Suction device for reversible adhesion to a substrate surface

Abstract

A suction device, in particular a suction cup, suction lifter, or vacuum gripper, for reversible attachment to a substrate surface, comprising a first component, which is used for the actuation of the suction device, and a second component, which can be brought into contact with the substrate surface via the suction cup surface, wherein the first component consists of at least one harder first material and the second component of at least one, in comparison to the first material, softer second material, wherein the second material is an extremely soft material with a Shore 00 hardness less than 50, wherein the thickness of the second component measures, in an unloaded condition, at least 2.5% of an outer diameter or a length or a width of the first component and/or particles and/or fibers, which are harder than the second material, are integrated into at least one second material.

Claims

1. A suction device, in particular a suction cup (1), suction lifter, or vacuum gripper (1V), for reversible attachment to a substrate surface (2), comprising a first component (3), which is used for an actuation of the suction device, and a second component (4), which can be brought into contact with the substrate surface (2) via a suction cup surface (5), wherein the first component (3) is made of at least one harder first material and the second component (4) of at least one, in comparison to the first material, softer second material, wherein the second material is a soft material with a Shore 00 hardness less than 50, and that a thickness (d2) of the second component measures, in an unloaded condition, at least 2.5% of an outer diameter (D1) or a length (L) or a width (B) of the first component (3) and/or that particles (6) and/or fibers, which are harder than the second material, are integrated into at least one second material.

2. The suction device according to claim 1, wherein the said softer second material of the second component (4) has a Shore 00 hardness less than or equal to 35.

3. The suction device according to claim 1, wherein the said second component (4) extends inward from a circumferential margin over at least 55% of a total area of the first component (3) and toward the substrate surface (2).

4. The suction device according to claim 1, wherein the said second component (4) extends over at least 65% of a total area of the first component (3).

5. The suction device according to claim 1, wherein the said second component (4) extends over at least 75% of a total area of the first component (3).

6. The suction device according to claim 1, wherein the said softer second material of the second component (4) has a thickness of 3% to 8% of an outer diameter (D1) or a length (L) or a width (B) of the first component (3).

7. The suction device according to claim 1, wherein the said softer second material of the second component (4) has a thickness of 3.5% to 7% of an outer diameter (D1) or a length (L) or a width (B) of the first component (3).

8. The suction device according to claim 1, wherein the first component (3) has an outer diameter (D1), and the second component (4) has a comparably larger outer diameter (D2).

9. The suction device according to claim 1, wherein at least one second material of the second component (4) consists of at least one polymer and/or at least one elastomer or a combination of one or more polymers and/or elastomers.

10. The suction device according to claim 1, wherein columns with an annular or angular cross-section are embedded in the second component (4) and consist of an elastic material, which is harder than said softer second material of the second component.

11. The suction device according to claim 1, wherein projections and/or a structure (3a) protrude out of the first component (3), reach into the second component (4) and, while a contact pressure is exerted, are pressed into the second component (4) and the substrate surface (2).

12. The suction device according to claim 1, wherein particles (6) and/or said fibers and/or columns, which are integrated into the material of the second component (4), can be at least partly pressed into the indentations of a surface profile of the substrate surface (2).

13. The suction device according to claim 1, wherein at least one second material of the second component (4) is a swellable material and/or the second material contains swellable particles and/or the second component (4) is coated with a swellable material on the suction cup surface (5).

14. The suction device according to claim 1, wherein the suction cup (1) contains a grip or connection element (7) and/or the vacuum gripper (1V) contains a connection for a vacuum pump, whereby a vacuum between the suction cup (1) or the vacuum gripper (1V) and the substrate surface (2) can be generated.

15. The suction device according to claim 1, wherein the first component (3) of the suction device in the form of the vacuum gripper (1V) or the suction lifter is made of a very hard material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be described in the following by examples and corresponding figures, without being reduced to these.

(2) Wherein is shown:

(3) FIG. 1: a cross-section of an exemplary embodiment of the suction cup according to the invention which rests on a substrate surface

(4) FIG. 2: a cross-section of the exemplary embodiment according to FIG. 1 which is attached to the substrate surface

(5) FIG. 3: detail X according to FIG. 2

(6) FIG. 4: a cross-section of column-like, embedded structures

(7) FIG. 5: a longitudinal cross-section of column-like, embedded structures in an unloaded condition

(8) FIG. 6: a longitudinal cross-section of column-like, embedded structures in a loaded condition

(9) FIG. 7: a cross-section of another exemplary embodiment of the solution according to the invention with a vacuum connection

(10) FIG. 8: a top view of an exemplary embodiment of the suction cup according to the invention with the first component extending over the whole area

(11) FIG. 9: a top view of another exemplary embodiment of the suction cup according to the invention with a grid-shaped first component

(12) FIG. 10: a top view of another exemplary embodiment of the suction cup according to the invention with a star-shaped first component

(13) FIG. 11: a top view of another exemplary embodiment of the suction cup according to the invention with an alternatively shaped first component

(14) FIG. 12: a top view of a schematic diagram of a vacuum exhauster with the first component made of a hard material such as steel or aluminum

(15) FIG. 13: vacuum exhauster according to FIG. 9 as a schematic diagram in cross-section

(16) FIG. 14: a bottom view of an alternative embodiment of the second component of the suction cup

(17) FIG. 15: A) a bottom view of the second component with projections/structures; B) projections/structures arising from the first component are pressed under contact pressure into the second component and the roughness profile of the substrate surface

(18) FIG. 16: attachment variations of the suction cup: A) and B) suction cup attached to a metal ridge stock; C) suction cup holding a stone of approximately 1 kg

(19) FIG. 17: a diagram illustrating the relationship between the pull-off force in kg and the thickness of the second component in mm

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(20) In FIG. 1 a cross-section of an exemplary embodiment of the suction cup 1 according to the invention, which rests on a substrate surface 2, is shown. The suction cup 1 comprises a first component 3 with a thickness d1 and a second component 4 with a thickness d2. The first component 3 is made of a first material. The second component 4 is made of a second material, which is considerably softer than the material of the first component 3. The second component 4 is detachably or non-detachably connected to the first component 3 or formed in one piece. Both the first component 3 and the second component 4 extend over the whole area. The outer diameter D1 of the first component 3 is smaller than the outer diameter D2 of the second component 4.

(21) The suction cup surface 5 comes into contact with the substrate surface 2 while applying the suction cup 1 to the substrate surface 2 of any substrate or component/item.

(22) Particles 6 are embedded in the second material of the second component 4. When contact pressure is exerted toward the substrate surface 2, for example by the pressing of the grip or connection element 7 of the suction cup 1 onto the substrate surface 2 or by the subsequent restoring force of the first component 3, those particles are pressed with the comparably soft second component 4 into the suction cup surface 5 and with this into the substrate surface 2, where the particles 6 may arrange themselves fully or partly in the indentations of the substrate surface 2, causing increased friction between the suction cup surface 5 and the substrate surface 2 (see FIG. 3).

(23) By pressing the second component 4 toward the substrate surface 2, the fluid in the cavity between the suction cup 1 and the substrate surface 2 is at least partly pressed out and a lower pressure compared to the ambient pressure is generated, whereby, after releasing the pressing force F1 on the first component 3 of the suction cup, the suction cup 1 attaches to the substrate surface 2. This functions in fluids in the form of gaseous media (e.g. air) and liquid media (e.g. water).

(24) A non-limited, exemplary embodiment is a suction cup 1 with a diameter (equating the outer diameter D1 of the first component 3) of 50 mm to 70 mm, preferably 65 mm, whose second component 4 has a thickness of 1 mm to 5 mm, preferably 2 mm to 3 mm. The first material of the first component 3 has a Shore A hardness of 60 to 80 and a complex modulus (G*) of 10 to 50 MPa, while the second material of the second component 4 has a Shore 00 hardness between 10 and 30 (<5 Shore A) and a complex modulus (G*) of 0.025 MPa.

(25) Such an exemplary suction cup can attach very well to a substrate surface 2 with a coarse surface roughness, such as substrate surfaces with Rt (peak-to-valley height) up to 1 mm to 2 mm and larger or a grain size of 1 mm to 2 mm or a variation of 1 mm to 2 mm in the structural heights of the substrate surface 2. Such a suction cup 1 may also effectively attach to a substrate surface 2 with a radius of curvature of 2.5 to 4 cm or less or more. In order to attach, the suction cup 1 is pressed toward the substrate surface 2 with a pressing force F1 (see FIG. 1). Since the suction cup 1 is convexly arched on the outside, the cavity, which is created between the suction cup surface 5 and the substrate surface 2 of the substrate, is reduced by pressing down, and a lower pressure in comparison to the ambient pressure is generated.

(26) FIG. 2 illustrates a cross-section of the said embodiment of the suction cup 1 of the invention (according to FIG. 1) which was pressed onto the substrate surface 2 and attaches to it. The elastic first component 3 creates a force to restore it to its original shape according to FIG. 1, by which a lower pressure in the cavity h between the substrate surface 2 and the second component 4 is generated, by which the attachment is created.

(27) It can be recognized that both the first component 3 and the second component 4 comply elastically, and the suction cup 1 with the suction cup surface 5 is pressed onto the substrate surface 2, and the second component 4 with its broad margin has adapted to the substrate surface 2. The particles 6 integrated into the second component 4 are much harder than the material of the second component 4 and are pressed through the comparably soft second component 4 toward the substrate surface 2, where they are at least partly forced into the recesses and/or indentations of the substrate surface 2 (see FIG. 3) and thereby cause an increased friction.

(28) If a pull-off force F2 on the grip or connection element 7 is applied vertically to the substrate surface 2, the margin of the first component 3 is more strongly pressed by its restoring force (and by the consequentially increasing lower pressure) toward the substrate surface 2 with a counterforce FG, thereby increasing the friction between the suction cup surface 5 and the substrate surface 2. Not until the force F2 is large enough to exceed the friction force between the suction cup surface 5 and the substrate surface 2 does the suction cup 1 detach from the substrate surface 2.

(29) Moreover, it is possible to detach the suction cup by at least partly lifting its margin so that a pressure equalization with the ambient pressure can occur.

(30) The magnified detail in FIG. 3 illustrates how particles 6 are pressed into the indentations of substrate surface 2, whereby the friction between the substrate surface 2 and a non-specified suction cup surface at the second component 4, which is located under the first component 3, is increased.

(31) In suction lifters, after placing the suction cup on the substrate, the center of the first component 3 is raised, whereby the lower pressure is generated and the suction cup attaches to the substrate.

(32) FIG. 4 illustrates an exemplary cross-section and FIG. 5 a longitudinal cross-section of the columns 6.1, embedded in the second material of the second component 4, that are hexagonally shaped and arranged like honeycombs. The largest distance in the cross-section of the columns 6.1b (the diameter in a circular cross-section) measures 0.1 mm to 5 mm. The distance between the columns 6.1 preferably measures between 0.1 mm and 0.5 mm. The height of the columns 6.1h preferably measures between 0.1 mm and 0.5 mm.

(33) The dimensions of the columns 6.1 and their interspaces may be chosen given the dimensions of the suction cup, particularly the thickness of the second component, and may be larger for large diameters and/or thicknesses of the second component 4.

(34) Additionally, particles 6 may be embedded in the material of the second component 4. The longitudinal cross-section of the embedded column-like structures or columns 6.1 in a loaded condition in accordance with FIGS. 4 and 5 is illustrated in FIG. 6. Their height 6.1h particularly measures 0.2 mm to 4 mm. The columns, here in combination with the embedded particles 6, lead to improved stability and friction properties of the second component 4 and simultaneously ensure extremely good adaptation to the strong surface irregularities of the substrate S shown in FIG. 6. The extremely soft, surrounding material enables a certain movability of the columns 6.1 toward the support/substrate S while simultaneously ensuring the sealing to the sides of the suction cup and to the substrate S. In FIGS. 5 and 6 it is evident that, at the side opposite the substrate, the columns 6.1 are connected by a supporting layer and are preferably shaped as one piece.

(35) In FIG. 7 a cross-section of another embodiment of the solution according to the invention in the form of a vacuum gripper 1V, which was loosely placed on a substrate surface 2 and comprises a vacuum connection 7.1, is illustrated. In this embodiment, the second component 4 does not extend over the whole area but is shaped like an O-ring. In this version, it does not extend over the circumferential margin of the first component 3, which, however, would also be possible.

(36) In both cases an optimal sealing at the contact area between the substrate surface 2, at which the suction cup 1 shall be attached, and the second component 4 is ensured. The suction cup 1 has a perforation 1.1 in the area of the vacuum connection 7.1 so that air may be evacuated or supplied. The first component 3 has a thickness d1 and the second component 4 a thickness d2. The thickness d2 of the second component 4 is just slightly larger here than the thickness d1 of the first component 3.

(37) After the vacuum gripper 1V is placed on the substrate surface 2, air is sucked out of the cavity between the substrate surface 2 and the suction cup surface 5; thereby the vacuum gripper 1V with its suction cup surface 5 is sucked or pressed onto the substrate surface 2 and firmly attaches to it (not illustrated). For detachment, air is brought in again via the vacuum connection 7.1, and thereby the attachment between the suction cup surface 5 and the substrate surface 2 is released.

(38) A top view of an embodiment of the suction cup 1 according to the invention with a first component 3 extending over the whole area is illustrated in FIG. 8. Moreover, it is possible that, between the grip or connection element 7 and the margin of the suction cup 1, the first component 3 is grid-shaped, as shown in FIG. 9, or star-shaped, as shown in FIG. 10.

(39) Other shapes of the first component 3, as exemplarily illustrated in FIG. 11, are also conceivable as long as they ensure a regular transfer of contact pressure on the second component 4.

(40) In FIGS. 12 and 13 a vacuum gripper for industrial application is shown, which in top view essentially has a quadrangular basic shape with a length L and a width B. The first component 3 is essentially designed to be stiff and casinglike with a reduced thickness d1 and possesses, toward the second component 4, a flange 3.1 pointing outward. The first component 3 may, for example, be made of metal, such as steel or aluminum, or of a stiff plastic or of a combination of the said materials. Below the flange 3.1 is the second component 4, which is formed as a circumferential band following the profile of the flange 3.1 and which has a thickness d2.

(41) In the illustrated embodiment, the second component 4 extends inwardly and outwardly beyond the flange 3.1. According to one non-illustrated variation, the second component 4 may also only extend inwardly or outwardly beyond the flange 3.1 or may also terminate at it.

(42) The second component 4 also contains particles 6 and/or fibers (which are not identified here) and rests via its suction cup surface 5 on the substrate surface 2 of a substrate S. The first component 3 has a perforation 1.1, followed by a connection 7.1 to a, non-illustrated, vacuum hose, which is connected to a vacuum pump. When the suction cup surface 5 rests on the substrate surface 2, air is sucked out of the cavity between the vacuum gripper 1V and the substrate surface 2 by a vacuum pump, whereby a lower pressure in comparison to the ambient pressure is generated, and the vacuum gripper 1V with its second component 4, on which the flange 3.1 of the first component 3 acts, is pressed onto the substrate surface 2.

(43) Now, the substrate S, which is attached to the vacuum gripper 1V, can be lifted by means of the vacuum gripper 1V (at which one or more, non-illustrated, handling elements may also be provided) and in accordance with the construction or manufacturing task can be moved and released again. Then, the vacuum gripper 1V (or vacuum bell) is removed from the substrate surface 2 by equalizing the pressure in the cavity with the ambient pressure or by applying a slightly higher pressure.

(44) The second component 4 is preferably detachably and air-tightly connected with the first component 3, and, therefore, in the case of deterioration or use on a different substrate surface, it may be exchanged.

(45) The thickness d2 of the second component 4 of a suction device should, in an unloaded condition, measure more than 2.5%, preferably 3 to 8%, and especially preferably 3.5 to 7% of the largest dimension of the first component 3 that extends in the plane of the substrate surface 2 (i.e. the outer diameter D1, a length L, or a width B, depending on the design). In vacuum grippers, which have a very large diameter or a very large length or width and in which the contact pressure on the second component is generated by vacuum and not by the restoring force of the first component, the thickness d2 of the second component may measure less than 2.5% of D1, L, or B.

(46) According to a non-illustrated embodiment, the particles/fibers and/or the column-like structures in the second layer of the second component 4 may not be distributed over the whole cross-section of the second component 4, but rather they may be located in the material of the second component only close to the suction cup surface 5. Moreover, according to a non-illustrated embodiment, it is possible to realize the second component 4 without the particles/fibers and/or the column-like structures and cover it with a very thin, but also elastic, very soft layer which contains the particles/fibers and/or the column-like structures. Moreover, it is possible to arrange the particles/fibers and/or the column-like structures in different regions of the second, extremely soft component 4.

(47) This is exemplarily illustrated in FIG. 14. In the second component 4 is a first annular region 4.1 without particles, and radially inward from this extends a second annular region 4.2 with particles 6, and radially inward from that extends a third annular region 4.3 with columns 6.1. In the remaining inner region 4.4 no particles 6 or columns 6.1 are integrated. The order of these regions can also change. Moreover, in accordance with a non-illustrated embodiment, an annular region with larger particles and an annular region with smaller particles may be combined, and, optionally, an annular region with some column-like structures may be included as well.

(48) According to FIG. 15, improved friction may also be achieved by projections/structures 3a protruding from the first component 3 and reaching into the second component 4. When a contact pressure is applied toward the substrate surface 2, the said, for example point-shaped, projections of the first component 3 are pressed into the indentations of the surface structure of the substrate surface 2 and increase friction.

(49) FIG. 15 illustrates in drawing a) a bottom view of the first component 3 with projections 3a and in drawing b) the projections/structures 3a in the first component 3, which under a contact pressure, are pressed into the second component 4 and into the roughness profile of the substrate surface 2.

(50) Wherein, it is important that the said projections 3a do not completely penetrate the second component 4 toward the substrate S but that they are only strongly pressed into the latter.

(51) The suction cup according to the invention may be applied on very rough surfaces such as metal ridge stock (whose surface may have structures with a height up to 2 mm) and can also be applied underwater. Metal ridge stock is sheet metal with a diagonally-ribbed structure.

(52) In FIG. 16 the attachment of the suction cup 1 is illustrated; in a) and b) the substrate S is a metal ridge stock, and in c) the substrate S is a stone. The metal ridge stock as the substrate S possesses projections, arranged in a staggered way 2.1, at the substrate surface 2 with a structural height of 1.2 mm, and the stone as the substrate S possesses a roughness/structure of 1 mm to 2 mm with superimposed waviness and coarse shape variation. By pressing down the suction cup 1, the extremely soft second component 4 adjusts to the substrate surface 2 and encloses the ridges 2.1, which is particularly recognizable in drawing b), so that a lower pressure can develop and the suction cup 1 attaches to the substrate S. The suction cup 1 was loaded with 0.8 kg by means of a hook H connected to a grip or connection element 7. According to drawing c) a substrate S attached to the suction cup 1 is a stone with a weight of approximately 1 kg.

(53) There is a clear connection between the thickness of the second component 4 and the maximal roughness or structuring of the substrate surface 2, to which the suction cup can attach. In the specific embodiment of a suction cup according to FIG. 1 with a diameter D1=60 mm, the optimal thickness of the second component 4 is 2.5 mm to 5 mm, 4% to 8% of the diameter D1 respectively (see table 1).

(54) TABLE-US-00001 TABLE 1 Relationship between the thickness d1 of the second component 4 and attachment to substrates with increasing roughness. Second component 4 Substrate (grain size in mm) Thickness d2: A1 A2 A3 A4 A5 A6 A7 mm % 0 mm 0.1 mm 0.2 mm 0.5 mm 1-2 mm 1.5-2.5 2-6 mm 1 1.7 x x x — — — — 1.5 2.5 x x x — — — — 2 3.3 x x x (x) (x) — — 2.5 4.2 x x x x x — — 3 5 x x x x x x — 4 6.7 x x x (x) x x (x) 5 8.3 x x x x x x (x) 6 10 x x (x) (x) — — — x attaches, (x) attaches but not reliably, — does not attach

(55) Increasing the thickness of the second component 4 increases the tolerated roughness proportionally. Consequently, an extremely soft second component 4 with a low thickness only enables attachment to slightly rough surfaces (up to grain size 200 μm). On very rough surfaces, suction cups with too small of a thickness of the second component 4 fail. A minimum thickness of 2.5 mm (4.2% of the suction cup diameter D1) enables, in the said embodiment, a reliable attachment to very rough surfaces (A4-A7).

(56) FIG. 17 illustrates the pull-off force of the said embodiment with an increasing thickness d2 of the second component 4 on a very rough substrate of 1 mm to 2 mm grain size. While suction cups with a thickness d2 of the second component smaller than 2 mm do not attach, a reliable attachment with attachment forces up to 14 kg (normal force, 14 kg equals 137 N) is gained for a thickness of the second component of 2.5 mm to 4 mm (4.2% to 6.7% of the suction cup diameter D1). FIG. 17 shows the relationship between the pull-off force of a suction cup in kg versus the thickness d2 of the second component 4 of the suction cup in mm.

(57) It is possible to determine the optimal configuration of a suction cup that is most applicable for a substrate surface by means of pretests.

LIST OF REFERENCE NUMERALS

(58) 1 Suction cup 1V Vacuum gripper 1.1 Perforation 2 Substrate surface 2.1 Ridge 3 First component 3.1 Flange 3a Projection/structure 4 Second component 4.1 First annular region 4.2 Second annular region 4.3 Third annular region 4.4 Inner region 5 Suction cup surface 6 Particle 6.1 Columns 6.1b Widest region 6.1h Height 7 Grip or connection element 7.1 Vacuum connection B Width D1 Outer diameter of the first component D2 Outer diameter of the second component d1 Thickness of the first component d2 Thickness of the second component F1 Pressing force F2 Pull-off force FG Counterforce h Cavity H Hook L Length S Substrate