Calibrating a conveyor and metering device

Description

[0001] The invention relates to a conveying and dosing device according to the preamble of claim 1. These conveying and dosing devices include, among others, belt conveyors in the form of belt scales or dosing belt scales designed for the continuous weighing of bulk materials transported on a conveyor belt. These belt scales and dosing belt scales have an endless conveyor belt that is set in motion by a drive and is supported in sections by rollers and idlers. An idler is typically supported by a weighing device in the form of a force transducer, a load cell, or other load sensing assembly to provide a gross weight signal for a known section of the belt length, indicating the weight of the material. The gross weight signal, proportional to the load and generated by the material lying on the conveyor belt, is then further processed in weighing electronics.

[0002] The belt load Q and the speed v are constantly measured and multiplied together. The result is the conveying force, from which the conveying quantity is determined.

[0003] To ensure the proper functioning of the conveying and dosing device, the weighing devices must be tared and / or adjusted at regular intervals.

[0004] This need arises primarily from temperature fluctuations in the vicinity of the conveying and dosing device, as well as from wear and tear and the decreasing strength of the conveyor belt or conveying medium. Adjusting the conveying and dosing device is also common practice when changing the conveyed material.

[0005] When taring a belt scale, the tare weight of the conveyor belt acting on the weighing device is determined during one belt revolution, and the corresponding parameter is stored in the weighing electronics. After taring, the average belt load over one revolution is set to zero, so that when determining the conveying capacity, only the belt load without the weight of the conveyor belt can be calculated.

[0006] During adjustment, however, errors in the conveyor's mechanics, or uncertain mechanical data such as lever ratio or belt inclination, can be detected. For this purpose, the scale is checked using test weights such as commercial weights.

[0007] For this purpose, the test weights are attached to the existing weighing device using, for example, an eyelet, a wire, a rod, or other suspension devices. An adjustment program is then used to determine the ratio between the target weight and the test weight reading. For an ideal scale, this ratio should be 1.0000.

[0008] However, attaching test weights to the weighing device is extremely complex and time-consuming, especially with enclosed conveying and dosing devices, as access to the weighing devices is made more difficult by attachments such as geared motors or switch boxes etc. on the frame.

[0009] US Patent 2007 / 0074560 A1 discloses a holder for a cylindrical test weight in which the test weight is positioned below the conveyor rollers. During normal conveyor operation, the test weight rests on a tray beneath the conveyor rollers and is simultaneously secured at both ends within two loops connected to the load cells to be adjusted. For the adjustment process, the two loops are tightened by means of a dedicated actuator, thus raising the test weight, whose load acts on the load cells, allowing the load cells and the associated controller to be adjusted.

[0010] This solution requires more construction work and is also costly due to the additional actuator needed.

[0011] US Patent 3,976,150 discloses a belt scale in which test weights of the same size as the expected conveyed weight can be applied to enable the signals from the weighing devices to be evaluated accordingly. For this purpose, a stationary frame is arranged on which the test weights are stored and from which they can be lowered onto a second frame. The load from the test weights is transferred by means of the second frame into the support frame of the conveyor belt, which in turn is supported on the load cells.

[0012] From AU 631 695 B2, a belt scale with a specially shaped test weight is known, which can be suspended from a strut connecting two weighing devices. However, access for an operator must be provided below the conveyor belt to attach the test weight.

[0013] Other known solutions involve fixed holders on the conveying and dosing devices, designed to hold the test weights. For example, GB 1 557 207 A discloses a belt scale with a permanently installed lever mechanism for applying test or calibration weights. However, these holders or mechanisms are also permanently installed and typically protrude laterally from or extend beyond the frame. Dirt, contact, or wind loads can therefore alter or disrupt the detection of the weight signal, potentially leading to a malfunction of the conveying system.

[0014] Against this background, the task arises to introduce test forces from test weights into the weighing devices in a simple manner for conveying and dosing devices, in order to be able to carry out the adjustment process as quickly and safely as possible.

[0015] This problem is solved by a device having the features of claim 1 or claim 4. Furthermore, this problem is solved by a method according to claim 6. Advantageous embodiments of the invention are the subject of the dependent claims and are explained in more detail below.

[0016] The invention comprises a conveying and dosing device with an endless conveyor belt, wherein sections of this conveyor belt are mounted on weighing devices for determining the mass of the conveyed material. These weighing devices are connected to an electronic evaluation unit. The weighing devices generate a signal proportional to the load on the conveyor belt and send this signal to the evaluation unit.

[0017] The weighing devices also feature a bearing bracket designed for the positive-locking attachment of a component, a holding device, and / or a test weight. The bearing bracket typically serves only to attach the force transducer to the weighing device or to the frame structure of the conveying and dosing device. Furthermore, it serves to transfer the weight loads from the weighing roller to the force transducer. The solution according to the invention now provides an additional connection geometry on the bearing bracket for the component or test weight. This allows the corresponding component or test weight to be positively locked to the bearing bracket.The conveying and dosing device according to the invention also has a frame or substructure provided with an opening in the area of ​​and / or above the bearing brackets, so that the attachment or the test weight can be placed onto the bearing bracket from the outside, preferably from above, through the opening. According to the invention, the attachment of the component, the placement of the test weight, and the removal of the test weight and the component can be carried out during the conveying operation of the conveying and dosing device.

[0018] The bearing brackets according to the invention have a projecting extension. This projecting extension of the bearing bracket has a recess at its end facing away from the bearing bracket, i.e., at the projecting end.

[0019] Advantageously, the bearing bracket of the weighing device also has a fork bearing for a shaft journal of a weighing roller, on which the conveyor belt of the conveying and dosing device is supported at least in some areas.

[0020] The invention further provides an attachment for a conveying and dosing device, wherein this attachment has a support area for a separate test weight and a connection area with a pin that is designed for a positive-locking connection with the bearing bracket, the extension of the bearing bracket, and / or the recess on the extension of the bearing bracket. This attachment can be stored in the frame or substructure of the conveying and dosing device at a suitable and accessible location. When required for adjustment, it can then be attached to the bearing bracket from the outside through an opening in the frame, preferably from above.

[0021] Advantageously, the pin in the connection area of ​​the attachment has a fork shape, a cylindrical shape or a stepped cylindrical shape.

[0022] The attachment or holder for the test weight(s) thus enables a known weight force or test force to be introduced into the weighing device. For this purpose, the attachment is provided with a connection geometry that corresponds to the geometry of the weighing device, so that a positive-locking connection is established between the weighing device and the attachment or holder.

[0023] The geometry of the two elements, weighing device and attachment, allows for direct force transmission into the weighing device without additional force transmission elements such as springs or levers. Therefore, there is no risk of the weighing results being distorted due to friction or altered leverage.

[0024] The geometry of the bearing bracket and that of the attachment are still coordinated in such a way that the attachment can be placed on the bearing bracket without jamming or tilting.

[0025] The support area of ​​the attachment has a flat support surface suitable for use with test weights in the form of commercial weights, or other components with a pre-determined weight, such as tools or similar items.

[0026] Advantageously, the conveying and dosing device has a holder or receptacle on its frame for the attachment, so that it can be stored securely and with easy access in the area of ​​the weighing device.

[0027] Furthermore, the invention provides a method for adjusting a conveying and dosing device, in which a known test weight is applied to a weighing device of the conveying and dosing device in order to compare a weight signal generated by applying the test weight with a stored signal corresponding to the test weight. For applying the test weight, an attachment is positively locked to the weighing device. For this purpose, a pin of the attachment is inserted into the corresponding connection geometry of the weighing device.

[0028] The method according to the invention also provides that the attachment is inserted from above through an opening in the frame of the conveying and metering device.

[0029] For this, only the pin of the attachment needs to be pushed through the opening in the frame. Due to the connection geometry of the attachment and the weighing device, these elements are then positively connected to each other without the measurement result being distorted by clamping forces or force bypass.

[0030] Furthermore, the procedure provides that the opening in the conveying and dosing device is protected from the ingress of bulk material or dirt by inserting a closure after the test weight and the attachment have been removed.

[0031] The invention is explained in more detail below using an exemplary embodiment. The figures show: Fig. 1 a perspective view of a part of a conveying and dosing device according to the invention in the form of a dosing belt scale with attached attachment and test weight, Fig. 2 a side view of the part of the conveying and dosing device according to the invention made of Fig. 1, Fig. 3 a bottom view of the part of the conveying and metering device according to the invention made of Fig. 1 Fig. 4 shows a side view of a support bracket of the weighing device with an attached component, Fig. 5 shows a bottom view of the support bracket of the weighing device with an attached component. Fig. 4 Fig. 6 a perspective view of part of a conveyor belt resting on carrying rollers and a measuring roller, Fig. 7 a detail from Fig. 6 with the support situation of the measuring roller on a weighing device, Fig. 8 a weighing device in perspective view.

[0032] The figures are schematic and serve solely to illustrate the invention. Identical elements are identified by the same reference symbols.

[0033] Fig. 1, Fig. 2 and Fig. 3Figure 1 shows part of a dosing belt scale with a substructure 1 made of sheet steel on which an endless conveyor belt (not shown) is arranged, which runs around a drive and deflection roller (also not shown).

[0034] The conveyor belt, on which bulk material rests during operation, is typically moved between two material guide rails 13. A weighing device 2 is attached to a frame bracket 11, which is stiffened by plates 12 and cross braces 14. According to the invention, an attachment 3 is attached to the weighing device 2 and is positively connected to it. The attachment 3 has a flat support surface 31 on which a test weight 4 can be loosely placed.

[0035] The weighing device 2, also called the compact weighing component, is attached to the frame bracket 11 by means of a mounting plate 24. A force transducer 21 is bonded to the mounting plate 24. A bearing bracket 22 positively encloses the force transducer 21, so that it is fork-mounted there.

[0036] Fig. 6 Figure 1 shows a section of a conveyor belt 5, which forms the so-called weighing bridge. In this section, the endless conveyor belt 5 rests on two support rollers 6 and on a measuring roller 7. As shown in Figure 1, the continuous conveyor belt 5 rests on two carrying rollers 6 and on a measuring roller 7. Fig. 7As can be seen, the measuring roller 7 rests with its two axle journals 71 in the designated recesses 221 of the bearing bracket 22 of the weighing device 2. Thus, during operation of the conveying and dosing device, the section of the conveyor belt 5 that rests on the measuring roller 7, along with the conveyed material, is detected and weighed by the weighing devices 2. The recess 221 on the bearing bracket 22 forms the point of load application for the measuring load.

[0037] According to the invention, the bearing bracket 22 is, as shown in Fig. 5 and 8 As can be seen, it is additionally provided with a projecting extension 222, which enables the attachment of the component 3 to the weighing device 2. Advantageously, this can be produced cost-effectively when cutting out the sheet metal components of the bearing bracket 22, for example in a laser cutting system.

[0038] The fork geometry of the pin 32 of the attachment 3 is particularly advantageous, as it ensures that the attachment 3 is held securely on the bearing console 22 or the extension 222 of the bearing console.

[0039] Existing conveying and dosing devices can also be retrofitted with weighing devices 2 according to the invention. For this purpose, openings 111 for the insertion of the attachments 3 or test weights 4 only need to be subsequently created in the frame or substructure 1 of the conveying and dosing device. The associated effort is, however, more than justified by the time saved during subsequent adjustment procedures. Reference symbol list

[0040] 1 Substructure 11 Frame bracket 12 Stiffening plate 13 Material guide rail 14 Cross brace 2 Weighing device, compact weighing unit 21 Force transducer, weighing beam 22 Bearing bracket 221 Recess 222 Extension 23 Overload protection 24 Mounting plate 3 Attachment 31 Support surface 32 Fork geometry 4 Test weight 5 Conveyor belt 6 Carrying roller 7 Measuring roller 71 Axle journal of the measuring roller

Claims

1. Conveying and metering device comprising - an endless conveyor belt (5) or conveyor belt, wherein partial regions of this conveyor belt (5) or conveyor belt are placed on weighing devices (2) for determining the mass of the conveyed material, which are connected to an electronic evaluation device, characterized in that each weighing device (2) - comprises a force transducer (21) and a bearing console (22), - wherein the bearing console (22) - - comprises a recess (221), which forms a measuring load introduction point for the load introduction of the weight loads from a measuring roller (7) into the force transducer (21), and - - comprises a projecting extension (222), which is provided for the positive-fit reception, positive-fit fastening, and positive-fit removal of an attachment part (3) or a test weight from outside, preferably from above, through an opening in the frame or the substructure of the conveying and metering device during conveying operation, such that a test force is introduced into the weighing device (2).

2. Conveying and metering device according to claim 1, characterized in that the projecting extension (222) of the bearing console (22) comprises a recess at its projecting end.

3. Conveying and metering device according to one of the preceding claims, characterized in that the bearing console (22) of the weighing device (2) additionally comprises a fork bearing (221) for a shaft journal (71) of a measuring roller (7), on which the conveyor belt (5) of the conveying and metering device is placed at least in partial regions.

4. Attachment part (3) for a conveying and metering device according to one of the preceding claims, characterized in that it comprises a bearing region (31) for a test weight (4) and a connection region (32) with a pin, which is provided for the positive-fit connection with the bearing console (22), the extension (222) of the bearing console (22), or the recess at the extension (222) of the bearing console (22).

5. Attachment part (3) for a conveying and metering device according to claim 4, characterized in that the pin in the connection region (32) comprises a fork shape, a cylinder shape, or a stepped cylinder shape.

6. Method for adjustment of a conveying and metering device according to one of claims 1 to 3, - wherein a test weight (4) is applied to a weighing device (2) of the conveying and metering device in order to compare a weight signal, which is generated by application of the test weight (4), with a stored signal corresponding to the test weight, characterized in that an attachment part (3) or the test weight (4) is positively fastened to the bearing console (22) of the weighing device (2), by inserting a pin of the attachment part (3) or of the test weight (4) during conveying operation from outside, preferably from above, through an opening in the frame of the conveying and metering device into the corresponding connection geometry of the bearing console (22), such that the test force is introduced into the weighing device (2).

7. Method according to claim 6, characterized in that the test weight (4) can comprise any geometry and is placed on a bearing surface (31) of the attachment part (3).

8. Method according to one of claims 6 or 7, characterized in that the opening (111) of the frame is protected against penetration of bulk material or dirt after removal of the test weight (4) and the attachment part (3) by inserting a closure.