SU1439410A1 - Automatic batch-type weigher with digital control - Google Patents

Abstract

The invention relates to a mass measuring technique and allows to increase the accuracy of the dosing of materials by eliminating the influence of errors introduced by the unstable physical parameters of the weighing system. The measurement is carried out in four cycles of operation of the control block 17. The first two cycles correspond to the position of the inductor 5 wound on a nonmagnetic frame 6, which is determined by the stop 13. In the first and third cycles the lower section of the coil 5 is connected to the input of the analog-digital converter 9 through the switch 8, in the second and fourth sections the upper section . Before the third and fourth strokes by heating the bimetallic plate 15 by the heating unit 16, the coil 5 is shifted to the position defined by the stop 14. The rod 4 with the ferromagnetic core 7 moves inside the coil 5 under the action of rotation of the micrometric screw 3 inside the nut 2 rigidly connected to the dial arrow pointer According to the results of measurements in four cycles, the arithmetic unit 10 calculates the mass value of the dose, which is compared in block 11 of the digital comparison with a predetermined value determined by the digital setting device 12, and if they coincide, the shutter of the dosing bin closes. 1 il. § SL CA9

Description

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The invention relates to a weighing equipment and can be used for the high-precision dosing of various materials, for example, the constituents of a concrete mix, a mixture and cores.

The purpose of the invention is to increase the metering accuracy.

The drawing shows the structure of the dispenser.

Soda dispenser, neighing a dial indicator having a housing 1 and equipped with a rotational angle converter of the arrow into linear movement containing a threaded pair of an exhaust 2 fixed on the needle of the digital pointer and micrometric screw 3 connected to the rotation restriction with the stem 4 of the linear converter displacements in the electrical signal. The latter contains a differential inductance coil 5 wound on a nonmagnetic frame 6, and a ferromagnetic core 7 fixed on the rod 4, In addition, a switch 8, an analog-digital converter (ADC) 9, the arithmetic unit 10 , digital comparison unit P, digital setting device 12, differential coil displacement unit, executed in the form of stops 13 and 4 and bimetallic plate 15, heating unit 16 and control unit 17,

The dispenser works as follows

In the initial state, under the action of the bimetallic plate 15, the inductor 5 is fixed in the extreme upper position defined by the stop 13. The materials of the metallic plate, its shape and geometrical dimensions are chosen such that the position of the coil is reliably secured for any changes in the medium temperature which may occur in the process of operation in the pre-service department. In the initial position at P 0, the heart 7 is set to the x position, symmetrical with respect to the 5 sections. When the dosing material enters the cargo receiving bin, the dial pointer pointer is deflected by an angle of 0 proportional to the current mass f, (P). The angle d is converted to whether the 1st displacement X fi (t) () is due to which

- 14394102

change inductance of L-each of., sensor sections as a function of movement

5 0 s

0 g e

L s (x)

For a positive conventionally accepted direction of movement of the core along the arrow in the drawing.

The measurement of mass P is carried out in four cycles. The first two cycles are conducted in the position of the inductor 5, determined by the stop 13. In the first cycle, the lower section of the differential coil 5, the electrical output signal N, is proportional to x - x via the switch 8 to the input of the ADC 9. In the second cycle, the upper section of the differential coil 5 is connected to the input of the ADC 9, the electrical output signal N is proportional to the value x + x.

At the end of the second measurement cycle, the heating unit 16 is turned on by the signal from control unit 17, as a result of which the inductance coil 5 is set to the lowest position defined by the stop 14 under the action of the bimetallic plate 15. The third and fourth measurement cycles are performed at this position.

In the third cycle, the lower section of the differential coil is connected to the ADC. The output electrical signal Nj is proportional to x p - x - where l is the known distance that the coil is shifted. In the fourth cycle, the upper section of the differential coil is connected to the ADP. The output signal is proportional to the value of x about + x +.

As a result of four cycles, the system of equations is obtained

N) -f bcd-x) + C5 N a (Ho - (- x) + b (Ho + x) + s;

N3 a (X (,) h-b (Ho-x- / 1) + s;

N

(x.) + b (xp + x4-L) + c.

where a, b, c are the coefficients of the conversion function 5 determined by the physical parameters of the weighing system and are random functions of time and destabilizing

314394

factors, the solution of which with respect to the measured value x gives

X

Ni - N4

(N,) - (N - N4)

or

R

 N4

(N - N3) - (N, - N4)

15

where -O is the proportionality factor j defined by the parameters of the mechanical units of the dial indicator.

Thus, the unstable coefficients ae b, c are not included in the final 20 expression for P and the metering accuracy is improved due to the exclusion of multiplicative and additive errors and nonlinearity errors. The accuracy of dosing depends only on the stability of the parameter and, which in the proposed device is set with any accuracy necessary for practice, using stops 13 and 14 "

Signal proportional to the calculation25

thirty

the secret current dose value P is fed to one of the inputs of digital comparing unit 5 11 to the second input of which a signal is proportional to a given dose from the output of the digital setting device 12. When the signals at both inputs of the unit 11 are equal, the signal for closing the inlet gate supply hopper.

Claims (1)

Claims of the invention An automatic portioning dispenser with digital control, comprising 394 ten 15 20 25 thirty 35 40  ABOUT u-gauge pointer with transforms; - the body of the angle of rotation of the arrow into a linear displacement, a linear displacement transducer, made in the form of a differential inductance coil wound on a nonmagnetic frame, and a rod with a ferromagnetic core, with the terminals of the differential inductance coil connected through a switch to the analog-p input if level converter S connected to an arithmetic unit, connected together with a digital setting device to a digital comparison unit, and a control unit, the outputs of which are connected to the terminal, 11M inputs of 5yms an atopa and an arithmetic unit, characterized in that, in order to improve accuracy, a displacement block for the differential induction coil, consisting of two stops on a large plate with a heating block, is inserted into it, and the stops and one end of the bimetallic plate are rigidly fixed to the dial pointer housing, its other end is connected to the nonmagnetic frame of the inductor, the inputs of the heating unit are connected to one of the outputs of the control unit, and the angle converter of the arrow turns into linear movement in the form of a threaded pair, the micrometric screw of which is rigidly connected to the stem, and the nut is rigidly connected to the arrow and mounted for rotation of the dial indicator housing and with restriction of movement along the axis of rotation, the stem with the ferromagnetic core and the screw being mounted on the coil of -ductance coaxially to the axis rotation of the arrow with the possibility of axial movement and with limited rotation.