DD260764A1 - METHOD FOR DETERMINING THE COOLING RATIO OF A GRAIN MIXTURE - Google Patents

Abstract

The invention relates to a method of continuous monitoring or control of the Koverungsverhaeltnis Schuettgueternes. Several Koerner side by side, with a distance to each other are guided at a predetermined uniform speed at right angles in front of a CCD line sensor through a parallel band of light, the CCD line sensor cyclically scans the Koerner line by line, thereby the uninterrupted sequences of pixels (tendons), which signal the widths of the individual grain sections, classified into classes of different chord lengths. These classes in relation to each other give, compared with a calibration function, the Koernungszahl.

Description

Sequence the grains scanned line by line, thereby the uninterrupted sequences of pixels (tendons), which signal the widths of the respective grain sections are classified into classes of different chord lengths, these classes when reaching a fixed count or a count time in a certain ratio, with a calibration function , compared, gives the grain count.

Depending on the grain composition and the grain width, the individual chord lengths can be arranged in two or more classes, compared with each other and compared with the calibration function.

The method guarantees a quick detection of an unknown graining ratio, a quick determination of the grit number and allows in a technological process a quality processing of a grain mixture with prescribed grain fractions.

embodiment

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FIG. 1: Flow chart of a device arrangement for carrying out the method. FIG. 2: Screening curves of the grain samples A, B, C, which were determined using conventional sieves of standardized mesh sizes.

Figure 3: Tendons of grains of different sizes as a function of the scanning cycles (n-4) to η Figure 4: determined tendon distribution Figure 5: dependence of the grain count on the tendon ratio.

With the device arrangement shown schematically in Figure 1, the inventive method for determining the grain number of a concrete aggregate with a grain size of 0.25 ... 16 mm 0 will be explained in more detail. From the aggregate, three samples A, B, and C are first assembled by sieving with the sieve passages shown in FIG. 2 for calibrating the measuring arrangement. Sample A contains a coarse grit having a grain size K _A = 4.75, sample B contains an average grain size of K _B = 4.00 and sample C has a fine grain size of K _c = 3.35. 100 g of each sample are treated as follows:

From the Meßgutförderband 1 pass the grains of the sample A in free fall outgoing from the illumination device 2 horizontal band parallel light radiation. It fall through several grains next to each other, but optically separated from each other, the light band. This assumes that the preparation of the material to be measured is done so that agglomeration of the grains is avoided. As they pass through the light band, the grains produce shadows on the ground-glass screen 3, which are detected by the CCD line scan camera 4. In this case, the CCD line scan camera 4 cyclically scans the light band on the ground glass in a constant, fast sequence. The drop height and the cycle time are chosen so that the smallest grains are detected with sufficient accuracy. The drop height in the example is 51 mm and the cycle time is 120 ps. The luminous intensity profile of the line is projected at a magnification β '= -0.4125 onto the sensor with 1024 pixels, of the dimension 13 χ 13 μm, detected by the sensor and binarized by a subsequent comparator.

Brightly or darkly scanned pixels leave line by line the CCD line scan camera 4. Uninterrupted dark scanned pixels (chords) are added by the counting circuit 5. A chord represents the width of a grain in a discrete grain section, as shown in FIG.

For the further procedure, the assignment of the tendons to the individual grains is meaningless. They are subdivided lengthwise in the sorting circuit 6 into two classes (I, II), the short chords a (0.125 <a <2 mm) of class I and the long chords b (2 <b <16 mm) of class II be assigned. '

The resulting short tendons a are added in the counter 7 and the long tendons in the counter 8. FIG. 4 shows the number of sinews as a function of the chord length

 When the total amount of the sample is scanned, the divider circuit 9 forms the chord ratio Q from the sums a and b

(- = Q). For the test sample A with a grain size of 4.75, the chord ratio Qa = 17.8. This value is displayed in b

Calibration memory 10 stored.

Likewise, Samples B and C are used to determine tendon conditions. For the sample B, the chord ratio Q _B = 50.9 and for the sample C the chord ratio Qc = 72.7 · Q _B and Q _c are also stored in the calibration memory 10.

The dependence of the chordal ratio of the grain number shows Figure 5, which also forms the calibration function of the method for determining the grain size of large-scale processed concrete aggregate with the grain band 0.25 ... 16mm0 in concrete production. From any number of samples of the aggregate, the grain count can be determined quickly and easily and during the concrete production process, the aggregate can be monitored and controlled in its composition.

If the measured grain count deviates from that required in the recipe, the grain-belt-improving fractions are admixed.

Claims (1)

- 1 - ZOU / 04 Claim: Method for determining the grain ratio of a grain mixture in which a Komprobe is taken from the grain mixture continuously or discontinuously, from which the grains isolated over a transport device, at right angles, optically separated moved past a CCD line sensor and the case sampled pixels are further evaluated , characterized in that a plurality of grains side by side, at a distance from each other, at a predetermined uniform speed in front of a CCD line sensor through a parallel light band are guided, the CCD line sensor cyclically in a constant, rapid sequence, the grains scanned line by line, while the uninterrupted Sequences of pixels (sinews) which signal the widths of the respective grain sections are classified into classes of different chord lengths, these classes upon reaching a fixed count or a count time in a predetermined ratio s to each other, compared with a calibration function that gives the grain count. For this 3 pages drawings field of use The invention relates to a method of continuously monitoring or controlling the graining conditions of bulk materials, such as concrete aggregates, sands, seeds, fertilizers and the like, in particular during the technological process. Characteristic of the known state of the art In addition to the mechanical test sieving, a number of other continuous methods for determining the particle size distribution in mixtures are known. Favorable prerequisites are offered by optoelectronic scanning for the geometrical dimensioning of particles or particle mixtures and the evaluation electronics, with the help of which the particle size distribution is determined. DE-OS 3510363 describes a device with which from a production stream of solid particles continuously or stepwise, the size distribution of these particles are examined such that they are successively in a measuring channel in free fall on an optoelectronic sensor, for. B. a CCD line sensor are passed and scans the example produced by a light source shadow image of a particle. An evaluation transmitter connected to the sensor samples the line consisting of the photoelements (pixels) at a frequency. The particle is detected several times during its movement. The number of unexposed pixels is counted and the highest number corresponding to the maximum particle diameter is registered. The evaluation electronics together with the number of measured particles form their size distribution. This procedure adheres to the disadvantage that only one particle may be detected by the optoelectronic sensor. The expenditure on equipment for separating is high, and the device for scanning is not busy. The analysis time for a sample is too long to intervene in a continuous production process control technology. Another measurement of the grain size distribution of granular masses by processing static images of the grains of a collective which continuously passes a certain drop height is disclosed in DE-OS 2855583. The grain granulometric data obtained from the image, such as diameter, projected area and total number The grains appearing in a picture are used to convert the particle size distribution. The distribution can also be determined as the mean value of the observed values. As an intermediate result of the information processing, the grain must always be present as a static image. As the scanned images are processed, grains pass unmeasurably through the device. Thus, the test samples are not representative of the entire Körnungsgut. It can also be analyzed only a few Meßgut per measuring unit, so that the measuring power is low. With the invention, the grain ratio of a grain mixture in real-time operation is to be determined by a rapid procedure in order to formulate the required grain band for quality-related further processing. Essence of the invention Der'erfindung the object of the invention is that in a small time unit of a lot of Meßgut the grain ratio without knowledge of the single grain, can be determined with a low information processing effort. With a Komprobe which is taken from a grain mixture continuously or discontinuously and the grains isolated over a transport device, perpendicular, optically separated moved past a CCD line sensor, the pixels thereby sampled are further evaluated, ^ the object according to the invention thereby achieved in that a plurality of grains are guided side by side, at a predetermined uniform speed at right angles in front of a CCD line sensor through a parallel light band, the CCD line sensor cyclically in a constant, faster