EP1118578A1 - Suction gripper - Google Patents

Abstract

The handling head for timber planks has a casing (1) wit a sole plate (2) having suction openings (3). The sole plate has a deformable panel (8) have piercings opposite the openings extending through the panel and having cavities (10) openings on the lower face of the panel. The cavities have walls angled toward a respective piercing (9) into the cavity. The cavities can be centered on the piercings.

Description

The present invention relates to a head gripping by suction.

We know gripping systems and transport of materials such as boards, plates of sheets or the like. These systems include a structure mounted movable along a chassis and comprising a gripping head by aspiration.

In known systems, the gripping heads by suction include a box connected to a device suction, generally a turbine, carried by the system chassis. The gripping head box has a sole supporting rows of independent compartments each comprising an opening suction opening on the underside of the sole. The document US-A-1 514 036 describes in particular a gripping member using a rigid plate to which a rubber plate is attached having a peripheral lip forming a suction cup. This device does not allow objects to be lifted not completely covering the perimeter of the lip.

Likewise, document US-A-4 852 926 describes a suction gripper using a layer of rubber foam sandwiched between two pierced rigid plates, the bottom plate being smaller dimension than the top plate so that the tightening of the two plates forms in the rubber foam a cavity delimited by a lip in edge of the foam layer. As in the document above, sealing is only obtained if the object to lift extends beyond the edge of the bottom plate. As it has an important dimension, no effect adaptation to narrow articles cannot be got. No search for such an adaptation is moreover mentioned in this document.

In order to ensure a good seal between the sole and articles seized by the gripping head, It is known from document FR-A-2,495,592 to equip the sole of a sheet of cellular material comprising holes opposite the suction holes of the soleplate of the box. In order to ensure a depression on a sufficient area to allow lifting of articles seized by the gripping head, the holes described in this document are shaped like lights oblong arranged side by side in rows. We provides in this document to make the material plate alveolar in an open cell structure or partially closed and to cover the side wall of drilling with a semi-permeable membrane avoiding excessive great loss of suction.

A head of this type is satisfactory for the gripping articles with a large area of contact with the gripping head but raises problems with gripping items with at least a dimension of small importance, for example for the gripping sticks or for gripping pieces of short length of wood, which can then appear at an angle to the holes in the material plate alveolar, so the holes that are insufficiently covered cannot be placed depression and therefore do not participate in gripping the article. In addition, the installation of a semi-permeable membrane on the wall of the oblong lights is a delicate operation which significantly increases the cost of a gripping head in accordance with this document.

According to the invention there is provided a gripping head by suction comprising a box having a sole pierced with suction ports, this sole being equipped a plate of deformable material having opposite suction holes of the holes passing through the plate and associated with cavities opening on one side bottom of the plate, each cavity having walls deformable inclined towards a hole opening into the cavity, characterized in that the cavities are formed in the thickness of the plate of deformable material and in that the deformable walls extend close immediate drilling.

Thus, when entering an article, it suffices lower the gripping head to cause a local crushing of the deformable material until a sufficient contact is obtained with the inclined walls of the cavity to ensure a tight closure thereof. Aspiration then causes a depression of a surface which is a function of the degree of penetration of the material deformable. It is thus possible to ensure an implementation depression of a large area while achieving small holes in the material plate deformable.

According to an advantageous version of the invention, the holes in the plate of deformable material include rigid inserts. This avoids a decrease in the hole passage section during installation corresponding cavity depression and so it's possible to further reduce the size of the holes, this which improves the performance of the gripping head in reducing the flow required for its operation and minimizing the number of cavities that cannot be tightly closed, especially on the edge of a article.

• la figure 1 est une vue de dessous d'une partie d'une tête de préhension selon l'invention,
• la figure 2 est une vue en coupe agrandie selon la ligne II-II de la figure 1,
• la figure 3 est une vue en coupe analogue à celle de la figure 2 d'une cavité selon une première variante de réalisation de l'invention,
• la figure 4 est une vue en coupe analogue à celle de la figure 2 d'une cavité selon une seconde variante de réalisation de l'invention.

Other characteristics and advantages of the invention will appear on reading the following description of a preferred non-limiting embodiment of the invention, in relation to the attached figures among which:

• FIG. 1 is a bottom view of part of a gripping head according to the invention,
• FIG. 2 is an enlarged sectional view along the line II-II of FIG. 1,
• FIG. 3 is a sectional view similar to that of FIG. 2 of a cavity according to a first alternative embodiment of the invention,
• Figure 4 is a sectional view similar to that of Figure 2 of a cavity according to a second embodiment of the invention.

Referring to Figures 1 and 2, the head of gripping according to the invention comprises in a manner known in itself a box 1 having a sole 2 pierced with orifices 3 associated with compartments 4 connected to suction collectors 5 through upper ports 6 compartments 4, upper openings 6 can be closed by valves 7 when the compartments 4 are depressed while no article is present in look at the corresponding suction ports 3.

According to the invention, the gripping head comprises a plate of deformable material 8, here a plate of foam material such as foam material plastic or foam rubber, having holes 9 which pass through the plate 8 opposite the suction ports 3 of the sole 2 of the box and which are associated with cavities 10. The cavities 10 open onto the underside of the material plate alveolar and have walls 11 which are inclined towards the drilling 9 opening into the corresponding cavity. In the particular embodiment illustrated in FIG. 1, in the absence of objects seized the cavities 10 have an edge delimiting a rectangular perimeter and the walls inclined cavities are substantially flat and form with a horizontal plane an angle of about 10 °. The walls inclined 11 intersect along lines of intersection 12 which converge towards the holes 9 but are preferably not intersecting at the edge of the hole 9 in order to achieve radial conduits around the corresponding corresponding hole 9 when the sheet of cellular material 2 is strongly crushed opposite a hole 9. These radial conduits are particularly useful when the cavity walls are very slightly inclined with respect to a horizontal plane, and can also be made in the form of grooves in the walls of the cavities or on the contrary in the form of projecting ribs locally reducing the deformation of Wall. These radial conduits help maintain diffusion depression an area as large as possible of the article part covered by the part corresponding to a cavity. To avoid a reduction of the passage section of the holes 9 during the setting depression of a cavity 10, the holes 9 are preferably fitted with rigid inserts 13, for example rigid plastic tube sections.

To minimize wear on the material plate alveolar, or to modify its permeability in the case of open or semi-closed cell foam, you can advantageously provide that it is equipped with a skin 14 on its underside. However, it should note that the skin 14 decreases the flexibility of the material alveolar and its ability to follow the contours of roughness of the surface of the articles to be grasped. The skin 14 should therefore preferably be made of a very flexible. This skin can be waterproof or semi-permeable and cover all or part of the walls of the cavities. She can be obtained by simple projection or application of a product on the walls of the cavities 10. In the case of a sheet of cellular material made by molding the skin can also be obtained directly during molding by appropriate treatment of the plate surface.

When using the gripping head according to the invention, it is gradually lowered to articles to grab. The underside of the plate of foam material 8 first comes into contact with the upper surface of the articles to be grasped at the level of zones 15 which separate the cavities 10. Given the low importance of these areas, it is easy to carry out a crushing of the cellular material constituting the plate 8 even if it is a closed cell material. This overwriting is performed until the edges the surface of the article to be grasped contact with the walls of the cavities 10 so that the cavities 10 corresponding are sealed off by article 16 to be lifted, here a wooden board. This thus allows to lift articles having dimensions weaker than the periphery of the cavities 10. We observe then (see figure 2) that the surface of the article 16 put under vacuum is a function of the crushing of the material alveolar constituting the plate 8. To obtain a large surface depressed, so it is desirable to make as small a crushing of the sheet of cellular material 8. However, when article presents itself across a cavity it is necessary to ensure sufficient crushing of the material alveolar so that the part of the cavity containing the orifice suction 3 is sealed. The choice of cellular material as well as the shape of the cavities, the profile of the walls and the inclination of these will therefore chosen according to the items to be lifted. In particular in the case of boards or elongated articles, it is better to realize cavities whose edge delimits a rectangular periphery as illustrated in figure 1. For manufacturing reasons we can provide a perimeter with rounded corners. In the case of articles of dimensions more balanced, for example in the case of gripping square or disc-shaped items, preferably use a gripping head comprising cavities having an edge delimiting a polygonal periphery regular or circular.

Similarly, the optimum profile of the walls 11 of the cavities depends on the shape and surface condition of the items to grab. As an example of the walls 11 having a convex curvilinear profile as illustrated by Figure 3 ensure good sealing with small items or arranged in a way transverse to the cavity due to the low crushing which is necessary to close a cavity 10 of waterproof regardless of size or orientation of the article. However, this type of profile results in a rapid reduction in the area under vacuum during the crushing of the cellular material 8. When one wish to seize these large items, he is otherwise preferable to make cavities 10 with walls 11 having a concave curvilinear profile as illustrated by figure 4 in order to maintain a large part of the surface in depression whatever the degree for crushing the cellular material 8. Walls 11 planar therefore constitute an interesting compromise between the capacity adaptation to articles of various dimensions while now in depression a surface of a size satisfactory allowing lifting of the articles.

In this regard, it will be noted that during the implementation depression flat walls tend to take a curvilinear form which is all the more pronounced as the depression is stronger and when the foam material is closed cell. It is therefore necessary to take into account these data when determining the form and dimensions of the cavities. In this regard we will also note that after gripping an article the degree of crushing tends to balance automatically. Indeed a crush too important results in a decrease in the surface application of depression, this decrease being all the stronger as the inclination of the walls by compared to a horizontal plane is weaker. When the vacuum application surface is weak the force lift of the item is itself weak so due to its weight, the article tends to move away from the base of the box. This has the effect increase the area of application of the vacuum until a balance is reached between the weight of the article and the lift force, provided well understood that the maximum lift force that can be obtained is greater than the weight of the article.

Of course, the invention is not limited to the mode described and we can make variants without departing from the scope of the invention such as defined by the claims.

In particular, although the material plate deformable has been illustrated as a material alveolar we can realize this in other forms, for example in the form of one or more bags of material flexible hung under the sole, filled with liquid or small beads, and having eyelets facing the suction ports 3.

Although the sheet of foam material was illustrated as a single homogeneous layer, we can make a plate with different layers associated in order to achieve a laminated structure adapted to a particular application. Rather than set up rigid inserts 13 in the holes 9, provision may be made to produce a laminated plate structure comprising a relatively firm layer in contact with sole 2 of box and a softer layer in contact with the items to lift.

Although the invention has been illustrated in relation with a sheet of foam material in one piece, we can plan to make it in several pieces each comprising one or more rows of cavities and arranged side by side on the sole of the head gripping.

Although the invention has been illustrated with cavities 10 centered on the holes 9, we can provide off-center cavities with respect to the holes 9, in particularly around the perimeter of the gripping head.

Although the invention has been described in relation with a gripping head comprising compartments 4 the upper opening of which can be closed by a flap, reducing the size of the suction openings 3 which is made possible by the invention makes it possible to envisage in some cases to delete compartments 4 and maintain suction through all ports suction 3 even when these are not opposite of an item to be lifted.

Claims (10)

Suction gripping head comprising a box (1) having a sole (2) pierced with orifices suction (3), this sole (2) being equipped with a plate of deformable material (8) having opposite suction holes (3) of the holes (9) passing through the plate and associated with cavities (10) opening onto a underside of the plate, each cavity (10) having deformable walls (11) inclined towards a bore (9) opening into the cavity, characterized in that the cavities are formed in the thickness of the plate deformable material (8) and in that the walls (11) deformable extend in the immediate vicinity of the hole (9). Gripping head according to claim 1, characterized in that the cavities (10) are centered on the holes (9). Gripping head according to claim 1 or claim 2, characterized in that the holes (9) in the plate of deformable material have rigid inserts (13). Gripping head according to any one of previous claims, characterized in that the cavities (10) have an edge delimiting a periphery generally rectangular. Gripping head according to any one of previous claims, characterized in that the absence of objects seized the walls (11) of the cavities (10) are substantially flat. Gripping head according to claim 5, characterized in that the walls (11) intersect according to intersection lines (12) converging towards one end adjacent to the holes (9) but not intersecting in the vicinity of it. Gripping head according to claim 5 or claim 6, characterized in that the walls of the cavities (10) form an angle of about 10 ° with a plane horizontal. Gripping head according to one of Claims 1 to 4, characterized in that in the absence objects seized the walls (11) of the cavities (10) are concave curvilinear. Gripping head one of claims 1 to 4, characterized in that in the absence of seized objects, the walls (11) of the cavities (10) are convex curvilinear. Gripping head according to one of previous claims, characterized in that the walls (11) of the cavities (10) are covered with a skin (14).

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