METHOD AND APPARATUS FOR ANALYZING A MATERIAL FLOW

Abstract

A method and an arrangement for analysis of a material flow (S) is disclosed having one or more material components. The material flow (S) is conducted via a conveyor line. One or more acoustic sensors are allocated to the conveyor line. Acoustic signals produced by the material flow (S) are detected by the acoustic sensors and then converted into digital signals. The digital signals are analyzed in an evaluating unit in a computer-assisted manner and analyzed by means of an algorithm in comparison to reference values specified based on individual identifying characteristics of the material components, such that the material components are identified and the mass fraction of at least one material component in the material flow (S) is determined.

Claims

1-9. (canceled)

10. A method for analyzing a material flow, comprising: guiding the material flow over a conveyor section; wherein the conveyor section comprises a plurality of sound sensors, wherein the sound sensors are arranged on a contact element of the conveyor section or one of the contact elements integrated into the conveyor section; detecting the acoustic signals generated by the material flow through the plurality of the sound sensors; converting the acoustic signals into digital signals; providing an evaluation unit; comparing the digital signals using the evaluation unit to the reference values determined by individual recognition features of the material components; comparatively assessing the digital signals; identifying the material components; and, determining a mass fraction of at least one material component in the material flow.

11. The method of claim 10, further comprising detecting the acoustic signals and evaluating in the form of acoustic emission and/or structure-borne sound and/or airborne sound and/or liquid-borne sound.

12. The method of claim 11, further comprising calculating and evaluation one or more of the following parameters: Arithmetic mean Median Variance Standard deviation Effective value/RMS value (Root Mean Square) Quadratic mean/RMQ value RMX value Crest factor Bulge factor Maximum value Peak2RMS value Peak2Peak value.

13. The method of claim 11, further comprising detecting and evaluating individual bursts.

14. An apparatus for analyzing a material flow, comprising: at least one sound sensor; a conveyor section for moving the material flow relative to the plurality of sound sensors; wherein the conveyor section is part of a continuous conveyor or a continuous conveyor system; a contact element, wherein the at least one sounds sensor is arranged on the contact element; an evaluation unit, wherein the at least one sound sensor is linked to the evaluation unit, and wherein the evaluation unit includes an identification means for identifying the material components and the mass fraction of at least one material component in the material flow.

15. The apparatus of claim 14, wherein the at least one sound sensor is a sound emission sensor, a structure-borne sound sensor, an airborne sound sensor, or a liquid-borne sound sensor.

16. The apparatus of claim 14, wherein the at least one sound sensor comprises a plurality of sound sensors.

17. The method of claim 10, wherein the material comprises a plurality of material components.

18. The method of claim 10, wherein the conveyor section is part of a continuous conveyor or a continuous conveyor system.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0109] For an understanding of embodiments of the disclosure, reference is now made to the following description taken in conjunction with the accompanying drawings, in which:

[0110] FIG. 1 is a schematic diagram for one exemplary embodiment of a testing station;

[0111] FIG. 2 is a sectional view through FIG. 1 along the line A-A with a schematic embodiment of the measuring point I;

[0112] FIG. 3 is an enlarged view from the embodiment in FIG. 1 in the region of a contact element integrated into the conveyor section, and the measuring point II provided there;

[0113] FIG. 4 is a circuit diagram showing al processing when using the method according to the exemplary embodiment; and,

[0114] FIG. 5 is an example of an acoustic emission signal, showing the amplitude over time.

[0115] In the Figures, the same reference designations are used for identical or similar components, even if a repeated description is omitted for reasons of simplicity.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

[0116] Some embodiments will be now described with reference to the Figures.

[0117] Referring to FIG. 1, a conveyor section 1, which in the test setup shown, comprises a vibration chute 2, a conveyor belt 3 and a free-fall section 4. A mixture of materials in the form of a material flow S, containing a plurality of material components, is fed via a feeding unit 5 to the conveyor section 1. Several sound sensors 6, 7, 8, 9, 10, 11 are allocated to the conveyor section 1 (see FIGS. 2 and 3).

[0118] In the arrangement shown here, a first measuring point I is provided in the region of the vibration chute 2. At the measuring point I, below the floor plate 12 of the vibrating chute 2, an acoustic emission sensor 6 as well as a structure-borne acoustic sensor 7 and an airborne sound sensor 8 are set up. The bottom plate 12 of the vibrating chute 2, as well as its side walls 13, 14, form a contact element with which the material components of the material flow S come into contact. The sound. sensors 6, 7, 8 are placed under the floor plate 12 and do not come into direct or immediate contact with the material flow S itself.

[0119] From the vibrating chute 2, the material flow S reaches the conveyor belt 3 and is discharged at the end 15 of the conveyor belt 3 and falls freely over the free-fall section 4. The material flow S then meets a contact in the form of a baffle plate 16, which is integrated into the conveyor section 1.

[0120] The baffle plate 16 is inclined against the vertical, so that the material flow S occurs at the baffle plate 12 at an angle. A second measuring point II is set up on the baffle plate 16. For this purpose, sound sensors 9, 10 and 11 are set up on the rear side 17 of the baffle plate 16. The sound sensors 9, 10, 11 are also sound emission sensors, structure-borne sound sensors and/or airborne sound sensors.

[0121] The material mixture is fed as a continuous material flow S over the conveyor section 1. During the movement of the material flow 5, the individual material components, that is, the grains K of the material flow S, come into contact with one another. In addition, the material flow S comes into contact with the components of the vibrating chute 2, in particular its bottom plate 12 as well as the baffle plate 16. Sound emissions are generated via these. These processes furthermore create airborne and structure-borne sound emissions. The analysis of the material flow S can take place at the measuring point I as well as at the measuring point II. There, acoustic signals are recorded in the form of sound emission, structure-borne noise and/or airborne sound.

[0122] The measuring point I evaluates the material flow S while the vibration chute 2 is running. The oscillation of the vibrating chute 2 generates a plurality of impulses, which are used to evaluate the acoustic emission signal (Acoustic Emission), as well as the structure-borne sound and the airborne sound. FIG. 2 shows the structure-borne sound emissions with the arrows a. The airborne sound waves are marked with the letter b. The structure-borne sound waves are indicated by c. The structure-borne sound signals make it possible to observe changes in the stiffness of the system (vibrational chute and material flow or material components). With the help of all three of these pieces of information, statements can then be made regarding the material flow composition.

[0123] The measuring point II is located behind the conveyor belt the end of the free-fall section 4 on the baffle plate 16. The sound sensors 9, 10, 11 are set up on the rear side 17 of the baffle plate 16. The material flow S comes up against the baffle plate 16. During this contact of the individual material components of the material flow 5, the three sound signals can in turn then be observed or detected, namely, sound emission, structure-borne sound and airborne sound. Upon impact with the impact plate 16, the impact impulse is substantially larger, which can lead to other evaluation algorithms. The vibration of the baffle plate 16 can be included as a further determining feature in the recognition and evaluation.

[0124] FIG. 3 shows an impact of the grain K of a material component of the material flow S onto the baffle plate 16. Upon impact, sound emissions are converted into the impact impulse from the destruction of the material and the impact. This is illustrated by the letter a. Airborne sound waves that are generated by the process, are indicated by b. Structure-borne sound vibrations of vibrating chute 2 and baffle plate 12, as a function of the stiffness, are indicated by the arrows c.

[0125] Although there are three sound sensors 6, 7, 8 at the measuring point I and three sound sensors 9, 10, 11 at the measuring point II in the sample setup described here, a sound sensor 6, 7, 8, 9, 10, 11 can be sufficient to detect the signals generated by the material flow S. The combination of a plurality of sound sensors 6-11 in the region of a measuring point is, however advantageous.

[0126] The acoustic signals generated by the continuous movement of the material flow S and recorded over the sound sensors 6-11 are amplified by means of an amplifier 18 (see FIG. 4) and converted into digital signals. An analog-to-digital converter 19, also called A/D converter, is provided for this purpose. An evaluation unit 20 connected to the system performs a computer-assisted evaluation of the digital signals by means of an algorithm. The results are compared to reference values determined based on individual identification characteristics of the material components. For this purpose, the system is programmed for a plurality of material components or, depending on the application or specific case, for the expected material components. The reference values are stored in a database which can be accessed by the evaluation unit 20, and which belongs to the system. The system can recognize patterns, repetitions, similarities and lases in the set van data and to compare these with the reference values stored in the system. This information is used to identify the material components as well as to determine the mass fraction of one or more material components of the material flow S. In terms of the practical tests, the density of the material components has been proven to be a particularly beneficial recognition characteristic.

[0127] As already explained, FIG. 5 represents an AE signal over time, by showing changes in amplitude over time. The bursts have a characteristic signal form. The purpose of the evaluation of the AE signals is to compare the digital signals with reference values which are determined on the basis of individual recognition characteristics of the material components. This is done by means of algorithms. The algorithm or the algorithms include the evaluation and assessment of the parameters set forth in Claim 3 (RMS, Peak2Peak, Peak2RMS, etc.). Reference values derive from the bursts as well as maximum amplitude, rising time, decay time, duration of a burst) can also be used to determine the material distribution.

[0128] The system is based on the evaluation of several bursts, which result from the movement of the material flow over the conveyor section. The bursts or their wave forms and wave patterns are evaluated. This requires the identification of meaningful features. This is used for the determination (extraction) of the AE features and the generation of an AE data set for each burst. The determination and evaluation may include the following AE features: [0129] arrival time (absolute time of the first threshold crossing) [0130] maximum amplitude [0131] rise time (time interval between the first crossing of the threshold and the time of the maximum amplitude) [0132] decay time [0133] signal duration (time interval between first and last crossing of the threshold) and also [0134] overshooting of a hit or count (number of times that the threshold is crossed in one polarity) [0135] energy (integral of the squared or absolute instantaneous values of the voltage profile) [0136] RMS (effective value) of the continuous background noise for the corresponding hit.

[0137] The foregoing description of some embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The specifically described embodiments explain the principles and practical applications to enable one ordinarily skilled in the art to utilize various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto, and their equivalents. Further, it should be understood that various changes, substitutions and alterations can be made hereto without departing from the spirit and scope of the invention as described by the appended claims.