itself and the surface of the part to be apprehended (shown diagrammatically at 8).

• - le dispositif est amené au contact avec la surface de la pièce à saisir;
• - au moyen du groupe soufflant, on insuffle une légère pression à l'intérieur de la poche torique et de l'espace entre l'appareil et la pièce, tout en maintenant le contact, de façon à favoriser l'étalement de la poche torique sur la surface de la pièce à saisir; on remarquera que cette opération, bien que souvent souhaitable, peut être supprimée dans de nombreux essais;
• - puis on inverse le fonctionnement du groupe soufflant qui devient ainsi un groupe aspirant; ce groupe crée une certaine dépression, par rapport à la pression atmosphérique, dans la poche torique ce qui a pour résultat une mise en contact très étroite de la poche avec la surface de la pièce à saisir et dans l'espace situé entre la surface de la pièce et l'appareil;
• - on peut alors soulever ladite pièce avec ledit appareil.

The operation of the device according to the invention can be described as follows:

• - The device is brought into contact with the surface of the part to be gripped;
• - by means of the blowing group, a slight pressure is blown inside the toric pocket and the space between the device and the part, while maintaining contact, so as to promote spreading of the toric pocket on the surface of the part to be gripped; it will be noted that this operation, although often desirable, can be eliminated in numerous tests;
• - Then the operation of the blowing group is reversed, which thus becomes an suction group; this group creates a certain depression, relative to atmospheric pressure, in the toroidal pocket which results in a very close contact of the pocket with the surface of the part to be grasped and in the space located between the surface of the room and the appliance;
• - we can then lift said part with said device.

The device described above and its mode of operation are in no way limitative of the invention; it is indeed possible to produce the toroidal pocket by numerous equivalent means; the essence of the invention resides in the fact that the device has the general shape of a suction cup, that the gripping force exerted essentially comes from the pressure difference created in the space between the skirt of this suction cup and the surface of the part by means of a vacuum device and that the skirt of this suction cup is constituted by a pocket-of generally toric shape having a flexible wall, filled with suitable particles, pocket in which it is possible to achieve a certain depression by relation to the atmosphere and possibly some overpressure if necessary.

The device according to the invention can preferably be used with air as the fluid, but it can also be used with other fluids, for example liquids.

For gripping and transporting large parts, it will be possible to use several devices according to the invention connected for example to the same blowing group and which can be suitably positioned on said parts by any known device.

Claims (4)

1. Gripping device of the suction type comprising a skirt constituted by a deformable pocket (3) of overall annular shape containing particles (9), said pocket being designed to adopt the surface of objects (8) to be handled, characterised in that the particles (9) contained in the said pocket (3) are constituted on the one hand of dense particles and on the other hand of light particles and the device is provided with means (6-2-4) permitting to create a depression inside the pocket (3) in order to congeal the said particles (9) and means (6) permitting to create a certain depressure in the space (7) situated between the surface of the part (8) to be gripped and the said skirt.

2. Device according to claim 1, characterised in that the means for creating the depression inside the pocket (3) and the means for creating the depression in the space situated between the surface of the part (8) to be gripped and the skirt are constituted by a suction pump.

3. Device according to claim 2, characterised in that the communication between the means for creating a depression inside the pocket (3) and the inside of the said pocket (3) is constituted by a space provided between two parallel plates (1-2), (4,5) between which are secured the walls of the pocket.

4. Device according to one of claims 1, 2 and 3 characterised in that the dense particles are made of lead and the light particles are in expanded polystyrene.

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