DE29609486U1 - Vacuum holding device - Google Patents

Description

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02 May 1996 G 17 496 - lehö

Festo KG, 73734 Esslingen Vacuum holding device

The invention relates to a vacuum holding device for holding objects, with a movable carrier on which several suction units that can be subjected to vacuum are arranged, which can be displaced in mutually parallel directions independently of one another between an extended basic position and more or less retracted length compensation positions relative to the carrier and are preloaded by spring force in the direction of the extended position.

A vacuum holding device of this type is described, for example, in DE 30 18 082 A1. It is used to hold objects, especially workpieces, during transport between different locations, whereby the objects to be transported are lifted at the starting location by the vacuum holding device.

The existing multiple arrangement of suction units ensures that high holding forces can be transmitted overall, because the object to be handled is simultaneously sucked in by a plurality of suction units during suction operation of the vacuum holding device. Existing surface irregularities of the object to be held are thereby compensated for by a respective

Length compensation devices assigned to the suction unit compensate for this, whereby each suction unit is arranged on the support so that it can move in the stroke direction and is resiliently pre-tensioned into an extended basic position.

The well-known vacuum holding device is specially designed for holding flat objects. However, the well-known vacuum holding device is less suitable for lifting objects that have a very irregular or strongly curved or inclined surface, because in this case numerous suction units would be moved into far retracted length compensation positions and would not be able to transfer any load-bearing force.

It is therefore the object of the present invention to create a vacuum holding device of the type mentioned at the beginning, which enables the transmission of high holding forces even in the case of objects with a highly irregular, curved and/or inclined surface.

To solve this problem, according to the characterizing part of claim 1, it is provided that a locking device is present with which the suction units can be releasably fixed in their length compensation positions in the extension direction so that they cannot be moved relative to the carrier.

In this way, all suction units can participate in the transmission of lifting forces regardless of the relative position they assume with respect to the carrier. To grasp an object to be lifted, the carrier is moved so far to the relevant

Object is approached until all suction units opposite the object are in contact with the object's surface, whereby one or more suction units can assume the basic position and one or more further suction units can assume a more or less retracted length compensation position. The relative position assumed depends on the surface contour of the object to be lifted. As soon as all suction units are in contact with the object and are sucking it in during suction operation, the locking device can be brought into an effective position in which the suction units are releasably blocked so immovably with respect to the carrier that a displacement movement is impossible, at least in the extension direction. In this way, all suction units sucked onto the object are coupled to the carrier in the lifting direction in such a way that lifting forces acting on the carrier are transferred to the suction units and from these to the object to be lifted. In this way, not only those suction units that are in the fully extended basic position contribute to the transfer of the load-bearing force, but also all other suction units, regardless of how far they are pushed back into a more or less retracted length compensation position due to the object contour. Thus, the vacuum holding device according to the invention can be used to securely hold not only flat, flat objects, but also those with a very irregular, curved or inclined surface.

Advantageous further developments of the invention are set out in the subclaims.

Preferably, the locking device is designed such that the suction units are fixed in the active position in a force-locking manner to the carrier in such a way that no relative movement with respect to the carrier is possible in either of the two possible axial directions.

In a further advantageous embodiment, the locking device is designed in such a way that when the locking device is switched from its ineffective position, which does not block the suction units, to the effective position, which blocks them, all suction units can be locked at the same time. This enables a simple structure with reliable functionality.

The locking device is expediently designed as a clamping device. Each suction unit can be surrounded by a clamping sleeve that is fixed to the support and that firmly clamps the associated suction unit when the locking device is in the active position. The clamping sleeves can be designed like ring- or sleeve-shaped collets that coaxially surround the suction units and have radially movable clamping arms that are pressed radially against the suction units in the active position. The clamping device can have a movable actuating element that is assigned to all clamping sleeves.

Preferably, the locking device is designed as a fluid-operated device, in particular as a pneumatically operated locking device.

It is also advantageous if all suction units are connected to a common vacuum source during suction operation, whereby each suction unit preferably has a suction valve through which the suction flow is controlled depending on whether the suction chamber of the suction unit in question is covered by an object to be held or whether the suction chamber is completely or partially uncovered. This results in an air-saving function and, in addition, the vacuum applied to covered suction chambers is not weakened by uncovered suction units.

The support of the vacuum holding device can be designed as a block-like suction head in which the suction units are mounted in a very small space with tubular guide parts.

The invention is explained in more detail below with reference to the accompanying drawings, in which:

Figure 1 shows a first design of the vacuum holding device according to the invention in longitudinal section along section line I-I from Figure 2, showing a working position in which an object to be lifted is held on the vacuum holding device and the basic positions of the suction units are indicated in dash-dot lines, and

Figure 2 shows a cross section through the vacuum holding device from Figure 1 according to section line II-II.

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The vacuum holding device 1 shown in the drawing has a carrier 2 which forms a block-like suction head and which is attached to a drive device 3 which is only indicated schematically. The carrier can be moved and positioned in a desired manner by the drive device 3.
to grasp a schematically indicated object 4 at a first location, lift it and move it to another location, not shown in detail, and then deposit or release it there. The drive device 3 can have a
or several linear drives that enable multi-axis movement. In particular, the drive device enables
3 a movement of the carrier 2 in the vertical height direction,
which is indicated by double arrow 5, so that the carrier 2 can be raised or lowered as required.

A plurality of suction units 6 are arranged on the carrier 2. They have tubular guide parts 7 with which
from the underside of the carrier 12 into guide recesses 8
which are formed in the carrier 2 and are open towards the carrier underside 12. The guide parts 7 are used to slide the suction units 6, which can be moved independently of one another relative to the carrier 2 in parallel displacement directions indicated by double arrows 13.
The displacement directions 13 run in the direction of the common longitudinal axes 14 of the guide recesses 8 and the suction units 6. For example, they extend in the height direction 5.

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A large number of suction units 6 are mounted in the carrier 2, whose longitudinal axes all run parallel to one another. Figure 2 shows the distribution of the suction units 6 within a suction field 15, which extends at right angles to the longitudinal axes 14 and whose outline practically defines the working area of the vacuum holding device 1. The suction units 6 are evenly distributed within this suction field 15 in a matrix-like manner, with the smallest possible transverse distance from one another.

Each suction unit 6 has a suction cup 16 made of rubber-elastic material at the free end pointing away from the carrier 2, arranged outside the carrier 2. The suction cup 16 delimits a suction chamber 17 that is open at the bottom and is in fluid communication with a suction channel 21 that runs through the guide part 7 in the longitudinal direction. This suction channel 21 opens out into the associated guide recess 8 with its end opposite the suction chamber 17 at the end region of the guide part 7 arranged in the guide recess 8. All guide recesses 8 open out into a common vacuum distribution chamber 22 with their upper end axially opposite the associated suction unit 6, which communicates with a suction line 23 that leads to a control valve 24. Depending on the switching position of this control valve 24, the suction line 23 is connected to a vacuum source V or to the environment R. In this way, all suction chambers 17 can be either subjected to vacuum or ventilated together.

Each suction unit 6 is assigned a retaining spring 25 which pre-tensions the assigned suction unit 6 into a basic position. In Figure 1, the suction unit 26 shown on the far left assumes the basic position. The suction unit 6, 26 in question is extended as far downwards as possible from the carrier 2 so that its suction cup 6 assumes the maximum possible distance from the carrier 2. The basic position is defined by the fact that a limit stop 27 which is arranged on the end region of the guide part 7 located in the guide recess 8 rests against a counter stop 28 which projects below the limit stop 27 into the assigned guide recess 8.

As long as the suction units 6 are not yet in contact with an object 4 to be held, they all assume the basic position, in which they are preferably extended the same distance from the carrier 2. These basic positions are indicated in Figure 1 by dash-dotted lines at 31. The suction units 6 are pre-tensioned in the extension direction in the direction of the basic position by the respective associated retaining spring 25. The retaining springs 25 are preferably compression springs, which, as in the exemplary embodiment, can be designed as helical compression springs. They are preferably located in the upper section 32 of a respective guide recess 8, with one lower end being supported on the associated end region of a respective guide part 7 and their opposite upper end being supported on a support wall 33 fixed to the carrier.

For example, all retaining springs 25 are supported on a common support wall 33, which simultaneously forms an end wall of the vacuum distribution chamber 22 arranged on the upper side of the carrier. The guide recesses 8 open into the vacuum distribution chamber 22 on the underside opposite the support wall 33, with the retaining springs 25 penetrating the vacuum distribution chamber 22.

Preferably, the retaining springs 25 on the suction units β are supported on the limit stops 27.

If a pressure force F is exerted on a suction unit 6 in the area of the suction cup 16 directed towards the carrier 2, which is greater than the opposing spring force of the associated retaining spring 25, the suction unit 6 in question moves into the associated guide recess 8 while simultaneously compressing the associated retaining spring 25.

If an object 4 to be transported is to be lifted up, the vacuum holding device 1 is placed with the suction cups 16 in front on the facing object surface 34. The carrier 2 is lowered until all suction units 6 that are opposite the object surface 34 are sitting on this object surface 34. In the case of an irregular object surface 34 with surface sections of different heights, this results in the suction units 6 moving into the carrier 2 to different distances. In practice, a length compensation takes place, whereby the effective length of the suction units 6 protruding from the carrier 2 automatically

to the object profile. The positions of the suction units 6 that are retracted more or less far into the carrier 2 are therefore referred to as length compensation positions.

If the suction units 6 are spring-loaded with their suction cups 16 on the object surface 34 and the vacuum holding device is in suction mode, in which a negative pressure is generated in the suction chambers 17 as a result of the correspondingly switched control valve 24, all those suction units 6 whose suction chamber 17 is completely covered by the object surface 34 will suck themselves onto the object 4. Without additional measures, however, when the carrier 2 is subsequently lifted up, only those suction units 6 could exert a load-bearing force on the object 4 which assume the basic position and on which a lifting force acting in the lifting direction 35 is exerted by the carrier 2 due to the positive contact between the counter stop 2 8 and the associated limit stop 2 7.

However, a locking device 36 is advantageously provided, which makes it possible to releasably fix the individual suction units 6 in their respective length compensation positions with respect to the carrier in such a way that they are no longer able to carry out a relative movement to the carrier 2 in the extension direction, i.e. in the direction of the basic position. In other words, the suction units 6 can be blocked in the length compensation positions, whereby fixing is expediently possible in such a way that the suction units

units 6 are fixed immovably in both possible axial displacement directions.

In this way, all suction units 6 that are sucked onto the object 4 can be firmly connected to the carrier 2 for a desired period of time, so that a force transfer takes place between the carrier 2 and also the suction units 6 that assume a length compensation pitch in the lifting direction 35. A load-bearing force can thus be exerted on the object 4 via all suction units 6 sucked onto the object 4, so that the object can be safely lifted regardless of its irregular surface profile.

The locking device 36 implemented in the embodiment is designed as a clamping device 37, which can be switched between an inactive position and the active position shown in Figure 1. In the inactive position, the suction units 6 can be moved relative to the carrier 2. In the active position, they are locked in place with a force fit, whereby the design as a clamping device has the particular advantage that stepless clamping is possible in any length compensation position.

The clamping device 3 7 of the embodiment is designed in such a way that when switching to the active position, all suction units 6 are simultaneously fixed to the carrier. This also affects those suction units 6 that remain in the basic position. This ensures that all relevant suction units are always

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units 6. As a rule, the displacement positions of the suction units 6 when successively holding different objects 4 will vary constantly.

The clamping device 37 of the vacuum holding device 1 shown has a number of clamping sleeves 38 corresponding to the number of suction units 6. Each suction unit 6 is coaxially enclosed by such a clamping sleeve 38 in the area of its externally cylindrically contoured guide part 7. The clamping sleeves 38 according to the example are designed like sleeves in the manner of collets and have a plurality of clamping arms 42 distributed over the circumference of each guide part 7, which are formed on a common annular holding section 43 that surrounds the guide part 7 and extend axially. Between clamping arms 42 that are adjacent in the circumferential direction, there are gaps that enable a relative movement of the clamping arms 42 in the radial direction independently of one another. The arrangement according to the example is such that the clamping sleeves 3 8 are inserted with their holding section 43 in front into an enlarged section 44 of the associated guide recess 8, so that the clamping arms 42 point axially in the direction of the suction cups 6.

The clamping arms 42 of the clamping sleeves 38 extend into a control chamber 45 common to all suction units 6, which is formed in the interior of the carrier 2. This control chamber 45 is penetrated by all guide parts 7. In the control chamber 45, a preferably piston- or plate-shaped

formed actuating member 46, which is also penetrated by the guide parts 7 of all suction units 6. Sealing rings 48 are held in the area of the corresponding through openings 47, so that the suction units 6 and the actuating member 46 can be displaced relative to one another parallel to the displacement direction 13, but fluid passage through the through openings 47 is excluded.

The actuating member 46 is arranged in the control chamber 45 parallel to the displacement direction 13 in an actuating direction 52. A circumferential seal 53 arranged on the edge of the actuating member 46 seals the actuating member 46 against the side wall of the control chamber 45. On the clamping side 54 of the actuating member 46 facing the clamping sleeves 38, there are loading parts 55 assigned to a respective clamping sleeve 38, which are formed, for example, by conical end sections of the through openings 47 that widen towards the clamping side 54. Since the clamping arms 42 have loading surfaces 56 that run obliquely inwards in the area of their free end, a force-related interaction with the loading parts 55 is possible. If the actuating member 46 is moved in the direction of the clamping sleeves 38, which in turn are fixed to the carrier 2 in the same direction via the holding sections 43, the clamping arms 42 are acted upon in the area of their actuating surfaces by the actuating parts 55 in such a way that they are pressed radially inwards against the outer circumference of the guide recesses 8 and clamp around them. This

position corresponds to the effective position of the clamping device 37.

The required actuating force for the actuating member 46 is preferably provided by an actuating fluid, in particular compressed air. The actuating fluid originating from a pressure medium source P is guided as required by actuating a further control valve 57 into a pressurization chamber 58 which is delimited by the actuating member 46 in the control chamber 45. The actuating member 46 divides the control chamber 45 into two sub-chambers while sealing them, with the clamping side 54 delimiting the first sub-chamber and the pressurization chamber 58 being on the opposite side.

To release the suction units 6, the control valve 57 simply has to be switched to a venting position. As a result, the loading member 46 is moved back to an initial position by the force of one or more return springs 62, in which the loading force on the clamping arms 42 is reduced or removed. This corresponds to the ineffective position of the clamping device 37.

In order to prevent the actuating member 46, which is assigned to all suction units 6, from jamming during its movement, stroke limiting elements 63 are provided which limit the actuating stroke of the actuating member 46 to a minimum. In the exemplary embodiment, the stroke limiting elements 63 are formed by rubber-elastic elastic elements which can be constructed in the manner of rubber buffers. Several such stroke limiting elements are provided.

limiting elements 63 are present, which are preferably ring-shaped and coaxially enclose some of the guide parts 7 in the application space 58. A uniform distribution is provided, whereby in the case of a rectangular or square suction field 15 an arrangement in the corner areas is recommended, as indicated in Figure 2. The axial dimensions of the stroke limiting elements 63 are preferably selected so that the actuating member 46 resting on them in the inactive position does not or only slightly act on the clamping sleeves 38 in such a way that no significant clamping effect is exerted in relation to the guide parts 7. Only when actuating fluid is fed into the control chamber 45 does a minimal deflection of the actuating member 46 take place, resulting in a clamping effect.

With the large number of suction units 6 present, it cannot be ruled out that some of the suction chambers 17 remain open in the working position because they are not covered by the surface of the object 4 to be lifted. Without special measures, this would lead to a high loss of air and also a disturbing drop in pressure in the other suction chambers in a case where, as in the embodiment, all suction units 6 are connected to a common vacuum source during suction operation. Therefore, each suction unit 6 is preferably equipped with a suction valve 64, only indicated schematically in Figure 1, which is preferably connected in the course of the suction channel 21.

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The basic structure of this suction valve 64 can, for example, correspond to that described in DE 30 18 082 A1 or that described in DE 38 10 989 C2. The suction valve 64 expediently contains a movable valve member 65 which, when the suction cup 16 is not covered, is moved by the suction of the applied vacuum into a closed position (indicated at 66), in which the flow of air through is prevented or at least greatly reduced. In contrast, when the suction chamber is covered, the valve member assumes an open position (indicated at 67), in which the flow of air through is possible, so that the suction chamber is evacuated.

If the object 4 is to be placed at any location, it is sufficient to release the suction cups 16 by switching the control valve to the ventilation position so that the negative pressure in the suction units 6 is eliminated.

Claims (13)

02. May 1996 G 17 496 - lehö Festo KG, 73734 EsslincrenVacuum holding device claims 1. Vacuum holding device for holding objects, with a movable carrier (2) on which several vacuum-loaded
Suction units (6) are arranged which can be displaced in mutually parallel directions (13) independently of one another between an extended basic position and more or less retracted length compensation positions relative to the carrier (2) and are guided by spring force in the direction of the extended
Position are pre-tensioned, characterized in that a locking device (36) is provided with which the suction units (6) in their length compensation positions in the extension direction
immovable relative to the carrier (2) detachable fixable
are. 2. Vacuum holding device according to claim 1, characterized in
net that the locking device (3 6) is designed in such a way
that the suction units (6) in the effective position of the locking device
(36) are fixed immovably relative to the carrier (2) in both axial directions. 3. Vacuum holding device according to claim 1 or 2, characterized in that the locking device (36) is designed in such a way that when it is switched from the ineffective position enabling displacement of the suction units to the effective position preventing displacement at least in the extension direction, all suction units (6) are fixed simultaneously. 4. Vacuum holding device according to one of claims 1 to 3, characterized in that the locking device (36) is designed as a clamping device (37). 5. Vacuum holding device according to claim 4, characterized in that each suction unit (6) is surrounded by a clamping sleeve (38) fixed to the carrier (2), which allows displacement of the associated suction unit (6) in the ineffective position of the locking device (36) and is clamped radially against the associated suction unit in the effective position of the locking device (36). 6. Vacuum holding device according to claim 5, characterized in that the clamping sleeves (38) are designed in the manner of collets with radially movable clamping arms (42). 7. Vacuum holding device according to claim 5 or 5, characterized in that the clamping device (37) has a movable actuating member (46) commonly associated with all clamping sleeves (38). 8. Vacuum holding device according to claim 7, characterized in that the actuating member (46) is arranged in a control chamber (45) so as to be movable parallel to the possible displacement direction (13) of the suction units (6) and there delimits an actuating space (58) which can be actuated with an actuating fluid so that the actuating member (46) acts on the clamping sleeves (38) to produce a clamping effect. 9. Vacuum holding device according to claim 7 or 8, characterized in that the actuating member (46) is designed in the form of a piston or plate and is slidably penetrated by the suction units (6) in a sealed manner. 10. Vacuum holding device according to one of claims 1 to 9, characterized in that all suction units (6) are connected to a common vacuum source (V) in suction mode. 11. Vacuum holding device according to one of claims 1 to 10, characterized in that each suction unit (6) contains a suction valve (64) which, in suction operation, assumes an open position when the suction chamber (17) of the suction unit (6) is covered by an object (4) to be held and a closed position when the suction chamber (17) is uncovered. 12. Vacuum holding device according to one of claims 1 to 11, characterized in that the carrier (2) is arranged on a drive device (3) and is movable by this at least in the vertical direction (5), wherein the suction units (6) are located in the region of the underside of the carrier (2) and also are mounted on the support (2) so as to be movable in the vertical direction (5). 13. Vacuum holding device according to one of claims 1 to 12, characterized in that the carrier (2) forms a block-like suction head in which the suction units (6) are displaceably mounted with tubular guide parts (7).