FI93200B - A vacuum lifter - Google Patents

Description

93200

A vacuum lifter. - Vacuum production.

The invention relates to a vacuum hoist for transferring loads having a gripping surface, the hoist having at least one suction head, the suction surface of which has a plurality of protruding annular seals to form surrounded vacuum spaces connected to a vacuum source provided with a vacuum generator, the vacuum source being connected to the outer or outer with the vacuum spaces in each case via a control valve, which valve is in each case operated by a sensor tip which, together with the control valve in question, moves in the opening direction when placed on the load and in the closing direction when the load is lifted from the top.

In this case, a multi-arrangement is also possible. The vacuum lifter can lift and move, among other things, rolls formed of a wound strip made of, for example, paper, metal, plastic or laminate, and can also grip, for example, a lying or upright roll from the end face or circumferential surface, depending on the shape of the suction head. Flat or planar pieces, such as plates, can also be moved with such vacuum lifts.

A vacuum hoist according to the preamble is described, for example, in DE-GM 8435161.6. It has a planar suction plate at the suction end, on the lower surface of which several ring seals are arranged concentrically at a distance from each other. These ring seals in each case form closed, separated vacuum spaces which, when the suction plate is lowered onto the adhesion surface intended to be transferred, form sealed ring chambers in so far as they are covered by the adhesion surface. In this case, the ring seals do not have to be circular but can be of any other shape, for example oval or angular, as long as they form a closed ring. It is also not necessary that they be nested. They may also enclose adjacent vacuum spaces or they may *; be divided into several suction plates.

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The vacuum spaces are connected via openings in the suction plate to a vacuum source with a vacuum generator, for example a vacuum pump. In connection with the vacuum lifter, a valve is arranged in each vacuum space - at least in those vacuum spaces which are arranged outside the innermost vacuum space. A sensor tip is connected to each valve, which detects the size of the load gripping surface when calculating the vacuum lifter. The sensor tips are in each case arranged in such a way that, as a result of them, only those control valves are opened, the associated vacuum space of which is completely closed when the vacuum lifter is lowered onto the gripping surface. In this way, it is ensured that only those vacuum spaces are in communication with the vacuum source which, after the load of the vacuum lifter has been lowered, form closed ring folders and into which no air can be sucked in from the side.

Suitable sensor elements are, in particular, the sensor tips, which in the suction phase rise up under the action of the load-bearing surface and in this way push up the valve plate of the control valve and thus open it. In this case, however, it has proved problematic that in each case there is a full vacuum force on the side of the valve plate and also on the sensor tip away from the vacuum space before opening. Accordingly, correspondingly strong springs must be provided which reliably press the valve plate against the valve seat and then • overcome the vacuum force. In addition, the probes must be vacuum-tight, with corresponding frictional forces. As a result of both, the movement of the sensor tip when lowering the vacuum lifter onto the load is resisted by considerable forces with the consequence that the sensor tips can damage the front surface of the load.

* In addition, the friction of the probe tips in the suction plate guides increases due to the bending of such a suction plate, in order to keep its own weight as low as possible and thus to utilize its strength close to the elastic limit. In extreme cases, this can even lead to seizures.

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The object of the invention is to develop a vacuum lifter of the type mentioned at the beginning so that the driving forces of the control valve or control valves, despite reliable sealing in the closed state, are as low as possible.

According to the invention, this object is solved in such a way that the sensor tip is connected in a compensating cylinder to a controlled compensating piston, the closing piston surface of which communicates with a vacuum source and whose opening direction of the piston surface has continuous contact with the associated vacuum space. the area of the valve plate.

With this construction, the vacuum forces acting on the valve plate and the sensor tip are equalized when the control valve is closed, because the sensor tip is affected by the same vacuum force in the closing direction, which acts on the valve plate in the opening direction and thus in the opposite direction. If the control valve opens, there is no longer a pressure difference at the valve plate. Due to the connection of the surface of the piston in the closing direction with the associated vacuum space, a pressure equalization also takes place next to the compensating piston with the consequence that there are no longer any free forces there either. For safe contact of the valve plate with the valve opening or valve seat, springs with a relatively low spring force are then sufficient. In this case, only correspondingly low forces must be overcome in order to open the valve by means of the sensor tip.

In a further development of the invention, it is provided that the control valve in each case has a valve plate in a valve rod formed hollow and open towards said vacuum space, and that the valve rod communicates with the piston surface in the opening direction of the compensating piston. In this way, this piston surface has a continuous connection to the corresponding vacuum space.

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According to the invention, it is further provided that in each case the sensor tip and the control valve are mounted in a movable manner parallel to one another and the sensor tip is connected in a form-fitting manner to the valve rod of the control valve. In this case, the valve rod and / or the sensor tip must be spring-loaded in the closing direction.

In another embodiment of the invention, it is provided that the sensor tip is transversely divided, whereby the sensor part supporting the compensating piston is mounted in a housing separate from the suction head. This has the advantage that the sensor part supporting the compensating piston can be vacuum-sealed, because the corresponding housing is not exposed to the deflections of the suction head, while the other sensor part in the suction head is detached and thus can be controlled with low friction.

The drawing schematically illustrates the invention with an embodiment example shown in vertical section. The drawing shows the left side and the middle part of the vacuum lifter 1 - the right side is omitted - with the vacuum lifter resting vertically on the upper surface 2 of the stationary paper roll 3 and having a winding sleeve 4 inside. The paper web is wound on this winding sleeve 4.

The main part of the vacuum lifter 1 is a vacuum vessel 5 which is formed circular when viewed from above. It is formed as a vacuum-tight welding structure and has a suction plate 6 at the lower interface and an upper plate 7 at the top. A central tube 8 is arranged in the central part, which forms the inner interface of the vacuum vessel 5. From the outside, the vacuum vessel 5 is bounded by a circumferential side wall 9.

* Three circular ring seals 10, 11, 12 made of elastomeric materials are arranged concentrically on the lower surface of the suction plate 6 with respect to the vertical axis in the middle of the vacuum lifter 1. Together with these ring seals 10, 11, 12 the vacuum lifter 1 rests on the upper surface 2 of the paper roll 3. diameter that it is outside the winding sleeve 4 so that through the winding sleeve 4 tl.

5 93200 cannot absorb air. Together with the outer, central annular seal 11, the inner annular seal 10 forms an annular, inner vacuum space 13. The outer annular seal 12 together with the central annular seal 11 forms a second, annular and outer vacuum space 14 separated from the innermost vacuum space 13 by a central annular seal 11. To the extent that the vacuum lifter 1 has a larger diameter, additional vacuum spaces can be arranged on the outside in a corresponding manner.

The vacuum vessel 5 communicates with the vacuum generator 16 via a vacuum line 15. The vacuum generator 16 is connected to the speed control device 17 and further has a non-return valve 18. The vacuum generator 16 keeps the vacuum vessel 5 acting as a tank at a constant vacuum.

From the vacuum vessel 5 leaves a vacuum tube 19 which leads to a three-way valve 20 which is operated electromagnetically. Connected to the three-way valve 20 is an outlet 21 - provided with a non-return valve 22 - through which a connection to the free outdoor air is established. In addition, a pipeline 23 is connected, in which a control valve 24 is arranged, and which pipeline leads to a through-pipe 25. The through-pipe 25 passes through a vacuum vessel 5 and is open to the innermost vacuum space 13.

The control valve is connected by means of a control line 26 to a measured value transducer 27, which transducer operates with a measured value receiver 28, which in turn is connected to the innermost vacuum space 13 via a measuring line 29 passing through the vacuum vessel 5.

The control line 30 shown in broken lines is further connected to the speed control device 17.

In the position of the three-way valve 20 shown, the vacuum vessel 5 communicates with the innermost vacuum space 13 through the weeping 19, the three-way valve 20, the pipeline 23, the control valve 24 and the through pipe 25. The vacuum vessel is thus under full vacuum 6 93200, the vacuum being adjusted by means of the control valve 24 to a predetermined value detected via the measuring line 29, the measured value receiver 28 and the measured value transducer 27 and further passed to the control valve 24 as a control variable.

The vacuum is also actuated by a speed control device 17.

If the vacuum in the innermost vacuum space 13 is to be removed, the three-way valve 20 is turned. In this way, the pipeline 23, the through pipe 25 and thus the inner vacuum space 13 communicate with the outside air via the non-return valve 22, i.e. the inner vacuum space 13 is aerated. At the same time, the previously connected connection between the vacuum line 15 and the pipeline 23 is broken, i.e. the vacuum remains in the vacuum vessel 5.

A hollow vacuum block 31 is arranged on the outer part of the upper plate 7 of the vacuum vessel 5. Its inner space 32 communicates with the innermost vacuum space 13 by means of a through pipe 33 passing through the vacuum vessel 5, i.e. the inner space 32 always has the same pressure as the inner vacuum space 13.

At the bottom of the vacuum block 31 there is a valve opening 34 which cooperates with the valve plate 35. The valve plate 35 is connected to a valve rod 36 which is formed hollow and open at the top and bottom. The upper end of the valve rod 36 is vent- | in a bracket rod guide 37. A second valve rod guide - not shown here - is provided at the lower end of the valve rod 36. The valve rod 36 is surrounded in the interior 32 by a pressure coil spring 38 which rests at the top on the valve rod guide 37 and below on the shoulder 39 above the valve plate 35. The valve plate 35 is thus compressed by a spring spring in the direction of the valve opening 34.

The valve opening 34 extends downwards into the filter tube 40 passing through the vacuum vessel 5, which leads to the outermost vacuum space 14. A filter 41 is provided in the filter tube 14 through which the intake air from the outermost vacuum space 14 can flow when the valve plate 35 is raised from the valve opening 34.

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Arranged on the outside next to the side wall 9 of the vacuum vessel 5, a guide tube 42 is arranged, in which - with relatively detached retention - a vertically movably mounted sensor tip 43 is mounted immediately adjacent to the outer side of the outermost ring seal 12.

Above the sensor tip 43 and its axial extension, a drive rod 44 is vacuum-sealed in the upper and lower walls of the vacuum block 31. The rod is surrounded by a coil spring 45 which exerts pressure in the interior 32 of the vacuum block 31, which generates the same spring force as the coil spring 38 of the valve rod 36. The coil spring 45 rests on the top wall of the vacuum block 31 and below and engages there in a form-fitting manner between the shoulder 39 and the valve plate 35. In this way, the valve plate 35 follows the movement of the drive rod 44.

The drive rod 44 extends at the top from the vacuum block 31 to the leveling cylinder 47 and there at the end of the rod is a leveling piston 48 which moves tightly in the leveling cylinder 47, the piston surface of which corresponds to the surface of the valve plate 35. The space above the compensating piston 48 communicates with the valve rod guide 37 via the compensating line 49. The space below the compensating piston 48 communicates with the interior 32 of the vacuum block 31 via a compensating bore 50.

Larger vacuum hoists with several external vacuum spaces are provided with a device as described above for each vacuum space, in which case the vacuum blocks are connected *. with the next closest vacuum space in each case.

In the drawing, the sensor tip 43 is in its lowest position, because the diameter of the paper roll 3 exactly corresponds to the outer diameter of the outer ring seal 12. Thus, when the vacuum lifter 1 is arranged on the paper roll 3, the valve plate 35 does not rise. In this case, 8 93200 are balanced in the opening direction of the valve plate 35 by the vacuum in the interior 32 and the vacuum forces acting on the lower surface of the compensating piston 48 are substantially equal to acts on the valve plate 35 in the opening direction. Due to this alignment, the valve plate 35 is pressed against the valve opening 34 only by the action of the coil springs 38, 45.

Normally, the diameter of the paper roll 3 does not correspond exactly to the outer diameter of the outermost ring seal 12, as shown in the drawing. If the diameter is larger, the sensor tip 43 does not move when the vacuum lifter 1 is lowered, because it protrudes less than the ring seals 10, 11, 12 even if they are slightly compressed due to the vacuum lifter's own weight until the three-way valve 20 is brought into the position shown and thus vacuumed. 13 is loaded under full vacuum, the ring seals 10, 11, 12 are compressed so strongly that the sensor tip 43 comes into contact with the upper surface of the paper roll and even protrudes.

In this case, its upper end and the lower end of the drive rod 42 contact each other and the drive rod rises with it.

By means of the fork lever 46, the valve plate 35 then rises from the valve opening 34 against the action of the coil springs 38, 45. In this way, the outermost space 14 is also made vacuum by means of a filter tube 40, a valve opening 34, a vacuum block 31 and a through-tube 33. Together with the rise of the valve plate 35, a pressure equalization takes place on the upper and lower surfaces, which would otherwise result in the vacuum force acting on the lower surface of the compensating piston 48 tending to push the drive rod 44 and thus the valve rod 36 down again. However, since the valve rod 36 is formed hollow and is connected to the compensating cylinder 47 via the compensating line 49, a vacuum also enters the space above the compensating piston 48, whereby the pressure difference initially formed disappears.

After lowering the paper roll 3 - as already described above - the inner vacuum space 13 is aerated, i.e. air enters it by using a three-way valve 20. This aeration also affects the inner space 32 of the vacuum block 31 and thus the outer vacuum space 14, since the valve plate 35 is still open. When the vacuum lifter 1 is raised, the sensor tip 43 moves out of its guide tube 42 again and the valve plate 35 and the drive rod 44 lower again under the action of the coil springs 38 and 45 until the valve plate 35 closes the valve opening 34.

The situation described above requires that the paper roll 3 have a larger diameter than in the drawing, so that the sensor tip 43 rises when the vacuum lifter is placed on the paper roll. This is not the case in the present application example, so that the sensor tip 43 remains in its downwardly projecting position. As a result, the valve opening 34 remains closed, although the outermost vacuum space 14 is covered by the upper surface 2 of the paper roll 3 and could be subjected to a vacuum. However, the inner vacuum space 13 is dimensioned in such a way that in these cases the suction force caused by it is sufficient to raise and hang the paper roll 3 so that in such a case the vacuum of the outer vacuum space 14 is not required. However, when lowering and then raising the vacuum lifter 1, a problem arises that due to the spring-out of the annular seals 11, 12 in the outer vacuum space 14, a vacuum is created, because here - in contrast to the aerated inner vacuum space 13 - no air can flow. This can lead to *. when the paper roll 3 is raised, the vacuum lifter 1 enters for some distance until the vacuum formed in the outermost vacuum space is slowly released by the air flowing through the material of the paper roll 3, thus increasing the paper roll as long as sufficient vacuum acts. The paper roll then drops uncontrollably.

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To avoid this, a compressed air generator 51 is provided, which communicates with the compressed air tank 53 via the compressed air line 52 and with the interior 32 of the vacuum block 31 via a solenoid valve 54. Usually, the solenoid valve 54 is closed. After lowering the paper roll 3 and turning the three-way valve to the aeration position, the automatic control not shown here opens the solenoid valve 54 when the pressure in the vacuum space 13 has risen to approximately free outdoor air pressure. Thus, the inner space 32 of the vacuum block 31 and the inner vacuum space 13 are pressurized through the through pipe 33. The outflow of air through the line 23 and through the three-way valve 20 in the aeration position is prevented by the non-return valve 22. The overpressure generated in the innermost vacuum space 13 is sufficient to lift the vacuum lifter 1 from the paper roll 3 and overcome the outflow of the annular seals 11, 12. In this case, there is no longer any unintentional inclusion of the paper roll 3. The supply of compressed air stops immediately after the vacuum lifter 1 has been raised, which is controlled automatically by suitable pressure sensors.

The vacuum lifter 1 is - although not shown in more detail here - suspended centrally in the lifting device. The lower roller of the hoisting device is then connected to a support pin 55, which: the pin is movably mounted on the vertical guide 57 via slate stones 56. From below the support pin 55 is spread and thus rests above the disc spring 58. A lower limit switch 59 is provided in the lower part of the vertical guide 57. end position. The limit switch 59 is connected to the three-way valve 20 by means of a control (not shown).

When the paper roll 3 is lowered, the lifting device loosens with the result that the backstones 56 together with the carrier pin 55 sink down. The use of the limit switch 59 causes the three-way valve 20 to switch from the position shown, in which the inner vacuum space 13 is under vacuum, to the aeration position, whereby the 93 93200 inner vacuum space 13 automatically comes into contact with the outside air. Another limit switch, not shown in more detail here, is connected to the lifting device to ensure the slackness of the rope and automatically disconnects the lifting device. In addition, the limit switch 59 can also be connected to the solenoid valve 54 of the compressed air generator 51 so that the inner vacuum space 13 not only simultaneously aerates but also enters compressed air. The vacuum lifter 1 can then be lifted off the paper roll 3.

The control ensures that when the rocker stones 56 leave the limit switch 59, the three-way valve 20 does not engage in the new position, but this engagement takes place only after the vacuum lifter 1 is lowered onto the second roll of paper again and thus the rocker stones 56 land on the limit switch 59. However, it is also possible to use another type of logic connection or to return the three-way valve to the vacuum position by the operator alone.

The vacuum lifter 1 further has an emergency vacuum generator 60, which is connected to the interior of the vacuum vessel 5 via an emergency vacuum line 61. The emergency vacuum generator 60 is likewise secured by a non-return valve 62. The emergency vacuum generator 60 is driven by a DC motor 63 which is connected to the battery 65 via a pressure switch 64. The battery 65 is continuously connected to the mains-connected battery charger 66 and is thus continuously stored in the best charging state.

The pressure switch 64 is connected to a measured value receiver 67, which is connected via a measuring line 68 to a vacuum vessel ·. with the interior. The measured value transducer 67 is adjusted so as to provide a closing pulse to the pressure switch 64 formed as a magnetic switch when it is determined via the measuring line 68 that the vacuum vessel 5 has fallen below a certain minimum value. This starts the DC motor 63 and thus the emergency vacuum generator 60, whereby the drop in the vacuum in the vacuum 5 is again compensated, and a normal vacuum level is reached. At the same time, 95200 12 is given a fault message via the signal sensor 69 so that the operator can know for sure that the vacuum created by the vacuum generator 16 is not sufficient to transport the paper roll 3.

The pressure switch 64 also leaves a remote control line 70, by means of which the operator can also use the pressure switch 64 independently of or as an alternative to the automation described above and thus actuate the emergency vacuum generator 60.

The drop of the vacuum can take place, for example, when the vacuum former 16 fails or also because the vacuum adhesion properties of the paper roll 3 have deteriorated to such an extent as to result in its time-dependent, viscoelastic and hydroscopic behavior that the vacuum former 16 is no longer sufficient to create a vacuum. In this case, the emergency vacuum generator 60 assists. In addition, it can be arranged that the emergency vacuum generator 60 is also switched on by the operator if this seems necessary.

In general, vacuum is to be understood in this description as a pressure lower than the pressure of the free outdoor air.

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Claims (6)

A vacuum lifting device for transferring loads with an engaging surface, the lifting device having at least one suction head, the suction surface having several projecting ring seals for forming vacuum spaces surrounded by them and connected to a vacuum source provided with a vacuum generator, the vacuum source being provided with a vacuum source. or more external vacuum spaces, in each case through a control valve, which in each case is driven by a sensing tip, which together with the relevant control valve moves in the opening direction at the position of the load and in the closing direction when lifting from the load, in each case, the sensing tip (43, 44) is coupled to a balance piston (48) guided in a balancing cylinder (47), whose piston area located in the closing direction is connected to the vacuum source (5, 60) and whose piston area located in the opening direction is continuously connected to the connecting the vacuum surface (14). 2. A vacuum lifting device according to claim 1, characterized in that the surface area of the balance piston (48) corresponds to the surface area of the control valve valve plate (35). Vacuum lifting device according to Claim 1 or 2, characterized in that the control valve in each case has a valve disc (35) located on a valve stem (36) made hollow and open to the vacuum space (14), and that the valve stem (36) is in contact with the balance piston (48) located in the opening direction of the piston. Vacuum lifting arrangement according to any one of claims 1-3, characterized in that in each case the sensing tip (43, 44) and the control valve (34, 35) are stored mutually parallel and the sensing tip (43, 44) is jointly molded with the control spindle (36) of the control valve (34, 35). 16 93200 Vacuum lifting device according to any of claims 1-4, characterized in that in each case the control valve (34, 35) and / or the sensing tip (43, 44) are spring loaded in the closing direction. Vacuum lifting device according to any one of claims 1-5, characterized in that the sensing tip (43, 44) is divided transversely, wherein the balancing piston (48) supporting the sensing part (44) is stored in a separate suction head (5) separate capsule (31) . * · T