Conveyor belt for transporting workpieces

Abstract

Conveyor belt (2) for the transport of workpieces (1), in particular for the lying transport of panel-shaped workpieces (1) such as metal sheets, plates or foils, with a belt body (13) with suction openings (12) which communicate with a vacuum channel (11) in a holding device (4), wherein the conveyor belt (2) with the workpieces (1) to be placed thereon is guided past the holding device (4) in the transport direction (T) and the workpieces (1) are held on the conveyor belt (2) by generating vacuum in the vacuum channel (11) and thus at the suction openings (12) and are moved together with the conveyor belt (2) in the transport direction (T), characterized in that the respective suction opening (12) is designed as a punching opening (12) passing through the belt body (13).

Description

The invention relates to a conveyor belt for the transport of workpieces, in particular for the resting transport of sheet-like workpieces such as metal sheets, plates or foils, having a belt body with suction openings which communicate with a vacuum channel in a holding device, wherein the conveyor belt with the workpieces to be placed thereon is guided past the holding device in the transport direction and the workpieces are held on the conveyor belt by generating vacuum in the vacuum channel and thus at the suction openings and are moved together with the conveyor belt in the transport direction.Such conveyor belts for transporting workpieces are described, for example, in the patent EP 0 893 371 B1 which is assigned to the assignee of the present invention. A comparable conveyor belt is the subject matter of German laid-open specification DE 30 01 531 A1. In the latter case, circular elevations are provided in each case opposite a core layer as a belt body. The respective elevation encloses an aperture as suction opening, which penetrates the belt body and produces a vacuum connection.Moreover and independently thereof, WO 2021 / 089315 A1 discloses a device for transporting preferably tabular workpieces, in particular on the surface, by means of reduced pressure. The negative pressure is generated by at least one blower. As a result, slipping of the workpieces can be avoided with little outlay even in the case of strong accelerations and decelerations with respect to the conveyor belt.In addition to the transport of sheet-like workpieces such as sheet metal blanks, steel plates, etc., such devices are used, inter alia, when so-called bipolar plates are to be transported. Bipolar plates are a key element of direct methanol fuel cells. To this end, the bipolar plates in question ensure not only an electrical connection of the fuel cells and the distribution of the gases over the plate surface, but also gas separation between adjacent cells, cooling and sealing to the outside.A conveyor belt of the generic type is described in the context of DE 20 2021 105 990 U1 generally in a goods device for the transport of sheet-shaped elements and a corresponding transport unit. For this purpose, the belt or conveyor belt there has a plurality of through-openings on a protruding section, the position of which is aligned with through-openings made in the belt. The through-openings are those which are designed as elongated holes. This provides a significant suction surface in order to be able to hold the tabular workpieces which are sucked firmly thereon securely.The prior art has proven itself in principle, but still offers room for improvements. This is because in the generic teaching according to DE 20 2021 105 990 U1, passage openings of different sizes are used. This complicates the production and results in increased costs. In addition, such openings are usually milled into the belt body of the conveyor belt. Although such a milling process can be realized and implemented mechanically, it is time-consuming and thus costly. The invention seeks to provide a remedy here overall.The invention is based on the technical problem of further developing such a conveyor belt for transporting workpieces in such a way that the production costs are significantly reduced compared to previous procedures.To solve this technical problem, a conveyor belt of the generic type for transporting workpieces is, within the scope of the invention, characterized in that the respective suction opening is designed as a punching opening passing through the belt body.The invention thus refers to a specially designed suction opening. The suction opening is known to communicate with the vacuum channel in the holding device. As a result, negative pressure applied to the negative pressure channel can be provided via the suction opening in order in this way to be able to hold the tabular workpiece applied to the suction opening on the conveying belt together with the conveying belt in the conveying direction during transport.Because, according to the invention, the suction opening is designed as a punching opening, the conveyor belt can be produced particularly easily, quickly and cost-effectively. This is because the suction opening is introduced into the belt body by means of a punching tool that determines its shape. Similar to sheet metal punching, for example, the punching tool consequently ensures that in one stroke in the punching operation in question the suction opening is defined as a punching opening. In this process, the procedure is simultaneously such that the punching opening reaches through the entire belt body, thus corresponding to a three-dimensional bore with a constant cross section, the punching opening.The size and shape of the inserted punching tool can consequently be used to define the punching opening. In addition, such a punching opening can easily be introduced into the belt body because it is usually made of plastic-like the conveying belt as a whole-and is realized, for example, by an extrusion process. It is understood that the punching opening passing through the belt body can be introduced into the belt body in question as a respective suction opening with the aid of an associated punching tool, wherein in this case the belt body is moved along the longitudinal direction under the punching tool in question and the respective suction openings are introduced into the belt body at predetermined intervals with the aid of the punching tool.However, it is also possible for a plurality of punching tools to penetrate simultaneously into the belt body in the longitudinal direction thereof and in this way to define a plurality of suction openings in the conveyor belt, said suction openings being configured as punching openings, depending on the number of punching tools. This thus leads to reduced production costs and at the same time to the suction opening in question being produced particularly precisely. This is because, in comparison with a milling process carried out hitherto, punching openings are distinguished by a sharper edge, in contrast, so that overall and according to the invention, a lower loss rate of, for example, sucked-in air can be expected when the tabular workpiece is in contact.These advantages are particularly obtained when the punching opening is designed as an elongated hole punching opening. In this case, therefore, a suction opening, which is for example circular disc-shaped, is not realized, but rather an elongated opening with a cross section that is usually elliptical to oval. Moreover, in this context, it is regularly proceeded in such a way that the elongated slot opening has a longitudinal extension oriented transversely to the transport direction of the workpieces and the vacuum channel.On the one hand, this provides a particularly large suction cross section for the table-shaped workpieces placed on or on top. On the other hand, this suction cross section extends transversely to the transport direction and thus also transversely to the vacuum channel in the holding device, so that a panel-shaped workpiece placed on the conveyor belt is subjected to vacuum, as seen almost over the entire width of the conveyor belt. This leads to a particularly effective adhesion of the tabular workpiece to the conveyor belt, so that, for example, large accelerations and decelerations of the conveyor belt are possible and, accordingly, the tabular workpieces can be transported not only at high speed with the aid of the conveyor belt according to the invention, but also high cycle numbers are achieved in connection with the transport of the workpieces in question from one processing station to the next.The belt body is furthermore advantageously antistatic and transparent. In order to achieve this in detail, the belt body can be equipped, for example, with embedded carbon particles or other electrically conductive particles in the interior, which particles dissipate any electrostatic charge during transport along the holding device, for example into the holding device or else in some other way.Since the belt body is typically made of plastic, transparent plastics can be used at this point. Here, PVC (polyvinyl chloride) and / or polyurethanes (PU) have proven particularly advantageous by way of example and not by way of limitation. In addition, the design is usually such that the belt body is equipped with tension members running in the longitudinal direction in the form of threads made of polyamide, for example. With the aid of these tension members, the conveyor belt or its belt body is stabilized and it is also possible to realize and implement long lengths of such conveyor belts without significant slack. This is advantageous in that the conveying belt is guided past the holding device in the transport direction. In this case, the conveying belt is usually designed as a toothed belt conveying belt which is guided via respective end-side gearwheels, i.e. gearwheels which are mounted on the end side of the holding device and ensure the drive of the conveying belt or toothed belt conveying belt.In this context, it has proven to be particularly favorable if the tension members are formed as components of a fabric embedded in the belt body. In this case, the tension members may be warp threads of the fabric in question. The fabric itself is advantageously made of polyamide. As a result, the polyamide fabric in question embedded in the belt body can be used not only for stabilizing the conveyor belt, but at the same time the desired antistatic effect can be achieved as a result, and indeed without, for example, conductivity particles additionally being introduced into the belt body during the production process or during the course of the extrusion. Rather, the polyamide fabric in question completely or partially takes over the function of these conductivity particles and ensures that any electrostatic charges are dissipated.The invention also relates to a vacuum device for transporting sheet-like workpieces, which is equipped with the holding device in question and with the conveyor belt already described above. The holding device can be designed as a hollow chamber or can have such a hollow chamber.This makes it possible to additionally fit one or more magnet holding elements inside the holding device or the hollow chamber. These magnet holding elements can be used alternatively or additionally to transport magnetizable tabular workpieces. That is, the magnet holding elements serve, in addition to the vacuum generated, for the purpose that the tabular workpieces, which can be magnetized in this case, are held not only by vacuum, but additionally electromagnetically in contact with the conveying belt. In addition, with the aid of the magnet holding elements, it is also possible to avoid any slack in the conveyor belt during its movement along the holding device. For this purpose, the tension carriers introduced into the belt body can alternatively be designed as steel cables which are magnetizable and are consequently attracted electromagnetically by the magnet holding elements placed in the interior of the holding device. Any sagging of the conveyor belt along the holding device is thereby avoided.As a rule, however, the tabular workpieces are held in contact with the conveyor belt merely by reduced pressure. For this purpose, at least one vacuum unit is connected to the holding device. The vacuum unit can be one or more vacuum blowers, as has already been described above.It has also proved to be useful if the holding device is equipped internally with at least one lighting unit. The illumination unit is usually provided at the head side of the holding device. As a result, the illumination unit is able to irradiate and advantageously irradiate the conveying belt guided along it. This applies in particular to the case where the conveying belt is transparent and made of a transparent plastic, for example.The lighting unit is generally at least one LED light bar. The LED light bar has a predetermined longitudinal and / or transverse extent for this purpose. In this way, an image recording device can be placed opposite the LED light bar. The image recording device is, for example, a camera which visually captures the conveyor belt irradiated by the light of the light bar and / or the tabular workpieces transported thereon. This can be done in the sense of a continuous video film or on the basis of individual recordings.By means of this imaging detection of the conveyor belt and / or of the tabular workpieces, it is possible not only to perform quality and function control of the conveyor belt during operation. The tabular workpieces transported with the aid of the conveyor belt can also be subjected to a quality test, for example, as to whether they have damage, adhering dirt, etc. Depending on the result of this quality check, there is then the possibility of ejecting or lifting individual sheet-like workpieces in a targeted manner from their contact on the conveyor belt, so that it is ensured that only workpieces which have previously completed the quality check are transported, for example, to the next processing station.As a result, a conveyor belt for transporting workpieces and an associated holding device are described and protected, which are distinguished by particularly low production costs and troublefree operation. This can be substantially attributed to the fact that the respective suction opening in the conveyor belt is designed as a punching opening passing through the belt body. As a result, a particularly precisely manufactured suction opening is observed, which, when the sheet-like workpiece is resting, practically does not tend to suck in any incorrect or incorrect air.This reduces the energy consumption of the vacuum unit used.At the same time, the relevant tabular workpieces bear perfectly against the conveyor belt, so that high speeds of the conveyor belt can be realized with great accelerations and decelerations. This allows the cycle number during transport to be increased compared to previous procedures.Finally, there is also the possibility that the conveying belt or belt body is ground on its surface provided for the plate-shaped workpieces or is also provided with a lacquer. By means of such a ground surface or surface equipped with a paint, the conveyor belt can be cleaned particularly easily and perfectly during operation. This is because these measures close any pores on the surface, so that inevitable contamination can be removed particularly effectively from the surface of the conveyor belt in this way and the cleaning of the conveyor belt is simplified. The essential advantages can be seen here.The invention is explained in more detail below with reference to a drawing which merely represents an exemplary embodiment; it shows: FIG. 1 shows the conveying belt according to the invention in conjunction with a vacuum device equipped therewith in a perspective illustration, FIG. 2 shows the conveyor belt in a top view, and FIG. 3 shows a schematic cross section through the conveying belt according to FIG. 2 in the region of a suction opening.FIG. 1 shows a vacuum device for transporting tabular workpieces 1, in particular resting thereon, with the aid of vacuum. The tabular workpieces 1 are, without limitation, metal sheets, plates, bipolar plates, etc. This naturally applies only by way of example. For this purpose, the tabular workpieces 1 in question are held firmly on a revolving conveyor belt 2 by means of reduced pressure. In addition, magnet holding elements 3 that are merely indicated in FIG. 1 may also be arranged in the interior of a holding device 4. By means of the magnet holding elements 3, the plate-shaped workpieces 1 can additionally be magnetically attracted and held in contact with the conveyor belt 2. For this purpose, according to the exemplary embodiment, a plurality of magnet holding elements 3 arranged in the transport direction T are provided in the interior of the holding device 4 in question.Consequently, the holding device 4 is formed as a hollow chamber or comprises such a hollow chamber in the interior. According to the exemplary embodiment, the holding device 4 itself is designed as a hollow chamber. As a result, the hollow chamber can communicate with a plurality of vacuum lines 9 which can be seen in FIG. 1 and which are in turn equipped with an associated blower or vacuum blower 10 for generating vacuum in the interior of the holding device 4. That is, with the aid of the fans 10, a negative pressure is applied to the interior of the holding device 4 via the negative pressure lines 9.The conveyor belt 2 is guided past the relevant holding device 4 in the transport direction T. For this purpose, gear wheels 5 are provided on each end of the holding device 4, via which the drive of the conveyor belt 2 takes place.This is because, within the scope of the exemplary embodiment and not restrictively, the conveyor belt 2 is a toothed belt conveyor belt 2. the conveyor belt 2 has teeth or rows of teeth 6 on both sides on its underside, corresponding to the sectional illustration in FIG. 3. The teeth or rows of teeth 6 engage in the correspondingly configured gearwheels 5 for driving the conveyor belt 2. In addition, the conveyor belt 2 shown in section in FIG. 3 is additionally provided with antistatic properties. For this purpose, an antistatic coating 7 indicated in FIG. 3 may be provided on its lower surface, which is also basically unnecessary. Opposite the coating 7, a further coating can be provided on the surface of the conveyor belt 2 facing the workpieces 1, which coating is one which closes off any pores on the surface of the conveyor belt 2, for example as paint or the like. As a result, the conveyor belt 2 can be cleaned particularly easily on its surface facing the workpieces 1.According to the exemplary embodiment, at least one tension carrier 8 is embedded in the conveying belt 2 or its belt body 13, which runs in the longitudinal direction or the transport direction T. In fact, several tension members 8 are provided in the form of threads of, for example, polyamide. The design is additionally made such that the tension members 8 are formed as components and in particular warp threads 8 of a polyamide fabric embedded in the belt body 13.The fabric embedded in the belt body 13 with the warp threads 8 made of polyamide ensures, within the scope of the exemplary embodiment, that the conveying belt 2 is designed overall to be antistatic. As a result, in the case of the revolving drive of the conveyor belt 2 along the holding device 4, possible static loads on the conveyor belt 2 are avoided, taking into account the respective end gearwheels 5. The conveyor belt 2 or its belt body 13 is made of plastic according to the exemplary embodiment, and can be produced in particular by an extrusion process. At this point, PVC (polyvinyl chloride) or even polyurethanes (PU) have proven particularly advantageous as plastics. This is of course not restrictive.As already explained, the vacuum lines 9 open out from the respective blower 10 into the hollow chamber or the holding device 4 designed as a hollow chamber. In fact, the holding device 4 is equipped on the head side for this purpose with a vacuum channel 11 which is merely indicated in FIG. 1 and which can additionally be seen in the top view according to FIG. 2 on the conveyor belt 2. The vacuum channel 11 extends in the longitudinal direction of the conveyor belt 2 and also in the transport direction T.The conveyor belt 2 is now guided with the workpieces 1 to be placed against it past the holding device 4 in the transport direction T. The workpieces 1 are held in the vacuum channel 11 by generating vacuum. This is done in detail in that suction openings 12 are guided past the vacuum channel 11 in the conveyor belt 2 and consequently the suction openings 12 are subjected to vacuum, namely via the vacuum channel 11.A comparative consideration of FIGS. 2 and 3 reveals that, according to the exemplary embodiment, the respective suction opening 12 is formed as a punching opening 12 which passes through the belt body 13. In fact, the punching opening 12 in the exemplary embodiment is designed as an elongated hole punching opening 12, as the plan view in the illustration according to FIG. 2 can be seen. The slot punching opening 12 in question is oriented transversely to the transport direction T. Furthermore, the elongated hole punching opening 12 has a transverse orientation in comparison with the vacuum channel 11. The belt body 13 according to the exemplary embodiment is not only antistatic, namely by the woven fabric of polyamide embedded in the belt body 13. Instead, the belt body 13 is also configured transparent overall.As a result, the vacuum device shown in an overview in FIG. 1 can be equipped with an illumination unit 14, which is indicated by way of example in FIG. 1. The lighting unit 14 is placed in the interior of the holding device 4 or the hollow chamber realized at this location. In fact, the illumination unit 14 is provided at the head side of the holding device 4. In this way, the illumination unit 14 can pass through the conveying belt 2 guided along it according to the exemplary embodiment, because the conveying belt 2 is transparent to the light beams generated in the illumination unit 14 and emitted thereby (predominantly in the visible range).This makes it possible to place an image recording device 15 opposite the illumination unit 14 and with respect to the conveying belt 2 which is on the center in contrast thereto. According to the exemplary embodiment, the image recording device 15 is a camera 15, with the aid of which not only the conveyor belt 2 but also the workpieces 1 transported thereon are optically captured in this way. This is ensured by the light emanating and emitted from the illumination unit 14. In this case, not only is it possible to record the contour of the tabular workpiece 1 in question, but it is also possible, for example, to determine any damage to the surface, oblique positions, soiling, etc. in this way with the aid of the image recording device 15. As a result, following this quality test, it is possible to discharge individual sheet-like workpieces 1 if they have not passed the quality test.The lighting unit 14 is generally an LED light bar 14 which has a predetermined longitudinal and transverse extent. It can be seen that according to the exemplary embodiment, the LED light bar 14 has an area occupancy, so that overall a luminous area is generated by the lighting unit or LED light bar 14. This illuminated area can be optically detected with the aid of the image recording device 15.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedEP 0 893 371 B1

[0002] DE 30 01 531 A1

[0002] WO 2021 / 089315 A1

[0003] DE 20 2021 105 990 U1 [0005, 0006]

Claims

Conveyor belt (2) for the transport of workpieces (1), in particular for the resting transport of tabular workpieces (1) such as metal sheets, plates or foils, having a belt body (13) with suction openings (12) which communicate with a reduced-pressure channel (11) in a holding device (4), wherein the conveyor belt (2) with the workpieces (1) to be placed thereon is guided past the holding device (4) in the transport direction (T) and the workpieces (1) are held on the conveyor belt (2) by generating reduced pressure in the reduced-pressure channel (11) and thus at the suction openings (12) and are moved together with the conveyor belt (2) in the transport direction (T), characterized in that the respective suction opening (12) is designed as a punching opening (12) which reaches through the belt body (13).Conveyor belt (2) according to Claim 1, characterized in that the punching opening (12) is designed as an elongated hole punching opening (12).Conveyor belt (2) according to Claim 2, characterized in that the slot punching opening (12) has a longitudinal extent oriented transversely with respect to the transport direction (T) and the vacuum channel (11).Conveyor belt (2) according to one of Claims 1 to 3, characterized in that the belt body (13) is antistatic and preferably transparent.Conveyor belt (2) according to claim 4, characterised in that the belt body (13) is made of plastic, in particular PVC and / or PU.Conveyor belt (2) according to one of Claims 1 to 5, characterized in that the belt body (13) is formed with tension members (8) running in the longitudinal direction in the form of threads (8) made, for example, of polyamide.Conveyor belt (2) according to claim 6, characterised in that the tension members (8) are formed as components, in particular warp threads (8), of a fabric embedded in the belt body (13) and made of polyamide, for example.Conveyor belt (2) according to one of Claims 1 to 7, characterized in that it is a toothed belt conveyor belt which is guided via gearwheels (5) provided in each case on the end side of the holding device (4).Vacuum device for transporting tabular workpieces (1), in particular for transporting tabular workpieces (1) such as metal sheets, plates or films resting thereon, having a holding device (4), and having a conveying belt (2), the belt body (13) of which is equipped with suction openings (12) which communicate with a vacuum channel (11) in the holding device (4), wherein the conveying belt (2) with the workpieces (1) to be placed thereon is guided past the holding device (4) in the transporting direction (T) and the workpieces (1) are held on the conveying belt (2) by generating vacuum in the vacuum channel (11) and thus at the suction openings (12) and are moved together with the conveying belt (2) in the transporting direction (T), characterized in that the respective suction opening (12) is designed as a punching opening (12) which reaches through the belt body (13).Device according to claim 9, characterised in that the punching opening (12) is formed as an elongated hole punching opening (12).Device according to claim 9 or 10, characterised in that at least one vacuum unit (9, 10) connected to the holding device (4) is provided.Device according to one of Claims 9 to 11, characterized in that the holding device (4) is equipped on the inside with at least one lighting unit (14).Device according to claim 12, characterised in that the illumination unit (14) is provided on the head side of the holding device (4) and irradiates the conveyor belt (2) guided along it.Device according to claim 12 or 13, characterised in that the lighting unit (14) is designed as at least one LED light strip (14) of predetermined longitudinal and / or transverse extent.Device according to claim 14, characterised in that an image recording device (15), in particular a camera (15), is placed opposite the LED light bar (14), which recording device records the conveyor belt (2) irradiated by the light of the LED light bar (14) and / or the workpieces (1) transported thereon.

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