Vacuum retaining system

Abstract

A retaining system for a flat-surface workpiece is disclosed, comprising a retaining body that has a handle portion (1) which protrudes from a base (2) including a vacuum chamber (3) bordered by a perimeter seat (4) defined on the bottom side thereof, a first flexible sealing lip (8a) engaged in said perimeter seat (4), in which said retaining body is associated in a package (9) with a second sealing lip (8b) that is alternative and of different yielding characteristic to said first flexible sealing lip (8a).

Description

[0001] VACUUM RETAINING SYSTEM

[0002] DESCRIPTION

[0003] Technical field

[0004] The present invention relates to a vacuum retaining system, in particular a retaining system for lifting flat plates . Background art

[0005] There have long been various retaining devices on the market that are used to hold and lift heavy obj ects by acting on a respective flat face . Typically, these retaining devices are used to lift flat sheets , such as glass plates , tiles , large stone slabs and so on .

[0006] The simplest retaining devices consist of a shaped retaining body with a handle , on one side of which a suction cup that adheres to the surface by creating a vacuum is provided . These devices are very common and can be used individually or combined on a more complex structure ( e . g . in glass plate lifters ) .

[0007] The suction cup simply consists of a flexible lip, e . g . made of rubber, which is arranged in a flat closed perimeter (e . g . circle ) around a cavity that defines a chamber with a defined volume . The flexible lip acts as a seal of the chamber against the flat plate to be retained . Pressing the flexible lip against the flat surface of the plate reduces the available volume of the chamber, thus expelling air and creating a partial vacuum that holds the plate to the suction cup .

[0008] An improved version of these devices also includes a hand pump to further empty the air from the suction cup chamber, so that a higher vacuum can be created ( apart from that caused by the compression of the flexible lip ) .

[0009] More recently, retention devices have been developed in which the vacuum pump is not manual but it is driven by an electric motor . In this way, it is also possible to automatically restart the electric pump whenever a vacuum sensor detects that the pressure inside the chamber tends to rise (e . g . due to a slight leakage of the perimeter seal allowing air to enter from outside ) .

[0010] Such devices are illustrated for example in DE202009004659U, All of these devices , according to which the preamble of the attached main claim is constructed, comprise a retaining body having a handle portion protruding from a base defining a vacuum chamber and a sealing lip j oined perimeterally to the base to seal the vacuum chamber . The handle portion is then fitted with a housing for a motorised vacuum pump, its power supply (to be connected to the mains or storage batteries ) and appropriate control switches .

[0011] All these solutions involve the use of a sealing lip of flexible material , e . g . elastomeric rubber . The material of the sealing lip is chosen of an appropriate porosity and hardness according to the material against which it is to be sealed . A compromise must be exercised in this choice : if the material has a very rough surface (e . g . an uneven stone slab ) , the sealing lip must adapt well to the roughness and it is therefore made of a very yielding material which, conversely, will tend not to guarantee a perfect seal and the maximum load that the device can withstand will not be high; on the contrary, with a smooth material (e . g . a glass slab ) , the sealing lip can be made of a harder material and will guarantee a better seal , so that a high maximum load can be attained .

[0012] Existing devices are therefore dedicated to a specific material and cannot be used universally .

[0013] To compensate for this limitation, it has been suggested to employ a very complex sealing lip consisting of two materials with dif ferentiated yielding characteristics . This construction may have a more flexible use , but it is more expensive and can be inconvenient to use if in fact it is almost always used with the same material .

[0014] The need is therefore felt for a retaining device that does not suf fer from the limitations of known technology, while remaining sufficiently economical and effective even when used almost always with the same material .

[0015] Summery

[0016] The purpose of the present invention is therefore to provide a vacuum retaining system for flat surfaces , which enables effective adhesion to surfaces of various kinds .

[0017] This is achieved with a retaining system as described, in its essential features , in the attached claims .

[0018] In particular, according to the invention, a retaining system is provided for a flat-surface workpiece , comprising a retaining body having a handle portion protruding from a base including a vacuum chamber bordered by a perimeter seat defined on a bottom side , a first flexible sealing lip engaged in said perimeter seat and in which said retaining body is associated in a package with an alternative second sealing lip having a dif ferent yielding characteristic to said first flexible sealing lip .

[0019] Preferably the first flexible sealing lip is of non-marking silicone rubber and the second flexible sealing lip is of closedcell or open-cell foam rubber .

[0020] According to another aspect , the perimeter seat has two adj acent grooves , an inner and an outer one divided by a thin septum, and the first flexible sealing lip has a cross-section with two adjacent rectangular portions , separated by a notch and designed to fit into said two grooves of the perimeter seat .

[0021] In another aspect , the second flexible sealing lip has a cross-section being a single rectangular shape designed to fit into the outermost groove of the perimeter seat .

[0022] Advantageously, the handle portion houses an automatic vacuum pump that is in fluid connection with the vacuum chamber by means of passage holes pierced in the base .

[0023] According to a further aspect , the first sealing lip has shimming means in the form of a chamfer portion, on the inner side of an outermost perimeter portion, which has increasing thickness going towards the outermost perimeter area .

[0024] Alternatively, the first sealing lip has shimming means in the form of a protruding section on an outermost perimeter area .

[0025] Alternatively, the perimeter seat has shimming means in the form of a sloping back wall with increasing thickness towards the outermost perimeter area .

[0026] In a further aspect , the shimming means determine a protruding height of the first sealing lip that is greater in areas further away from the centre of gravity of the perimeter seat than in areas closer to the centre of gravity .

[0027] Brief description of the drawings

[0028] More details on the features and advantages of the system according to the invention will, however, become clearer from the following description, given as an example and illustrated in the accompanying drawings , in which fig . 1A is a photographic perspective view of a system according to the invention;

[0029] Fig . IB is a photographic detailed perspective view of the bottom side of the retaining body and sealing lips according to the invention;

[0030] Fig . 2A is a cross-sectional view of a first variant of a first sealing lip according to the invention;

[0031] Fig . 2B is a cross-sectional view of a first seat housing a sealing lip according to the invention;

[0032] Fig . 2C is a cross-sectional view of a second variant of the first sealing lip according to the invention;

[0033] Fig . 2D is a cross-sectional view of a second seat housing a sealing lip according to the invention;

[0034] Fig . 2E is a cross-sectional view of a third variant of the first sealing lip according to the invention;

[0035] Figs . 3A-3C are perspective photographic views of a system according to the invention used on different surfaces .

[0036] Detailed description

[0037] An automatic vacuum retaining system is depicted in Fig . 1 . It consists , in a way which is known per se , of a retaining body having a handle portion 1 protruding from a base 2 in which is defined, on its bottom side , a vacuum chamber 3 delimited by a perimeter seat in the form of a recess or groove 4 .

[0038] A housing is defined in the handle portion 1 for an electrical storage battery 5 and a vacuum pump (not shown) controlled by a control panel 6 . The vacuum pump is intended to suck air from suction holes 7 provided in a dome surface of the vacuum chamber 3 , so as to reduce the pressure in the chamber 3 to predetermined levels compatible with the maximum load supported by the system .

[0039] A flexible sealing lip is inserted into the perimeter seat 4 to create a tight seal between the vacuum chamber 3 and a flat surface against which the lip contacts . For this purpose, the sealing lip is laid along to a closed geometry perimeter shape equivalent to that of the perimeter seat 4 , for example according to a ' biscuit ' or elliptical design .

[0040] According to the present invention, the retaining system comprises at least two sealing lips 8a and 8b and a possible package or transport box 9 capable of accommodating the various components of the system together .

[0041] A first sealing lip 8a is of higher stif fness and is intended to seal on a flat surface with low roughness . For example, the first sealing lip 8a is made of non-marking silicone rubber . A second sealing lip 8b has higher yielding characteristic and is also intended to seal on a rough or uneven surface . For example, the second lip 8b is a so-called closed cell ( e . g . neoprene, epdm, polyethylene or other) or open cell ( e . g . polyurethane foam, melamine or other ) foam rubber .

[0042] The second yielding lip 8b can have a simple rectangular cross-section ( see Fig . IB) and be accommodated by mechanical engagement with seat 4 .

[0043] The first lip 8a, being of a stif fener material, preferably has a more complex cross-section ( see Fig . 2A) , optimised to ensure an effective seal on the surface to which it adheres and of a wide width, for example 2-4 cm . The section of the first lip 8a according to a preferred embodiment consists of a pair of rectangular geometric figures , j oined together, provided with a series of grooves or ridges on the lower surface (the one facing the surface of the material to be adhered to ) , for example seven grooves and eight ridges . In particular, when viewed in section, the profile of the first sealing lip 8a has an outer portion (with respect to the perimeter of chamber 3 ) and an inner portion, separated from each other by a notch that extends partially into the thickness of the lip.

[0044] This specific shape is particularly effective for stiffer material because it enlarges the contact surface of the sealing lip 8a and defines geometric structures that yield properly under the action of the vacuum created by the vacuum pump. This configuration helps to achieve high vacuum levels so that the device can lift high loads, e.g. in excess of 200 kg.

[0045] For this purpose, the perimeter seat 4 (fig. 2B) preferably has two grooves to accommodate the sealing lips : an outermost groove, which fully accommodates the second, more yielding lip 8b and the outer portion of the first sealing lip 8a; an inner groove housing the inner portion of the first sealing lip 8a.

[0046] Between the two housing grooves there is provided a separating rib or septum, intended to fit into the notch of the first sealing lip 8a.

[0047] According to an alternative embodiment (fig. 2C) , the outermost perimeter portion of the first sealing lip 8a has a chamfer 8a' on the inner side (i.e. the one intended to rest near the bottom of the seat 4) . This chamfer 8a' reduces the bearing surface of the lip inside its seat 4 and increases locally - i.e. in the perimetrically outermost area - the yielding of the sealing lip 8a. This is particularly advantageous in an initial operational phase of vacuum creation in chamber 3, because the lip yields quickly along the outermost perimeter line, ensuring the initial hermetic seal which then guarantees a rapid reduction in pressure inside chamber 3.

[0048] According to another embodiment (Fig. 2E) , the outermost perimeter portion of the first sealing lip 8a instead has a short raised section 8a' ' on the outer side (i.e. the one intended to contact the plate to be lifted) . The short raised section 8a' ' is, for example, a section having some ridges (e.g. two ridge lines) having a greater height. This raised section has the same function of determining a portion with greater yielding which quickly ensures that the vacuum chamber is held against the surface of the slab in the first operational phase of creating a vacuum in the chamber .

[0049] Finally, fig . 2D illustrates a dif ferent shape of the housing seat 4 which allows the same ef fect as indicated above to be obtained by employing a rectangular section sealing lip (as in fig . 2A) . In particular, the bottom of the housing seat 4 , at its outermost perimeter portion, has an inclined bottom wall 4 ' , which keeps the bottom surface of the first lip 8a inclined : in this way, an effect similar to that of the lip illustrated in fig . 2E is obtained .

[0050] In the embodiments illustrated in Figs . 2C-2E , the variation in thickness of the first lip or the bottom of the seat 4 may also be dif ferentiated according to the peripheral zone . For example , taking into account the inherent flexibility of the device during the suction phase , it is considered advantageous that the first lip should protrude from its seat by a greater extent in areas further away from the centre of gravity of the perimeter geometry of the seat than in areas closer to the centre of gravity .

[0051] The system according to the invention, of fered together with a container 9 , constitutes a kit for use by the operator that allows the retaining device to be adapted to the surface to which it is to adhere by applying a vacuum with the vacuum pump .

[0052] As depicted in Figs . 3A and 3B, the system can work effectively with different surface finishes of a slab (or other flat surfaced piece ) to be lifted or moved . If the surface is suf ficiently smooth (Fig . 3A) , in seat 4 the operator leaves the first sealing lip 8a installed, which permanently provides a high vacuum in chamber 3 and thus allows a high load to be supported by the handle portion 1 . I f , on the other hand, the surface is rough / porous and / or uneven (Fig . 3C) , in seat 4 the operator replaces the second sealing lip 8b, which still provides suf ficient sealing despite the surface roughness , even if it does not allow for a high vacuum in chamber 3 . In intermediate surface conditions (Fig . 3B ) , the operator can use the sealing lip that he considers the best compromise, or he can use a third type of lip that should be provided in the kit .

[0053] The third type of lip available (not illustrated) could, for example , be similar to the first lip, but made of acrylonitrile butadiene rubber, which is harder and ' stickier ' than a silicone rubber, although it has the disadvantage of leaving traces of material (and can therefore be used on plates that do not suffer aesthetically from possible rubber residue ) .

[0054] As is well understood from the description above , the system according to the invention perfectly achieves the purposes set out in the introduction .

[0055] In fact , in the kit system, a traditional vacuum device is provided, to which it is associated - at an extremely low cost - at least one alternative sealing lip, made of a material that is significantly more yielding or, on the contrary, more stif f than the basic one . This provides the operator with the possibility of using the system with different materials , without operation being made dif ficult or complicated by the simultaneous presence of seals of a different nature .

[0056] The specific configuration of the stiffer lip is particularly well suited to be able to function effectively while being installed in the same location as the more yielding lip .

[0057] Embodiments that provide shimming means on the perimeter area of the more stiff lip, i . e . the chamfered or thicker lip and the seat with a partially sloping bottom wall , achieve greater yielding in the outermost perimeter portion, facilitating the vacuum creation phase because they allow an initial perimeter seal of the chamber to be quickly obtained, which then guarantees the subsequent suction at a more extreme vacuum level .

[0058] It is understood, however, that the protection of the abovedescribed invention is not limited to the particular configuration illustrated, but extends to any other equivalent design variant .

[0059] For example, the design of the handle and base portion are not necessarily limited to those illustrated here . Likewise, the materials and number of sealing lip made available in the kit may dif fer from those described .

Claims

CLAIMS1. Retaining system for a flat surface piece, comprising a retaining body having a handle portion (1) which protrudes from a base (2) including a vacuum chamber (3) bordered by a perimeter seat (4) defined on the bottom side thereof, a first flexible sealing lip (8a) engaged in said perimeter seat (4) , characterised by that said retaining body is associated in a package (9) with a second sealing lip (8b) that is alternative and of a different yielding characteristic to said first flexible sealing lip (8a) .

2. System as in claim 1, wherein said first flexible sealing lip (8a) is made of non-marking silicone rubber.

3. A system as in claim 1 or 2, wherein said second flexible sealing lip (8b) is made of closed cell or open cell foam rubber.

4. A system as in any one of the preceding claims, wherein said flat perimeter seat (4) has two adjacent grooves, an inner and an outer groove subdivided by a thin septum, and said first flexible sealing lip (8a) has a cross-section having two adjacent rectangular portions, separated by a notch and suitable for engaging said two grooves of said perimeter seat (4) .

5. A system as in claim 4, wherein said second flexible sealing lip (8b) has a cross-section being a single rectangular shape suitable for engaging said outermost groove of said perimeter seat (4) .

6. A system as in any one of the preceding claims, wherein said handle portion (1) accommodates an automatic vacuum pump which is in fluid connection with said vacuum chamber (3) by means of passage holes (7) pierced in said base (2) .

7. A system as in any one of the preceding claims, wherein said first flexible sealing lip (8a) has shimming means in the form of a chamfered portion (8a') , on the inner side of an outermost perimeter portion, which has increasing thickness going towards the outermost perimeter area.

8. A system as in any one of claims 1 to 6, wherein said first flexible sealing lip (8a) has shimming means in the form ofa protruding section (8a' ') on an outer side of a perimeter portion .

9. System as in any one of claims 1 to 6, wherein said perimeter seat (4) has shimming means in the form of a sloping back wall (4' ) with increasing thickness towards the outermost perimeter area.

10. System as in claims 7, 8 or 9, wherein said shimming means define protruding height of said first sealing lip (8a) to a greater extent in areas further away from the centre of gravity of said perimeter seat (4) than in areas closer to the centre of gravity .

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