SU731302A1 - Method of monitoring the error of continuous weighing - Google Patents

Description

The invention relates to the field of weighing equipment and can be used in whitefish: fishing topics for weighing and dosing bulk and lump materials, in particular molding materials used in foundries using weighing conveyors. Methods are known for monitoring the continuous weighing error, which means that at the time of control, the material is stopped on the weighing conveyor and the linear load without material is measured as well as when comparing the mass of the same portion measured in the control cycle intermediate weight bunker and B checked weight balancer 1. The disadvantages of these methods are the violation of the continuity of the flow of the dosing material (in the first case), as well as the need to introduce additional A weight gauge that in certain cases may be unacceptable. Closest to the proposed by the technical nature of the method of controlling the error of continuous weighing, which consists in determining the difference between the mass of the material, equal to the product of the speed of movement of the material on the linear load of the tape weight measurement with a controlled value of 2. The disadvantage of this method is the need to interrupt the flow of materials, which in many cases x is not allowed by technology. In addition, the implementation of the method is associated with the additional installation of a flow interrupter and hopper scales, which occupy a considerable height, which limits its applicability. The purpose of the invention is to determine the weighing error while maintaining the continuity of the flow of the material to be measured and to expand the scope. To achieve this goal, the controlled value of the mass of the material is set by varying the speed of the tape of the weight gauge and the new value of the mass of the material is measured, and the error of weighing 51 is determined as the ratio of the mass difference

material to the difference in speeds of movement of the tape.

The drawing shows the stages of work according to the preliminary method, where -1 is the measurement of the mass of the dosed material at the speed of the weighing conveyor /. ; 2 - change of the speed of the weighing conveyor from V, (k V2; 3 - time delay by the magnitude of the transition process; 4 - measurement of the mass of the dosed material t at the speed of the weighing conveyor Vg; 5 - calculation of the dosing error using the formula

VVa.

The essence of the methods by which a positive effect is achieved and the output of the calculation formula is considered on the example of a dispenser with a separate weighing conveyor.

Let the flow rate of the material coming from the feeder of the metering device to the weight meter be constant and equal to

o, m-v. .GA

t-de V - the speed of the tape weight;

t, is the measured per unit load of the material on the weight meter tape. In belt weighing instruments and metering devices with a single weight conveyor, the velocity V is constant, and the flow rate p is measured by the value of the linear load t.

If you change the speed of v / tape. the weight meter to the speed Vg (without changing the flow rate of the material P coming from the feeder of the metering device), then the linear load will also change and will be equal to n, while

flow p, 2. g then u, gpd j. rrt,.

If in the process of dosing the material sticks on the weight measuring device U L1 (the value of sticking at the moment does not depend on the flow rate p and the speed of the tape of the weight measuring device V), then

Y (& t V lrrij - e).

Solving an equation for m get

dt

The proposed method can be applied to determine the measurement error of both individual weighing instruments and metering devices in which there is a separate weighing conveyor.

For this, the value of mass, m, at the speed of the weight meter conveyor, is measured and recorded in a computing device by the indications of the secondary instrument of the weight meter; the speed of the weighing conveyor varies from V to V

(moreover, V and Vj are fixed speeds); provide a time delay before the weighing unit measures a uniform layer of the material being metered on the conveyor; According to the indications of the secondary instrument of the weight gauge, the mass in the computing device determines the dosing error according to a known dependence.

jMV

in, shv, -v

in dispensers, to improve the accuracy of continuous dispensing, the magnitude of the computational error can be entered as corrections in the controller.

Claims (2)

Invention Formula The method of controlling the error of continuous weighing, which consists in determining the difference between the mass of the material is equal to the product of the speed of movement of the material by the linear load of the tape weight-measuring device with a controlled value, different By the fact that, in order to determine the weighing error while maintaining the continuity of the flow of the material being measured and expanding the scope of application, the monitored quantity. by changing the speed of movement of the tape of the weight gauge and measuring the new value of the mass of the material, and the weighing error is determined as the ratio of the difference of the mass of the material and the difference of the speeds of movement of the tape. Information sources, taken into account during the examination - 1. Automation of dosing processes in metallurgy. Ed. Shidlovich L.Kh. M., Metallurgists, 1977, p. 345. 2. USSR author's certificate No. 501293, cl. D 01 Q 11/00, 1974 (prototype).