Device and method for weighing a product in a weighing section that includes a conveying device for transporting the product in a direction from a start position over the weighing section to a destination position and a control device configured to automatically stop the conveying device during its operation to achieve a stopped state and then to automatically operate the conveying device in a reverse movement direction until the product is no longer located in the weighing section

Abstract

The present invention relates to a weighing device (1), in particular price labelling device or checkweigher, having a scale for weighing a product in a weighing section (A.sub.W), having a conveying device (4) for transporting the product (3) along a conveying region (F) from a start position (P.sub.start) over the weighing section (A.sub.W) to a destination position (P.sub.destination). To simplify a calibration to compensate for a static-dynamic offset, the invention proposes that the weighing device (1) further has a control device (5) which is configured such that the conveying device (4) can be automatically stopped during its operation in a direction from the start position (P.sub.start) to the destination position (P.sub.destination) and then can be automatically operated in a direction from the destination position (P.sub.destination) to the start position (P.sub.start). Furthermore, the invention relates to a corresponding method for weighing a product (3).

Claims

1. A weighing device comprising: a scale for weighing a product in a weighing section; a conveying device for transporting the product along a conveying region from a start position over the weighing section to a destination position; and a control device configured to automatically stop the conveying device during its operation in a direction from the start position to the destination position to achieve a stopped state, and then to automatically operate the conveying device in a reverse movement direction from the destination position to the start position until the product is no longer located in the weighing section.

2. The weighing device according to claim 1, wherein the control device is configured such that in a first work step sequence, a weighing process is automatically performed by means of the scale during operation of the conveying device in the direction from the start position to the destination position.

3. The weighing device according to claim 2, wherein the control device is configured such that in a second work step sequence which follows or precedes the first work step sequence, a weighing process is performed automatically by means of the scale in the stopped state of the conveying device after stopping the operation of the conveying device in the direction from the start position to the destination position, and wherein the conveying device is then automatically operated in the reverse movement direction from the destination position to the start position.

4. The weighing device according to claim 3, wherein the control device is configured such that the first work step sequence and/or the second work step sequence is run through automatically a plurality of times.

5. The weighing device according to claim 1, wherein the weighing device further comprises at least one movable guide element which is movable between a projecting position in which the guide element adjoins the conveyor region at least in sections or at least protrudes into the conveyor region in sections, and a lying-back position in which the guide element is spaced from the conveyor region.

6. The weighing device according to claim 5, wherein the guide element is arranged such that the product is passed by the guide element along the conveying region.

7. The weighing device according to claim 5, wherein the control device is configured such that the guide element is arranged in the projecting position during operation of the conveying device in the direction from the start position to the destination position and/or in the lying-back position during operation of the conveying device in the reverse movement direction from the destination position to the start position.

8. The weighing device according to claim 1, wherein the conveying device is a belt conveyor or a roller conveyor.

9. The weighing device according to claim 1, wherein the weighing device further comprises a label applying device, which includes a printer, and wherein the conveying region passes by the label applying device from the start position to the destination position.

10. A method for weighing a product using a weighing device according to claim 1, the method comprising the following steps performed successively in the stated order a) placing the product on the conveying device in the start position; b) operating the conveying device so that the product is conveyed in the direction from the start position to the destination position along the conveying region; c) weighing the product when the product is located in the weighing section over the scale, wherein the weighing section lies on the conveying region between the start position and the destination position; d) operating the conveying device so that the product is conveyed in the reverse movement direction from the destination position to the start position; and e) stopping the conveying device when the product is no longer located in the weighing section.

11. The method according to claim 10, wherein the conveying device is stopped for weighing the product automatically.

12. The method according to claim 10, wherein the conveying device is further operated during the weighing of the product.

13. The method according to claim 10, wherein steps b) to e) are run through in succession a plurality of times automatically.

14. The method according to claim 13, wherein a respective mean value is formed from stopped state measured values obtained in step c), which stopped state measured values were obtained during weighing of the product in a stopped state of the conveying device, and operation measured values obtained in step c), which operation measured values were obtained during weighing of the product during operation of the conveying device.

15. The method according to claim 14, wherein the mean value of the stopped state measured values which were obtained during weighing of the product in the stopped state of the conveying device is compared with the mean value of the operation measured values which were obtained during weighing of the product during operation of the conveying device.

16. The method according to claim 10, wherein in step b), a movable guide element adjoins the conveying region in a projecting position or at least protrudes in sections into the conveying region such that as the product passes by the guide element on the conveying device the product comes into contact with the guide element and/or is aligned by the guide element.

17. The method according to claim 16, wherein in step d), the movable guide element lies outside of the conveyor region in a lying-back position such that as the product passes by the guide element on the conveying device the product does not come into contact with the guide element.

18. The method according to claim 17, wherein the movable guide element in or before step b), is automatically moved in the projecting position and/or in or before step d), is automatically moved in the lying-back position.

Description

(1) There is now a plurality of possibilities for designing and further developing the weighing device according to the invention and the method according to the invention for weighing a product. In this regard, reference is made, on the one hand, to the claims subordinate to the independent claims 1 and 10, and, on the other hand, to the description of an embodiment in conjunction with the drawing. The drawing shows:

(2) FIG. 1 a schematic view of a weighing device immediately after the start of a first or second work step sequence,

(3) FIG. 2 the weighing device of FIG. 1 in the further course of the performance of the first work step sequence and

(4) FIG. 3 the weighing device of FIG. 1 in the further course of the performance of the second work step sequence.

(5) In FIG. 1, a weighing device 1 in the form of a price labelling device or a checkweigher is shown schematically in a plan view. The weighing device 1 has a scale 2 for weighing a product 3 in a weighing section A.sub.W and a conveying device 4 for transporting the product 3 along a conveying region F from a start position P.sub.start over the weighing section A.sub.W to a destination position P.sub.destination.

(6) In the present case, the conveying device 4 is a multi-part belt conveyor, wherein the scale 2 is integrated into a middle section of the multi-part belt conveyor.

(7) The weighing device 1 further has a control device 5 which controls, among other things, the conveying device 4, in particular the speed and running direction of the conveying device 4. The control occurs time-dependent and/or path-dependent and/or taking into account position data of the respective moving product. The position data can be determined, for example, by an optical system (not shown) connected to the control device 5, for example, with a camera or light barrier.

(8) In addition, the weighing device 1 has two movable guide elements 6 and 6′, which are arranged along a section of the conveying region F which lies between the start position P.sub.start and the weighing section A.sub.W. The guide elements 6 and 6′ can each, in particular independently or simultaneously, be moved between a projecting position P.sub.V and a lying-back position P.sub.Z. The projecting position P.sub.V is shown in FIG. 1 and the lying-back position P.sub.Z in FIGS. 2 and 3. As can be clearly seen when FIG. 1 is compared with FIGS. 2 and 3, the guide elements 6 and 6′ protrude at least in sections into the conveying region F in the projecting position P.sub.V, whereas the two guide elements 6 and 6′ lie outside the conveying region F in the lying-back position P.sub.Z.

(9) Finally, the weighing device 1 also has a label applying device 7 with a printer 8, which is arranged so that a product 3 can be passed by the label applying device 7 on the conveyor region F from the start position P.sub.start to the destination position P.sub.destination and/or can be provided with a label. In this way, after calibration of the weighing device 1 according to the invention is performed, which is described below, a price labelling process can be performed, in which a plurality of products 3 are weighed by the scale 2 successively in motion and the respective measurement result is taken into account when printing the label associated with the product 3.

(10) The calibration process for the compensation of the static-dynamic offset is now described in more detail below.

(11) Thus, the control device 5 is configured such that the conveying device 4, in the present case thus the belt conveyor or the at least one transport belt, can be automatically stopped during operation in a direction from the start position P.sub.start to the destination position P.sub.destination and then automatically operated in a direction from the destination position P.sub.destination to the start position P.sub.start, thus in the reverse direction. The control device 5 makes it possible in this case to automatically perform a dynamic weighing process by means of the scale 2 in a first work step sequence during the operation of the conveying device in the direction from the start position P.sub.start to the destination position P.sub.destination.

(12) In addition, the control device 5 allows a static weighing process to be performed by means of the scale 2 in another work step sequence, when the conveying device 4 is stopped.

(13) In this case, both the first work step sequence and the second work step sequence can be run through automatically a plurality of times to obtain a plurality of measurement results, from which a mean value is then formed in each case.

(14) FIG. 1 shows how, at the beginning of one of the two work step sequences, the product 3 is conveyed from the start position P.sub.start in the direction of the weighing section A.sub.W and the destination position P.sub.destination. The product 3 in the illustrated state is still located in a first section of the conveying device 4, wherein said guide elements 6 and 6′ are arranged laterally along this section. The guide elements 6 and 6′ are located here in the position P.sub.V projecting into the belt centre, in which the guide elements 6 and 6′ touch the product 3 and can thereby align.

(15) The product 3 is conveyed further from the position shown in FIG. 1 to the weighing section A.sub.W and weighed there either dynamically (at the end of the first work step sequence, see FIG. 2) or statically (at the end of the second work step sequence, see FIG. 3).

(16) In the case of a dynamic weighing process, the product 3 is conveyed over the scale 2 and weighed in the time period in which the product is located vertically over the scale 2. In this case, the product 3 is then, as shown in FIG. 2, transported back again in a direction from the destination position P.sub.destination to the start position P.sub.start by reversing the direction of rotation of the conveying device 4 until it has left the weighing section A.sub.W and in particular has arrived again in the start position P.sub.start. This dynamic weighing process can be repeated several times, wherein the product 3 is weighed, in particular, at the same speed and/or orientation as in the respective preceding weighing process.

(17) In FIG. 3, finally, a part of the second work step sequence is shown, namely the static weighing process. In the second work step sequence, the product 3 is placed by the conveying device 4 exactly vertically over the scale 2 and the conveying device 4 is stopped in this position. The product 3 is then weighed at standstill. Subsequently, the product 3, as shown in FIG. 3, is also transported back by reversing the direction of rotation of the conveying device 4 until it has left the weighing section A.sub.W and in particular has again arrived in the start position P.sub.start. This static weighing process can also be repeated a plurality of times, wherein the product 3 is fed to the weighing section A.sub.W, in particular at the same speed and/or orientation as in the respective preceding weighing process. If necessary, however, even a single static weighing process can suffice for the purpose of calibration. In principle, it is also conceivable in the proposed weighing device 1 or the proposed method to manually enter/store the static weight value after the (static) weight has been determined by means of a checkweigher.

(18) When the product 3 is moved back in the direction from the destination position P.sub.destination to the start position P.sub.start, the two movable guide elements 6 and 6′ are moved into the lying-back position P.sub.Z shown in FIGS. 2 and 3, so that the product 3, when passing the guide elements 6 and 6′, can not come into contact with them. Before the first or second work step sequence is run through again, the guide elements 6 and 6′ are moved again into the projecting position P.sub.V according to FIG. 1. This is done automatically by the control device 5.

(19) Finally, the invention will be explained in more detail with reference to the following exemplary method sequence, in which the following step is first performed, in particular by an operator or automatically by the control device 5 using a feed device (not shown): a) placing a product 3 on a conveying device 4 in a start position P.sub.start,

(20) Thereafter, the control device 5 allows the weighing device 1 to perform the following steps in the order indicated: b) operating the conveying device 4 such that the product 3 is conveyed in the direction from the start position P.sub.start to a destination position P.sub.destination along a conveyor region F and past two projecting guide elements 6 and 6′ which align the product 3, c) weighing the product 3 when the product 3 is located in a weighing section A.sub.W over a scale 2, wherein the weighing section A.sub.W lies on the conveying region F between the start position P.sub.start and the destination position P.sub.destination, wherein according to a first work step sequence, the conveying device 4 continues running during weighing of the product 3 and is stopped only after weighing or wherein according to an alternative work step sequence, the conveying device 4 is already stopped for weighing the product 3, d) operating (that is, restarting again) the conveying device 4, so that the product 3 is conveyed in the direction from the destination position P.sub.destination to the start position P.sub.start, e) stopping the conveying device 4 after the product 3 has passed the retracted guide elements 6 and 6′ partially or completely.

(21) In order to obtain a plurality of measured values, the steps b) to e) are automatically run through a plurality of times in succession in each of the two work step sequences. A mean value for the dynamic measuring process and a mean value for the static measuring process are then determined in a further method step from the individual measured values. In yet a further method step, the mean values are compared with each other and the difference is stored as a correction value for the static-dynamic compensation.

(22) In the later regular weighing method, that is, after calibration of the weighing device, in which a plurality of products 3 are weighed dynamically in succession, the previously determined correction value is then added to each measurement result in order to decide on the actual weight.