Device for transporting workpieces

Abstract

Device for the suspended transport of workpieces (W), in particular of suspended or supported sheet-shaped workpieces (W) such as sheets, plates or foils, with at least one continuously driven conveyor belt (2) for the workpieces (W) to be placed thereon, and with a holding device (1) past which the conveyor belt (2) is guided, wherein the holding device (1) holds the workpieces (W) by generating a vacuum using a vacuum source (3) at suction openings (4) arranged laterally next to the conveyor belt (2) and / or overlapping the conveyor belt (2) on the holding device (1), and wherein an additional overpressure source (6) is provided for selectively pressurizing individual suction openings (4) in order to release the workpieces (W) from the conveyor belt (2) at least in the area of ​​a discharge point (AS), characterized in that the vacuum source (3) and the overpressure source (6) are connected to at least one rotary valve (7,8) are connected to the stator (7) and rotor (8), wherein the rotor (8) selectively connects the overpressure source (6) or the underpressure source (3) in the stator (7) to the intake opening (4) via at least one bore (12, 13) and associated lines (14, 15) in the stator (7).

Description

[0001] The invention relates to a device for transporting workpieces, in particular hanging or lying panel-shaped workpieces such as sheets, plates or foils, with at least one continuously driven conveyor belt for the workpieces to be placed thereon, and with a holding device past which the conveyor belt is guided, wherein the holding device holds the workpieces by generating a vacuum using a vacuum source at suction openings arranged laterally next to the conveyor belt and / or overlapping the conveyor belt on the holding device, and wherein an additional overpressure source is provided for selectively pressurizing individual suction openings in order to release the workpieces from the conveyor belt at least in the area of ​​a discharge point.

[0002] The terms overpressure source and underpressure source refer to a source of air that creates a corresponding underpressure or overpressure relative to normal atmospheric pressure (typically around 1 bar). The magnitude of the pressure difference depends on the size and weight of the sheet-shaped workpieces being transported. It also depends on the design of the system. For example, both the underpressure and overpressure can vary from several millibars above normal pressure up to one bar or even more.

[0003] In fact, the suction openings can be arranged laterally next to the conveyor belt, so that, for example, two conveyor belts with central suction openings are guided past the holding device. This is the approach taken, for example, in the prior art according to DE 20 2010 013 140 U1, which is attributed to the applicant.

[0004] In this context, the respective suction opening can be selectively activated or deactivated depending on the workpiece's position relative to the holding device. This allows for sequential control such that, depending on the number of suction openings covered by the workpiece, all or selected covered suction openings are pressurized with negative pressure. For this purpose, each suction opening is equipped with its own valve for negative pressure control.

[0005] For this purpose, a closing device can be assigned to each intake opening, which is actuated individually or in groups by a control unit. The closing device can rotate around an axis and have at least one actuating leaf. This has proven effective in principle, but is technologically complex, especially since it only uses a vacuum source. As a result, targeted ejection of the workpieces at a designated ejection point is difficult to achieve and implement.

[0006] EP 0 827 919 A2 relates to a belt conveyor for the suspended transport of goods using negative pressure. At least one discharge point features a separately controllable negative pressure element. This negative pressure element can be applied to or decoupled from a vacuum in the transport path prior to the discharge point, independently of any additional negative pressure device provided. This ensures that the items conveyed successively by the conveyor belt are always deposited uniformly and at the correct time. The aim is to enable the discharged sheets to be stacked neatly on a pallet positioned below the discharge point without the need for complex straightening units.

[0007] In a device for transporting flat goods according to DE 10 2009 019 785 B4, an intake channel is provided that is open at least over a section of its longitudinal extent. The intake channel is equipped with openings along its longitudinal extent that communicate with vacuum ports in the associated conveyor belt. In this case, the vacuum holding device is designed as an activatable and deactivatable vacuum holding device for holding or releasing the goods. The vacuum source is at least one fan.

[0008] In the generic and therefore closest prior art according to DE 101 04 510 B4, which originates from the applicant, the holding device works by creating a controlled or regulated vacuum that holds the sheet-shaped workpieces against suction openings located next to the conveyor belt. In addition to the suction openings, discharge openings are provided, which can be selectively activated to vary the vacuum between the workpiece and the conveyor belt and are supplied with adjustable compressed air overpressure. This already provides a precise discharge of the workpiece. The suction openings are acted upon by a so-called ejector as the vacuum source. Its discharge openings provide the necessary overpressure. In other words, the vacuum source and the overpressure source coincide, so to speak.

[0009] The aforementioned prior art according to DE 101 04 510 B4 has proven effective when the primary objective is the precise discharge of sheet-shaped workpieces transported by a driven conveyor belt at a single discharge point. However, this requires a large number of switchable valves. Such valves are susceptible to malfunctions during frequent switching and continuous operation. The invention aims to remedy this problem.

[0010] The invention is based on the technical problem of further developing such a device for transporting workpieces in such a way that a permanent functional operation is provided while realizing an unchanged flawless ejection of the workpieces at the desired ejection point.

[0011] To solve this technical problem, a generic device within the scope of the invention is characterized in that the vacuum source and the pressure source are connected to at least one rotary valve with stator and rotor, wherein the rotor selectively connects the pressure source or the vacuum source to the intake opening via at least one bore and associated lines in the stator.

[0012] According to the invention, a special valve, or several such special valves, are used, namely the rotary valve with stator and rotor. Such rotary valves are generally known, but in a different context. Reference is made to EP 1 613 952 B1 by way of example.

[0013] Rotary valves are characterized by the fact that switching operations are achieved and implemented through the rotation of a rotor relative to a stationary stator. This allows for particularly low wear, while maintaining the necessary functionality even over extended periods. In contrast, conventional valves with a piston and associated seat tend to experience wear with frequent actuation and over long periods, which is significantly lower in rotary valves due to their different movement. This enables extremely long service lives in practice, especially with frequent switching operations. This is particularly important in the context of transporting and precisely dispensing numerous sheet-like workpieces. These are the key advantages.

[0014] To implement this in detail, the rotor typically has two bores. It has proven particularly advantageous for the two bores to be diametrically opposed to one of the rotor's rotational axes. Each bore is typically designed as a two-part axial bore that leads into a radial bore. The radial bore, in turn, usually extends to the outer circumference of the rotor.

[0015] In this way, the bore in the rotor can easily communicate with a conductor in the stator, depending on the rotor's position. That is, as soon as the bore in the rotor aligns with the corresponding conductor in the stator and can therefore communicate, the negative or positive pressure typically present at the bore is transferred to the conductor in question in the stator and then passed on to the intake port, usually located at the end of the conductor, or to the multiple intake ports, depending on the design.

[0016] To implement the various positions of the rotor and, optionally, the overlap of the bore with the conductor in the stator, and thus the switching process, the rotor is generally coupled to a drive shaft. The drive shaft defines the axis of rotation of the rotor relative to the stationary stator. Furthermore, the drive shaft is largely perpendicular to the disc-shaped rotor. The disc-shaped rotor and the drive shaft can, in principle, form a single unit or even be manufactured as a single piece.

[0017] The rotor is generally rotatably mounted in a hollow bore of the stator. This allows the rotor to divide the predominantly cylindrical hollow bore of the stator into two separate chambers. Typically, one chamber of the stator's hollow bore is connected to the negative pressure source, while the other chamber is connected to the positive pressure source. Furthermore, the two chambers are usually sealed against each other.

[0018] In this way, for example, the chamber connected to the vacuum source, the vacuum chamber, can communicate with the associated intake port line when the rotor assumes a position in which the bore or line leading into the vacuum chamber is aligned with the radial bore extending to the outer circumference of the rotor. This is because the vacuum inside the vacuum chamber then ensures that the associated line is also pressurized, and consequently, so is the intake port located at the end of the line.

[0019] The design is further configured such that one bore of the rotor communicates with the negative pressure chamber, and the other bore communicates with the positive pressure chamber. As a result, the two axial bores of these bores run in opposite directions. This will be explained in more detail with reference to the figure description. In any case, the bore of the rotor connected to the negative pressure chamber communicates with the intake port line in a specific rotor position, thus pressurizing the corresponding intake port. This is usually achieved by having the radial bore, extending to the outer circumference of the rotor, communicate with an arc opening that forms part of the line inside the stator. This arc opening inside the stator may be designed as a semicircular arc opening. Typically, two semicircular arc openings are provided in the stator, connected to each other via a seal.

[0020] In this way, the bore in the rotor connected to the negative pressure chamber can supply the line connected to the semicircular arc opening with negative pressure for the entire duration of the rotor's rotation. As the rotor continues to move, the subsequent semicircular arc opening ensures that the bore connected to the positive pressure chamber then applies positive pressure to the line connected to that semicircular arc opening.

[0021] This allows for the arrangement of multiple rotors within a single stator housing. Furthermore, it has proven advantageous in this context to drive the rotors via a common drive shaft. Additionally, the rotors can be coupled with an offset rotation. This effectively creates a linear movement of the vacuum or pressure at the connected intake ports along the longitudinal direction of the holding device equipped with these ports.

[0022] Depending on the rotational offset of the rotors during their mutual coupling, the system can accommodate varying dimensions of the transported plate-shaped workpiece, as well as the resulting parabolic discharge path at the desired point. The design is typically such that the conveyor belt, with the workpieces attached to it, reaches the discharge area by initially holding the workpieces in place at the suction openings using negative pressure. As the conveyor belt moves, individual suction openings are then pressurized, causing first a front edge of the plate-shaped workpiece and then the entire workpiece to be progressively released from the conveyor belt, thus creating the desired parabolic discharge path. This is where the key advantages lie.

[0023] The invention will now be explained in more detail with reference to a drawing that illustrates only one embodiment; the drawing shows: Fig. 1 a schematic side view of a device according to the invention, Fig. 2 the device according to the Fig. 1 in the area of ​​a drop-off point and Fig. 3 and Fig. 4 the discharge point with the rotary valve provided there in a front view ( Fig. 3) and in one cut ( Fig. 4).

[0024] The figures depict a device for transporting workpieces W. Fig. Figure 1 shows that the workpieces W in question are transported suspended. This is, of course, only an example and should not be understood as a limitation, because in principle, the workpieces W can also be transported lying flat on at least one continuously driven conveyor belt 2. For this purpose, the conveyor belt 2 is guided past a holding device 1 for the workpieces W to be placed on it. This is implemented by guiding and driving the conveyor belt 2 via drive wheels provided at each end of the holding device 1. These may be gears, and consequently, the conveyor belt 2 may be a toothed belt conveyor belt. In this exemplary embodiment, the workpieces W are sheet-shaped workpieces, in particular plates, films, but also sheets.

[0025] The transport of the tablet-shaped workpieces W takes place within the framework of the representation according to the Fig. 1 hanging, specifically in the longitudinal direction L of the holding device 1. This occurs starting from a transfer point ÜS in the left part of the Fig. 1 to a drop-off point AS in the right part of the Fig. 1, which is additional and enlarged in the Fig. Figure 2 shows that the individual workpieces W may be placed on a stack or otherwise. For this purpose, the workpieces W describe a path in the area of ​​the drop point AS in the Fig. 2. Drop parabola indicated by an arrow.

[0026] The holding device 1, by generating a vacuum using a vacuum source 3, ensures that the workpieces W are positioned against the conveyor belt 2. In the example shown, several vacuum sources 3 are implemented. However, it is also possible to have only a single vacuum source 3, which applies vacuum to the holding device 1, designed as a hollow chamber profile, although this is not shown. According to the exemplary embodiment, and without limitation, two conveyor belts 2 are implemented, enclosing between them a series of suction openings 4, which are incorporated into the holding device 1, designed as a hollow chamber profile. The hollow chamber profile is connected to the vacuum source 3 and is consequently subjected to vacuum. This, too, is only an example.For the suction openings 4 facing the conveyor belts 2 inside the holding device 1 can just as easily communicate with corresponding suction openings in the conveyor belt 2, specifically if the conveyor belt 2 with its suction openings is moved past the suction openings 4 in the holding device 1 in the longitudinal direction L, i.e., with overlap. In addition, it is also fundamentally possible that the sheet-shaped workpieces W can be additionally held by means of [something] only in the [something]. Fig. 1 indicated switchable magnetic devices 5 are held in place on the conveyor belt 2.

[0027] That is, the holding device 1 holds the workpieces W in place by generating a vacuum using the vacuum source 3, according to the exemplary embodiment, at the suction openings 4 arranged laterally next to the conveyor belt 2 on the holding device 1. Alternatively or additionally, it is also possible for the holding device 1 to ensure that the workpieces W are held in place by means of suction openings 4 arranged on the holding device 1 with overlap to the respective conveyor belt 2. In this case, the conveyor belt 2 is additionally equipped with suction openings in the conveyor belt 2, in addition to the suction openings 4 provided in the holding device 1.

[0028] Of particular importance for the invention is the fact that, in addition to the negative pressure source 3, a positive pressure source 6 is also implemented and provided. In principle, several negative pressure sources 3 and several positive pressure sources 6 can also be implemented, as indicated by corresponding arrows in the figures (see Figure 1). Fig. 2) Furthermore, it is within the scope of the invention if the respective negative pressure source 3 and the positive pressure source 6 coincide. This is realized, for example, when a so-called ejector is used as the negative pressure source 3. Such an ejector not only functions as a negative pressure source 3, but also releases positive pressure on its outlet side and can therefore additionally function as a positive pressure source 6, as described, for example, in the generic prior art according to DE 101 04 510 B4 of the applicant. Of course, any other types of negative pressure sources 3 and positive pressure sources 6 are also possible and are covered by the invention.

[0029] Of particular importance is the fact that the negative pressure source 3 and also the positive pressure source 6 are connected to at least one detail in the Fig. 3 and Fig. The rotary valve 7, 8 shown in Figure 4 is connected to the intake port 4 and performs individual switching operations at the respective intake port 4. In practice, the rotary valve 7, 8 is usually configured to supply, for example, two adjacent or spaced intake ports 4 on its output side. For this purpose, lines 14, 15 are connected to the single or multiple intake ports 4 in the rotary valve 7, 8 or its stator 7. However, it is also possible to connect only one intake port 4 to it.

[0030] For this purpose, the rotary valve 7, 8 consists of the stator 7 and a rotor 8 rotating therein about an axis or axis of rotation A. To realize and implement the rotation of the rotor 8 relative to the stationary stator 7, a drive shaft 9 is provided, which simultaneously defines the axis of rotation A of the rotor 8. Furthermore, the illustration in the Fig. 3 and Fig. 4, that the rotor 8 is disk-shaped and the drive shaft 9 runs mostly perpendicular to the disk-shaped rotor 8. In fact, the design is further such that the rotor 8 and the drive shaft 9 define a single unit 8, 9 and can even be formed as one piece, which of course is only an example and not mandatory.

[0031] The rotor 8 is mounted in a hollow bore 10a, 10b of the stator 7. The bore 10a, 10b of the stator 7 is effectively divided into two separate chambers 10a, 10b by the rotor 8. One chamber 10a is connected to the positive pressure source 6, while the other chamber 10b is connected to the negative pressure source 3. Thus, one chamber 10a is configured as a positive pressure chamber 10a, while the other chamber 10b is a negative pressure chamber 10b.

[0032] When comparing the Fig. 3 and Fig. Figure 4 shows that the two chambers 10a, 10b are sealed against each other. This is achieved by one or two seals 11, each of which may be designed as a circular seal. Furthermore, it can be seen that the rotor 8 is equipped with two bores 12, 13. According to the exemplary embodiment, the bores 12, 13 are each formed in two parts, namely each has an axial bore 12a, 13a and a radial bore 12b, 13b adjoining it. The respective radial bore 12b, 13b extends to the outer circumference of the rotor 8. In contrast, the respective axial bore 12a, 13b, as part of the bore 12, 13, opens into the corresponding chamber 10a, 10b.

[0033] It can be seen that the axial bore 12a opens into and communicates with the positive pressure chamber 10a. In contrast, the axial bore 13a of the second bore 13 is connected to the negative pressure chamber 10b. This is possible and designed this way because the two axial bores 12a and 13a each run in the axial direction of the disk-shaped rotor 8, but in opposite directions. In this way, the respective bore 12a, 13 in the rotor 8 can communicate with the line 14, 15 in the stator 7, depending on the position of the rotor 8 inside the hollow chamber 10a, 10b.

[0034] The lines 14, 15 are connected at one end to a common intake opening 4, or, according to the exemplary embodiment, to individual intake openings 4. For this purpose, two additional curved openings 14a, 15a are provided in the stator 7, into which the lines 14, 15 open at their respective ends. Curved opening 14a and curved opening 15a are each designed as semicircular curved openings. Furthermore, the design is such that curved opening 14a opens into or communicates with line 14, whereas curved opening 15a is connected to the other line 15 in the stator 7.

[0035] In this way, the respective radial bore 12b, extending to the outer circumference of the rotor 8, is connected to the semicircular arc opening 14a and thus to the overpressure source 6 when, in the illustrated example, the rotor 8 with its associated bore 12 sweeps out the upper semicircle with respect to the axis A. If, on the other hand, the rotor 8 completes a lower semicircle with respect to the axis A, the semicircular arc opening 14a and thus also the line 14 connected to it are not subjected to the associated overpressure Ü or overpressure source 6, but to the underpressure source 3 or underpressure U. The described positions and configurations can, of course, also be interchanged.The crucial point is that, depending on the position of the rotor 8, the connected intake opening 4 is selectively supplied with either negative pressure U or positive pressure Ü via the associated line 14, 15, whereby the positive pressure Ü can also run into empty space and in this case the intake opening is only supplied with negative pressure U via a semicircular cycle of the rotor 8.

[0036] That is, the vacuum source 3 and the pressure source 6 are not only connected to the at least one rotary valve 7, 8 with stator 7 and rotor 8. Rather, the rotor 8 connects, via the at least one bore 2, 3, either the pressure source 6 or the vacuum source 3 to the respective intake opening 4, interposed by the associated lines 14, 15 in the stator 7, as will be explained in more detail below.

[0037] Returning to the Fig. 3 and Fig. Figure 4 shows that the two chambers 10a, 10b, i.e., the overpressure chamber 10a and the underpressure chamber 10b, are not only sealed against each other by means of a circumferential seal 11. The two arc openings or semicircular arc openings 14a, 15a are also separated from each other by partition walls 16. Since the two semicircular arc openings 14a, 15a are diametrically opposed with respect to the axis or axis of rotation A of the rotor 8, this also applies to the two partition walls 16. As a result, the intake opening 4, which communicates, for example, with line 14, is subjected to overpressure Ü (or underpressure U) within the stator 7 for half a rotation of the rotor 8, as shown in the Fig. 2 is shown schematically on the left. During the further half rotation of the rotor 8 inside the stator 7, one of the adjacent further intake openings 4 in the longitudinal direction L may be subjected to the negative pressure U (or positive pressure Ü) within the line 15.

[0038] This makes it generally possible to use several of the features listed in the Fig. 3 and Fig. The four rotors 8 shown are arranged in a common housing of the stator 7. The individual rotors 8 are typically coupled to one another via a common drive shaft 9 and are driven together by it. For this purpose, the individual rotors 8 can be mechanically coupled to one another with an offset in rotation. In this way, a moving motion of the negative pressure U or the positive pressure Ü can be generated at the connected intake openings 4.

[0039] This is a very general and schematic approach. Fig.2 is represented by arrows, with the upward-pointing arrows U1, U2, and U3 each indicating a progressive negative pressure in the longitudinal direction L, whereas a progressive positive pressure Ü1, Ü2, and U3 is subsequently observed. Thus, when the workpiece W moves along the longitudinal direction L in the area of ​​the discharge point AS implemented in this way, the workpiece W, moving in the longitudinal direction L, detaches from the associated conveyor belt 2 starting at its leading edge and is discharged and stacked along the discharge parabola indicated by an arrow there.

[0040] In this context, the speed of the traveling motion can be determined by a suitable motor or servomotor, which drives the drive shaft 9. Alternatively, the electric motor in question can be connected to the drive shaft 9 via an adapter, allowing for flexibility in its design. In this case, the individual rotors 8 can be coupled to each other in a rotationally fixed manner via axially extending lugs. It is understood that a rotational offset can be specified between each adjacent rotor 8, corresponding, for example, to an angle of 18° if a total of twenty rotors 8 are to be combined.In this system, ten rotors 8 are jointly responsible for generating negative pressure U and ten rotors 8 for generating positive pressure Ü, in the previously described wandering motion, which is determined by the rotational offset in the longitudinal direction L. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 20 2010 013 140 U1

[0003] EP 0 827 919 A2

[0006] DE 10 2009 019 785 B4

[0007] DE 101 04 510 B4 [0008, 0009, 0028] EP 1 613 952 B1

[0012]

Claims

[1] Device for the suspended transport of workpieces (W), in particular of suspended or supported sheet-shaped workpieces (W) such as sheets, plates or foils, comprising at least one continuously driven conveyor belt (2) for the workpieces (W) to be placed thereon, and comprising a holding device (1) past which the conveyor belt (2) is guided, wherein the holding device (1) holds the workpieces (W) by generating a vacuum using a vacuum source (3) at suction openings (4) arranged laterally next to the conveyor belt (2) and / or overlapping the conveyor belt (2) on the holding device (1), and wherein an additional overpressure source (6) is provided for selectively pressurizing individual suction openings (4) in order to release the workpieces (W) from the conveyor belt (2) at least in the area of ​​a discharge point (AS). characterized by, that the vacuum source (3) and the pressure source (6) are connected to at least one rotary valve (7, 8) with stator (7) and rotor (8), wherein the rotor (8) selectively connects the pressure source (6) or the vacuum source (3) via at least one bore (12, 13) in the stator (7) to the intake opening (4) via associated lines (14, 15). [2] Device according to claim 1, characterized by , that the rotor (8) is equipped with two bores (12, 13). [3] Device according to claim 2, characterized by , that the bores (12, 13) are diametrically opposed with respect to an axis of rotation (A) of the rotor (8). [4] Device according to any one of claims 1 to 3, characterized by , that the bore (12, 13) is formed in 2 parts with axial bore (12a, 13a) which leads into a radial bore (12b, 13b). [5] Device according to claim 4, characterized by, that the radial bore (12b, 13b) extends to the outer circumference of the rotor (8). [6] Device according to any one of claims 2 to 5, characterized by , that the bore (12, 13) in the rotor (8) communicates with the line (14, 15) in the stator (7) depending on the position of the rotor (8). [7] Device according to any one of claims 1 to 6, characterized by , that the rotor (8) is coupled to a drive shaft (9). [8] Device according to claim 7, characterized by , that the drive shaft (9) defines the axis of rotation (A) of the rotor (8) and runs mostly perpendicular to the disk-shaped rotor (8). [9] Device according to any one of claims 1 to 8, characterized by , that the rotor (8) is rotatably mounted in a hollow bore (10a, 10b) of the stator (7). [10] Device according to claim 9, characterized by , that the rotor (8) divides the hollow bore (10a, 10b) into two separate chambers (10a, 10b). [11] Device according to claim 10, characterized by , that one chamber (10a) is connected to the overpressure source (6) and is designed as an overpressure chamber (10a), while the other chamber (10b) is a negative pressure chamber (10b) connected to the negative pressure source (3). [12] Device according to claim 10 or 11, characterized by , that the two chambers (10a, 10b) are sealed off from each other. [13] Device according to any one of claims 1 to 12, characterized by , that several rotors (8) are arranged in a common housing of the stator (7). [14] Device according to claim 13, characterized by , that the rotors (8) are driven via a common drive shaft (9). [15] Device according to claim 13 or 14, characterized by , that the rotors (8) are coupled to each other in a rotationally offset manner in order to generate a wandering movement of the negative pressure or the positive pressure at the connected intake openings (4).

Images