GB2581005A

GB2581005A - Checkweigher and method for verifying a dynamic weight

Info

Publication number: GB2581005A
Application number: GB1917322.8A
Authority: GB
Inventors: Maher Colin
Original assignee: Minebea Intec Aachen GmbH and Co KG
Current assignee: Minebea Intec Aachen GmbH and Co KG
Priority date: 2018-12-14
Filing date: 2019-11-28
Publication date: 2020-08-05
Anticipated expiration: 2039-11-28
Also published as: GB2581005B; GB201917322D0; DE102018132284A1

Abstract

A checkweigher 1 for continuous weighing of moving products 3comprises at least one transport device 4 with a load cell connected to transport device 4 in weighing region 5. The checkweigher is in wireless or wired communication with a static balance 2 via interface 7. The static balance 2 may verify at least one dynamically determined weight value of the checkweigher 1, verification may be during running operation of checkweigher 1 and checkweigher 1 may discharge weighed product 3 via conveyer 6 and supply this to static balance 2. Also provided is a method for verifying a dynamically determined weight of a product by determining the product weight with a checkweigher and verifying the determined weight with a static balance 2. The statically determined weight may be forwarded via a wired or wireless communication to checkweigher 1 via interface 7. The checkweigher may calculate a deviation between dynamically and statically determined weights for a dynamic correction value, said correction value may be altered by statically weighing a second product.

Description

Intellectual Property Office Application No. GB1917322.8 RTM Date:27 May 2020 The following terms are registered trade marks and should be read as such wherever they occur in this document: p. 6 1. 16: Wi-Fi, Bluetooth p. 8 1. 3 and 1. 5: QR Code Intellectual Property Office is an operating name of the Patent Office www.gov.uk /ipo Checkweigher and method for verifying a dynamic weight FIELD OF THE INVENTION The invention relates to a checkweigher and a method for verifying at least one dynamic weight of at least one product.

TECHNICAL BACKGROUND

From the prior art, a variety of checkweighers are known. These weighing devices have a transport device, which is often a one-piece or multi-part conveyor belt. The products are conveyed by a conveyor over the weighing range of the checkweigher and transported to a discharge conveyor. On the weighing area of the checkweigher, the products are weighed, whereby the products are transported over the weighing range at a defined transport speed. Thus, the weighing of the products is not done at standstill, as in a static balance, but while the products move beyond the weighing range of the checkweigher. The weighing of a product with a checkweigher is therefore also known as dynamic weighing.

A problem in the case of dynamic weighing is that a weight value determined dynamically with the checkweigher deviates from the static weight value determined by a static balance, which was determined by the same product. This deviation between the dynamically determined weight value and the statically determined weight value results inter alia from the air resistance of the moving product, which may result in slight lift of the product, which makes the product "lighter". Another reason for the deviation is that the conveyor belt in the portion in which the product is weighed may yield slightly by the weight of the product, causing acceleration of the product in the direction of gravity. Furthermore, unevenness in the conveyor belt can lead to an acceleration of the product in the direction of gravity.

Consequently, a dynamically determined weight value always deviates by a specific value from a statically determined weight value.

In order to compensate a deviation between a dynamically determined weight value to a statically determined weight value, DE 32 06 061 C1 discloses, for example, that a test product is first statically weighed and then dynamically weighed several times. From the dynamically determined weight values, an average value is then formed. This average value is then deducted from the statically weight value determined with the same test specimen, resulting in a correction value. If products are weighed dynamically on the checkweigher during normal operation, the previously determined correction value is automatically added to the respective measured value by a controller, thereby determining the actual weight of the product is relatively accurately.

Furthermore, DE 10 2016 117 966 Al discloses a method in which a checkweigher has a control device which is configured that the conveyor of the checkweigher automatically stops during its operation in a direction from a start position to a target position and then can be operates automatically in one direction from the target position to the start position. Thus, the controller may automatically stop the moving conveyor and then automatically reverse the direction of movement. This makes it possible for a product placed on the conveyor to be initially conveyed from the start position toward the target position, weighed in a region between the start position and the target position and automatically returned to the start position after weighing by reversing the direction of movement. In this way, a product can automatically be weighed multiple times without the need for an operator to pick up the product from the conveyor multiple times and place it back on the starting position.

A disadvantage of the known prior art is that for a correction of the dynamically determined weight value, the checkweigher must be stopped and thus a production plant, in which the checkweigher is integrated, stands still in this period.

DESCRIPTION

It is an object of the invention that a correction of a dynamically determined weight value is possible during operation of the checkweigher.

This object is achieved by a checkweigher for the continuous weighing of moving products, whereby the checkweigher comprises at least one transport device and a load cell, whereby the load cell is connected to the transport device via a force introduction region, whereby the checkweigher have a communication interface, whereby the checkweigher is connected via the communication interface wirelessly and/or wired to a communication interface of a static balance.

The static balance verifies at least one dynamically determined weight value of the checkweigher. The checkweigher does not have to be stopped because of the verification by the static scale, and the dynamically determined weight value can be verified during operation or production of a production plant, whereby the checkweigher is integrated into the production plant and is therefore an essential component of the production plant.

In another embodiment, the checkweigher automatically discharges at least one dynamically weighed product and supplies it to the static balance. In this case, the checkweigher can eject the product from the current production, for example with a pusher or a switch, and transport it into a collecting container or direct it to a separate conveyor belt. An operator of the production plant can then take the product and weigh it on the static balance. Alternatively, the product can also be automatically supplied to the static balance via the separate conveyor belt.

As described above, the verification of at least one dynamically determined weight of at least one product is carried out by the checkweigher, determining at least one dynamically determined weight. For this purpose, the checkweigher has at least one controller, a transport device and a weighing range, whereby the product is transported by the transport device over the weighing range of the checkweigher and the dynamically determined weight value is verified during running operation of the checkweigher with the static balance.

The statically determined weight value can be forwarded from the static balance via the wired and/or wireless communication interface to the controller of the checkweigher. The controller then compares the dynamically determined weight value with the statically determined weight value of the product and can thereby calculate a deviation from the dynamically determined weight value to the statically determined weight value.

If the deviation between the statically determined weight value and the dynamically determined weight value is greater than a previously defined tolerance, in particular greater than or equal to 5%, preferably greater than or equal to 10%, particularly preferably greater than or equal to 20%, then the controller of the checkweigher may output a message on a display device of the production plant and/or on a display device of the checkweigher that the deviation between the statically determined weight value and the dynamically determined weight value lies outside a defined tolerance and that a dynamic correction value for dynamic weighing should be adjusted. If the deviation between the statically determined weight value and the dynamically determined weight value is within a defined tolerance, the checkweigher controller may display a message on the display device indicating that the deviation is within the tolerance and that there is no need to adjust the dynamic correction value.

In a further embodiment, the controller of the checkweigher requests the operator of the production plant that the static balance must determine at least a second statically determined weight value of a second product in order to change the dynamic correction value. Thereby, the deviation between the static weighing and the dynamic weighing can be averaged, whereby the average value of the deviation of the at least two products is used as a reference for the dynamic correction value. Preferably up to ten products are ejected from the running production of a production plant within a period of time in order to verify them with the static scale. Thus the ten statically determined weight values are averaged and serve as a reference for the dynamic correction value.

In a further embodiment, at least two product types are stored in the controller of the checkweigher, whereby a change of the dynamic correction value is assigned to the respective product type and stored in the controller. This allows a simple changeover of the production plant or the checkweigher to another product without losing the changed dynamic correction values. Thus, when changing over the production plant to another product, the controller of the checkweigher only has to be informed that a changeover to another product takes place. This can be done for example by a manual input or by a sensor which monitors at least one product feature. For example, the sensor may be an optical sensor, which scans a barcode and/or monitors a geometric dimension of a product.

In a further embodiment, the controller requests the operator of the production line to verify at least one dynamically determined weight value. This verification can take place at regular or irregular intervals, whereby the dynamically determined weight value is verified by the static scale after it has been weighed with the checkweigher.

BRIEF DESCRIPTION OF THE FIGURES

Further advantageous aspects will become apparent from the following description of preferred embodiments with reference to the drawings, whereby: Fig. 1 is a simplified representation of a checkweigher and a static balance, Fig. 2 is a flowchart of a method for verifying a dynamic weight value. DETAILED DESCRIPTION OF THE EMBODIMENTS Fig. 1 shows a simplified representation of a checkweigher 1 and a static balance 2. In the case of the static balance 2, a weighing of a product 3 takes place in a stationary or non-moving state, whereas in the case of the checkweigher 1, a weighing of a product 3 takes place in a moved state. In the case of the checkweigher 1, the product 3 is guided by a feed conveyor 4 onto a weighing area 5 of the checkweigher and subsequently transported to a discharge conveyor 6.

The checkweigher 1 and the static balance 2 each have a communication interface 7. The communication interface 7 can be both a wireless and a wired communication interface 7. Whereby a wireless communication interface 7 is preferably a radio connection, in particular a Wi-Fi or Bluetooth connection. FIG. 1 shows a wired communication interface 7.

Furthermore, a pusher or a switch can be arranged on the checkweigher 1, which can eject the product 3 from a product flow to verify a dynamically determined weight value, whether this is within a defined tolerance or outside a defined tolerance. For this purpose, the checkweigher 1 is connected to the static balance 2 via the communication interface 7. The discharged product 3 is automatically or manually placed on a weighing range 9 of the static balance 2 and then statically weighed. Via the communication interface 7, the statically determined weight value of the product 3 is transmitted to a controller of the checkweigher 1, so that the controller of the checkweigher 1 can compare the statically determined weight value with the dynamically determined weight value. Is a deviation of the dynamically determined weight value from the statically determined weight value detected by the controller, which is greater than a defined tolerance, the controller outputs a message on a display device 8. Then a dynamic correction value of the checkweigher 1 must be adjusted.

Fig. 2 shows a flowchart of a method for verifying a dynamically determined weight value during running operation of the checkweigher 1. In step S100, the product 3 is weighed by the checkweigher 1 and the controller of the checkweigher 1 provides a dynamically determined weight value of the product 3.

In step S200, the verification of the dynamically determined weight value is started. For this purpose, for example, an operator selects a corresponding option in the controller of the checkweigher 1, which starts the verification of the dynamically determined weight value. Alternatively, the controller of the checkweigher can automatically start a verification of the dynamically determined weight value at regular intervals. In particular, the interval between two verifications of the dynamically determined weight value is at least one minute, preferably one to ten minutes, especially two to five minutes.

In step S300, at least one product 3 is ejected after the dynamically determined weight value has been determined, in particular by a pusher and/or a switch mechanism. Up to ten products 3 are preferably ejected to verify the dynamically determined weight values. The number of products 3 to be ejected can be preset and/or set in the controller of checkweigher 1 and/or an operator can select the number of products 3 to be ejected by pressing a button.

In step S400, the at least one product 3 to be ejected can be assigned to a product type which is stored in the controller and the dynamically determined weight is stored. If more than one product is ejected, the dynamically determined weight values are stored in the controller one after the other so that the dynamically determined weight values can be assigned to the corresponding product 3. In addition, a product characteristic can be stored in the controller which clearly assigns the respective product 3 to a dynamically determined weight value. For example, such information can be stored on a barcode and/or a OR code that is attached to the product. For this purpose, the checkweigher 1 can, for example, have a label printer that attaches a label with, for example, a barcode and/or a OR code to product 3 before the product 3 is ejected. Before or after the product 3 is or has been weighed on the static scale 2, the product characteristic can, for example, be read in with a scanner, whereby the product 3 can be clearly assigned to a dynamically determined weight value. This prevents confusion between the ejected products 3.

In step S500, the dynamically weighed product 3 is weighed on the static balance 2 and a static weight value is determined. This statically determined weight value can then be transmitted to the controller of the checkweigher 1 via the communication interface 7 or entered manually on the checkweigher 1.

In step S600, the controller of the checkweigher 1 compares the dynamically determined weight value with the statically determined weight value. If a deviation of the dynamically determined weight value from the statically determined weight value is determined, which is greater than a defined tolerance, in particular greater than or equal to 5%, preferably greater than or equal to 10%, particularly preferably greater than or equal to 20%, the controller outputs a message, for example on the display device 8, that the dynamically determined weight value is outside a defined tolerance and asks an operator to adjust the dynamic correction value.

The dynamic correction value is changed in step S700. To store the change of the dynamic correction value, at least one further product 3 is ejected to verify the repeatability of the change of the dynamic correction value. If the second product 3 has a statically determined weight value which lies within a defined tolerance, the new dynamic correction value is accepted and stored in the controller. Otherwise, the verification of the dynamically determined weight value starts again.

To confirm the dynamic correction value the controller specifies a predetermined time window, for example within two to ten minutes. If no weighing of a second product 3 take place by the static balance and is transmitted not the statically determined weight value via the communication interface 7 to the controller of the checkweigher 1 or manually entered at the checkweigher 1, the dynamic correction value is automatically reset to the previous correction value or the new dynamic correction value is not stored and the previous correction value is further used to correct the dynamically determined weight value. As a result, a faulty weighing or incorrect operation should be excluded.

The change in the dynamic correction value takes place in a running batch of the checkweigher 1. The new dynamic correction value is from this point in time to all future weighing valid, without having to be stopped the checkweigher 1.

Furthermore, the changes of the dynamic correction value can be stored in the controller of the checkweigher 1. For this purpose, there may be a manipulation-proof memory in the controller of the checkweigher 1 for the traceability of the change in the dynamic correction value, whereby this memory cannot be overwritten. For example, the respective dynamically determined weight value and/or the corresponding statically determined weight value and/or the deviation of the dynamically determined weight value from the statically determined weight value can be stored in the controller. Furthermore, a unique ID of an operator can be stored each time the dynamic correction value is changed. This can be done, for example, by an operator logging on to the checkweigher with a user name and password and/or a chip card and/or a fingerprint. This also ensures that only authorized persons have access to the function for verifying the dynamically determined weight value and changing the dynamic correction value.

Referece signs list 1 Checkweigher 2 Static balance 3 Product 4 Feed conveyor Weighing range 6 Discharge conveyor 7 Communication interface 8 Display device 9 Weighing range static balance

Claims

Claims 1. Checkweigher (1) for the continuous weighing of moving products (3), whereby the checkweigher (1) comprises at least one transport device and a load cell, whereby the load cell is connected to the transport device via a force introduction region, whereby the checkweigher (1) have a communication interface (7), characterized in that the checkweigher (1) is connected via the communication interface (7) wirelessly and/or wired to a communication interface (7) of a static balance (2).
2. Checkweigher (1) according to claim 1, characterized in that, the static balance (2) verifies at least one dynamically determined weight value of the checkweigher (1).
3. Checkweigher (1) according to claim 2, characterized in that, the dynamically determined weight value is verified during running operation of the checkweigher (1).
4. Checkweigher (1) according to any one of the preceding claims characterized in that, the checkweigher (1) independently discharges at least one weighed product (3) and supplied this to the static balance (2).
5. Method for verifying at least one dynamically determined weight value of at least one product (3), whereby the weight value of the product (3) is determined by a checkweigher (1), whereby the checkweigher (1) has at least one controller, a transport device and a weighing range (5), whereby the product (3) is transported by the transport device over the weighing range (5) of the checkweigher (1) and the dynamically determined weight value is verified during running operation of the checkweigher (1) with a static balance (2), whereby the static balance (2) determines a statically determined weight value of the product (3).
6. Method according to claim 5, characterized in that, the statically determined weight value of the static balance (2) is forwarded via a wired and/or wireless communication interface (7) to the controller of the checkweigher (1).
7. Method according to claim 5 or 6, characterized in that, the controller of the checkweigher (1) calculates a deviation from the dynamically determined weight value to the statically determined weight value.
8. Method according to any one of claims 5 to 7, characterized in that, in the case of a deviation of the dynamically determined weight value from the statically determined weight value, a dynamic correction value is changed.
9. Method according to claim 8, characterized in that, the dynamic correction value is changed if the dynamically determined weight value deviates from the statically determined weight value by greater than or equal to 5 %.
10. Method according to claim 8 or 9, characterized in that, at least one second statically determined weight value of a second product (3) is determined with the static balance (2) in order to change the dynamic correction value.
11. Method according to any one of claims 8 to 10, characterized in that, at least two different product types are stored in the controller, whereby a change in the dynamic correction value is assigned to the respective product type and is stored in the controller.
12. Method according to any one of claims 8 to 11, characterized in that, a change in the dynamic correction value is stored traceably in the controller, the respective dynamically determined weight value and/or the respective statically determined weight value and/or the deviation of the dynamically determined weight value from the statically determined weight value being stored.
13. Method according to any one of claims 5 to 12, characterized in that, the controller requests an operator to perform a verification of at least one dynamically determined weight value.
14. Method according to any one of claims 5 to 13, characterized in that, the dynamically determined weight value of at least one product (3) is verified at regular and/or irregular intervals, whereby the dynamically determined weight value is verified by the static balance (2) after it has been weighed with the checkweigher (1).