METHOD FOR DETERMINING A MASS FLOW AND CONVEYING AND MEASURING DEVICE

Abstract

A method for determining a mass flow of bulk material in a conveyor line includes providing a conveyor line, continuously receiving bulk material, transporting the bulk material on the conveyor line, and discharging the bulk material at an end point of the conveyor line. The conveyor line includes an array of weighing cells having a plurality of weighing cells successive in a direction of transport.

Claims

1. Method for determining a mass flow of bulk material in a conveyor line, including the following steps: providing a conveyor line including an array of weighing cells consisting of a plurality of weighing cells successive in a direction of transport (ST1), continuously receiving bulk material, transporting the bulk material on the conveyor line in the direction of transport across the plurality of weighing cells, discharging the bulk material at an end point of the conveyor line (ST2), putting out measuring values of the individual weighing cells as a function of time (ST3), evaluating with comparisons of measuring values as a function of time and a position of the weighing cells in the direction of transport, determining a mass flow from the evaluation (ST5).

2. Method according to claim 1, characterized in that distance values of the weighing cells in the direction of transport in relation to one another are included in the determination.

3. Method according to claim 1, characterized in that when comparing the measuring values a structure or sequence of measuring values of spatially successive measuring values of a first measurement at a first point in time (t0) is compared with at least one structure or sequence of measuring values of spatially successive measuring values of a second measurement at a second point in time, and a distance value of the two structures or sequences of measuring values is determined from the comparison, and the mass flow is determined from the distance value and the time difference between the first point in time and the second point in time.

4. Method according to claim 3, characterized in that first a transport velocity is determined from the distance value and the time difference and subsequently the mass flow is determined from the transport velocity and the measuring values.

5. Method according to claim 1, characterized in that at at least two points in time each a one- or multi-dimensional matrix of measuring values is created, and from the at least two matrixes a pattern recognition and/or a correlation, is carried out to determine matches in the structures or sequences of measuring values.

6. Method according to claim 5, characterized in that with one time difference in each case the autocorrelation is carried out with different distance values, and the correct distance value is recognized in the autocorrelation with a highest significance.

7. Method according to claim 1, characterized in that the array of weighing cells is designed as a one- or multi-dimensional matrix consisting of weighing cells arranged successively in the direction of transport.

8. Method according to claim 1, characterized in that the conveyor line is selected from the following group: belt conveyor, screw feeder, vibration conveyor, deflector plate conveyor, cellular wheel conveyor.

9. Method according to claim 8, characterized in that when utilized as a deflector plate conveyor, weighing cells are provided immediately below the deflector plate and/or integrated therein, where measuring values of a front weighing cell are used to determine a particle mass of the impinging material, and further, the slippage characteristics is determined as transport velocity from the subsequent weighing cells.

10. Transporting and measuring device for transporting and measuring a mass flow of bulk material, the transporting and measuring device comprising: a conveyor line adapted to transport bulk material as a mass flow (W) from at least one starting point in a direction of transport up to an end point, an array of weighing cells consisting of a plurality of weighing cells, arranged successively in the direction of transport, each detecting a mass load, and put this out as a measuring value as a function of time, an evaluation device adapted to evaluate the measuring values as a function of time and a position of the weighing cells in the direction of transport.

11. Transporting and measuring device according to claim 10, characterized in that the evaluation device is designed to compare the structure or sequence of measuring values of spatially successive measuring values of a first measurement at a first point in time with at least one structure or sequence of measuring values of a second first measurement at a second point in time, and to determine a distance value or spatial offset of the two structures or sequence of measuring values from the comparison.

12. Transporting and measuring device according to claim 10, characterized in that the conveyor line is designed as a belt conveyor including a conveyor belt under which or integrated in which the plurality of weighing cells is arranged.

13. Transporting and measuring device according to claim 10, characterized in that it is designed as a screw feeder including a screw conveyor, the weighing cells being provided in a lower floor area and distributed in areas successive in the circumferential direction.

14. Transporting and measuring device according to claim 10, characterized in that it is designed as a vibration conveyor, wherein the plurality of weighing cells are provided in the plate elements actuated by a vibration means or as plate elements.

15. Transporting and measuring device according to claim 10, characterized in that it is designed as a deflector plate conveyor including a downward sloping deflector plate, where the weighing cells are provided under the deflector plate or integrated therein.

16. Transporting and measuring device according to claim 10, characterized in that at least some of the weighing cells are designed as an element from the group consisting of piezo sensors and/or wire strain gauges, and coating or part of a coating including individual weighing cells.

17. Transporting and measuring device according to claim 10, characterized in that a transmission of the measuring values and/or of energy from and to the weighing cells is provided to be wireless and/or by means of passive transponders.

18. Transporting and measuring device according to claim 10, characterized in that the plurality of weighing cells is arranged as a one-dimensional line array or multi-dimensional matrix, including weighing cells successive in the direction of transport.

19. Method for regulating a mass flow, wherein using a method according to claim 1 a bulk material is transported from the bulk material feed provided at the starting point to a receiving or processing means provided at the end point and measured, and the mass flow on the conveyor line is determined, and the bulk material feed and/or the receiving or processing means is controlled and regulated depending on the determined mass flow.

20. Method according to claim 19, characterized in that the bulk material feed is controlled depending on the determined mass flow in such a manner that a prescribed mass flow is adjusted.

21. Method according to claim 19, characterized in that the receiving or processing means is controlled depending on the determined mass flow, whose transport velocity or production speed is regulated depending on the mass flow.

22. Method according to claim 19, characterized in that the following is fed in as bulk material: a plastics material and/or rubber material, and one or more additives, where the mass flow of the plastics material and/or rubber material and/or the mass flow of the one or more additives is measured and regulated.

Description

[0045] The invention is illustrated below by means of the attached drawings by means of a few embodiments. It is shown in:

[0046] FIG. 1 a transporting and measuring device according to one embodiment;

[0047] FIG. 2 measuring signals of the sensor channels at successive measuring times;

[0048] FIG. 3 an embodiment with a belt conveyor.

[0049] FIG. 4 an embodiment with a screw feeder;

[0050] FIG. 5 an embodiment with a vibration conveyor;

[0051] FIG. 6 an embodiment with a deflector plate; and

[0052] FIG. 7 an embodiment with a cellular wheel conveyor.

[0053] According to FIG. 1 a conveyor line 1 in a production plant 2 is provided. Die production plant 2 comprises, for example, a bulk material feeder 3 with a collecting funnel for feeding granulated bulk material 4. As bulk material 4, for example, pellets, granulate, powder or flakes may be fed-in. Thus, the bulk material 4 reaches the conveyor line 1 and is transported on the conveyor line 1 from one or more starting points A in the direction of transport F to an end point B, for example, to a processing unit 5, e.g., an extruder putting out a processed product 7. Hereby, the bulk material feeder 3 and processing unit 5 are named by way of example only because, in principle, the transport of bulk material 4 may be provided for other purposes also.

[0054] On the conveyor line a weighing cells matrix 9 consisting of weighing cells 8 is provided, which is designated in FIG. 1 along the direction of transport F as X1 through Xn. In this embodiment, the weighing cells matrix 9 is designed as a line array, i.e., as a one-dimensional arrangement of the weighing cells X1 through Xn which are directly successively in the direction of transport F. In other embodiment, two- or multi-dimensional arrays may be provided, i.e., including two or more weighing cells in the depth direction perpendicular to the drawing plane.

[0055] Each weighing cell Xi, i=1n measures the weight acting on the conveyor belt 6 as a measuring value Mi, i=1 through n. Advantageously, the weighing cells X1 through Xn are provided directly beneath the conveyor belt 6, without any further static downwards support of the conveyor belt 6, so as to provide a measuring value Mi of utmost precision. However, the weighing cells X1 through Xn may also be, e.g., integrated into the material of the conveyor belt 6.

[0056] FIG. 2 shows in two diagrams a) and b) each the measuring value M as a function of the spatial coordinate X along the direction of transport F, i.e., as M(x). Hereby, the measuring values M(x) change over time; the upper diagram a) shows the measuring values M(x) at a point in time t0; the lower diagram b) shows the measuring values M(x) at a subsequent point in time t1=t0+Delta-t, i.e., later about a value Delta-t. As apparent from FIG. 1, the bulk material 4 lies on the conveyor belt 6 not evenly but, rather, forms specific warping and clumping in the direction of transport F. Thus, in the upper diagram a) of FIG. 2, the individual measuring values M(x) or M1-Mn respectively differ in accordance with the patterns of warping; a specific pattern is formed.

[0057] Upon transporting the bulk material 4 via the conveyor belt 6, depending on the design of the conveyor line 1, at first the warping will change only slightly and, therewith, the material accumulations of the bulk material 4 will be re-distributed only to a small extent. Thus, the formation of masses or the pattern respectively shown in FIG. 1 will be conveyer further along the direction of transport F.

[0058] Thus, as can be seen from the diagrams a) and b), the characteristic formations of warping or patterns or mass accumulations respectively are transported further along over time so that the sequence of measuring values Mi or M(x) respectively remains essentially constant, but being shifted further along via the measuring channels in the direction of transport F. Thus, the time difference Delta-t between diagrams a) and b) corresponds to a channel difference or, respectively, a distance value Delta-X in the signal diagrams of FIG. 2. Hereby, the correlation between Delta-x and Delta-t results in the transport velocity v, i.e., v=Delta-x/Delta-t. Thus, this transport velocity v can be determined with higher accuracy than, e.g., a belt velocity roughly deduced from the rotations speed of the deflector rollers 14, because the actual belt velocity may depend on slippage at the deflector rollers occurring depending on the tension of the elastic conveyor belt the load caused by the mass.

[0059] From FIG. 2 a correlation of the measuring values at time t0 and t1 is formed, i.e., an autocorrelation of the measuring signal M(X), across different distance values Delta-X, until the highest significance is determined. Thus, in FIG. 2 a one-dimensional autocorrelation is carried out. Depending on the design as a line array or multi-dimensional matrix it is also possible to carry out, e.g., a 2D autocorrelation.

[0060] Thus, it is possible from the measuring signal Mi(t), for one thing, to directly detect the mass in the individual channels X1-Xn, and, for another, to determine the transport velocity v via the conveyor line 2. Thus, it is possible to detect the mass flow W(t) of the bulk material 4 from these two pieces of information as a function of time t.

[0061] Thus, in particular, a regulation or controlling may be carried out depending on this determination. Thus, in particular, the mass flow W(t) can be measured via the conveyor line 2, and the bulk material feeder 3 may be controlled depending on the mass flow W(t), so as to regulate the mass flow W(t). Furthermore, it is also possible to control the processing unit 5 so as to receive the respective mass flow W(t).

[0062] The FIGS. 3 through 6 show embodiments of various conveyor lines 1: In FIG. 3, a belt conveyor 10 is shown, wherein the measuring principle of FIG. 1 can be realized directly, i.e., the weighing cells 8 are provided, in particular, underneath the conveyor belt 6, since the conveyor belt 6 passes the acting weight directly on to the weighing cells 8. Thus, in this case, it is possible to control the deflector rollers 14 so as to adjust the belt velocity.

[0063] In FIG. 4, a screw feeder 11 is shown, wherein weighing cells 8 may be provided distributed in circumferential directions, i.e., both below the screw conveyor 12, as well as in further places on the circumference, i.e., laterally and even above, because in the screw feeder 11 the bulk material 4 is pushed radial outwards and measurements can therefore be made on the circumference. Thus, in this case, a multi-dimensional array of weighing cells 9 may be provided. Thus, in such a screw feeder 11 it is possible to detect successive sensor channels in the screw direction, i.e., successive with an offset in the direction of transport F and circumferential direction in accordance with the screw-type or, respectively, helical motion of transport.

[0064] FIG. 5 shows a vibration conveyor 18 or, respectively, a vibrating plate, wherein the weighing cells 8 may be provided directly in the plate elements 20 addressed by the vibration generator 19, or the weighing cells 8 serve directly as plate elements 20 thereby directly detecting the measuring value Mi. In addition to the weight the vibrations are detected, which at first deliver high contributions compromising the measuring results; however, these can be deducted as known or, respectively with a known temporal signal so as to allow for high accuracy measurements.

[0065] According to FIG. 6, a deflector plate conveyor 16 is shown, wherein the bulk material 4 is collected on a deflector plate 17 and slips downwards via the deflector plate 17. Hereby, appropriate weighing cells 8 may be provided directly beneath the flexibly designed deflector plate 17.

[0066] FIG. 7 shows an embodiment with a cellular wheel conveyor 24 which receives, as a rotation conveyor, a mass flow W at an upper inlet 25 of its housing 26, transports it via individual cells 28 of its rotating drum 29, and discharges it at an outlet 30. Hereby, the weighing cells 8 may be provided, for one thing, on the housing 26, e.g., according to FIG. 7, in a lower position or 180° position respectively of the housing 26, where the bulk material 2 rests at the bottom of the housing 26. Furthermore, or in the alternative, the weighing cells 8 may be provided on a blade element 32 of the rotating drum 29, e.g., at a 90° position, where the bulk material 2 rests on the horizontal blade element 32.

[0067] In this embodiment, as well as on others, the transmission of the measuring values M and the energy between the weighing cells 8 and a transmitter and receiver unit 34, in the case of rotating or moving parts, may also occur in the form of wireless signals 36, e.g., using NFC technology or by designing the weighing cells 8 as passive transponders.

[0068] The array of weighing cells 9 may be designed as a coating 35 or part of a coating 35 which, consequently, may be attached in suitable areas, in particular, on the static housing and/or on moving parts. Thus, such a coating 35, e.g., in FIG. 7, may be provided on a blade element 32, or even, as in FIG. 6, on the deflector plate 17.

LIST OF REFERENCE NUMERALS

[0069] 1 conveyor line [0070] 2 production plant [0071] 3 bulk material feeder (e.g., collecting funnel) [0072] 4 bulk material [0073] 5 processing unit, for example, extruder [0074] 6 conveyor belt [0075] 7 processed product [0076] 8 weighing cell [0077] 9 weighing cells-Matrix, e.g., array of weighing cells [0078] 10 belt conveyor [0079] 11 screw feeder [0080] 12 screw conveyor [0081] 14 deflector rollers of the belt conveyor [0082] 16 deflector plate conveyor [0083] 17 deflector plate [0084] 18 vibration conveyor [0085] 19 vibrator, vibration generator [0086] 20 plate elements [0087] 24 cellular wheel conveyor [0088] 25 upper access to the housing 26 [0089] 26 housing [0090] 28 cells of the cellular wheel conveyor 24 [0091] 29 drum [0092] 30 outlet of the housing 26 [0093] 32 blade element [0094] 34 transmitter and receiver unit [0095] 35 coating, e.g., sensor foil [0096] 36 wireless signals [0097] A starting point [0098] B end point [0099] M1 . . . Mn measuring values [0100] Xi, i=1n weighing cells, measuring channels [0101] F direction of transport [0102] V transport velocity [0103] W mass flow [0104] t0 first point in time [0105] t1 second point in time [0106] Delta-t time difference between t0 and t1 [0107] Delta-X distance value, spatial offset