RU2085521C1 - Method of weighing of loose materials - Google Patents

Abstract

FIELD: weighing equipment. SUBSTANCE: method may find use in weighing lines of various components, for example, of components of glass charge. Unloading of each partial weight is carried out with remaining portion of material. Setting of remaining mass for all portions of material but last one is specified provided that Po P_o>P_т ft and setting of remaining mass of last portion is specified on condition that

Description

 The invention relates to a weight measuring technique and can be used in dosing lines of various components intended for further mixing, for example, in the preparation of a glass charge.

 When preparing a glass charge on dosing and mixing lines, seven to eight different components are discharged from the corresponding dispensers to an assembly conveyor, through which they are fed to the mixer. The main criteria for the effectiveness of dosing and mixing lines are productivity and dosing accuracy. To increase the productivity of the dosing process, a method is increasingly being used in which components are loaded into the dispenser in an intensive feed mode. To increase the accuracy of dosing, the material is unloaded from the dispenser first in intensive and then in slow motion.

 The accuracy of unloading the material from the dispenser is increased if the dispensing is carried out not with the complete unloading of the material, but with a residual "tare weight", which takes into account the sticking of the material to the walls of the dispenser, after unloading the specified weight.

 To reduce the material consumption of dosing equipment while maintaining productivity and accuracy, partial dose dosing is currently being used, at which the mass of each dose is equal to the quotient of dividing the specified mass by the number of partial doses. Obviously, this reduces the dimensions of the dispensers and the dosing and mixing line, which is important in the reconstruction of existing dosing and mixing workshops. But with a decrease in the partial dose, it is more difficult to reduce the relative dosing error when using the partial dose dispenser in the weighing mode, when the material that is loaded is completely unloaded from the dispenser. Therefore, of interest is a method of dosing in partial doses with a residual "tare weight".

A known method of weight dosing of bulk materials, including setting the desired dose weight and maximum dose weight, loading the material pose, comparing the current weight value with setting the dose weight, stopping the dose loading when these values are equal, comparing the actual dose weight with the maximum dose weight and implementation of dose unloading if the actual dose mass does not exceed the maximum dose mass, or the prohibition of unloading if the actual dose weight exceeds the maximum dose mass , measuring after unloading a dose of the residual mass of the material and setting its setpoint, adjusting the setpoint of a given mass by the value of the setpoint of the residual mass, unloading the main part of the dose with coarse and accurate flows at the same time, and then the remaining part of it with an exact flow only, comparing the current value of the remaining mass of the dose with the set point of the residual mass and, if they are equal, the termination of unloading, a decrease in the set point of the residual mass to increase the time for unloading the dose, or increase it to reduce the time narrow [1]
The disadvantage of this method is that it is more suitable for dosing a given mass of material in one cycle "loading-unloading" and less for dosing in private doses.

The closest technical solution to the proposed one is a method of dosed feeding the components of a glass mixture, including feeding a dose in parts of a mass equal to the quotient of dividing a given mass of a dose by the number of parts, determining the mass of material being unloaded after each part is fed, calculating the difference between the given dose mass and the mass of unloaded material, adjusting the mass of the last part, the supply of all parts except the last, in the intensive feed mode, determining the difference between a given mass and mass unloaded material before feeding the penultimate part and when the difference value is less than twice the mass of the given part, the plumb of the last part is reduced by the value of the smallest dosing limit, the last part is fed first in intensive mode and then in slow motion [2]
The disadvantage of this dosing method is that it does not take into account the change in the physical properties of the dosed material. In addition, the known method does not take into account the possible residual mass of the material. Both of these factors lead to a decrease in metering accuracy. It should also be emphasized that the application of this method completely eliminates dosing with residual material, since it is limited by the smallest dosing limit, which in this case can be greater than the residual mass of the material.

 The main task of improvement is improving the accuracy of dosing.

P_о остаточная масса материала;
P_т оставшаяся часть дозы;
P_з заданная масса дозы;
σ максимальная погрешность загрузки в процентах;
n число частей.Another objective of the improvement is increasing the dosing rate. This is achieved by the fact that in the known method of weighing dosing of bulk materials, including loading the dose in parts of a mass equal to the quotient of dividing a given mass of dose by the number of parts, determining the mass of unloaded material after unloading each part, calculating the difference between a given dose mass and the total mass of unloaded material , adjusting the mass of the last part, supplying all parts except the last in the intensive unloading mode, supplying the last part first in intensive and then in slow motion Flash modes, each partial discharge of the dose is carried out with a net weight of the material, wherein all parts except the last setting of the residual mass is set _{on the} condition P> P _t, and the residual mass for setting the last dose is set based on the condition

P _{about the} residual mass of the material;
P _{t the} remainder of the dose;
P _s set dose weight;
σ maximum load error in percent;
n is the number of parts.

.The difference between the proposed technical solution and the prototype is that each partial dose is unloaded with the residual mass of the material, and in addition for all parts except the last, the residual mass is set from the condition P _о > P _t , and the residual mass for the last dose is set based on terms

.

 In the known technical solutions, such a combination of features is absent. Using this set of features will improve the accuracy of dosing due to the bilateral unloading of the last partial dose and taking into account the residual mass of the material; it will allow to unload all parts except the last one by different settings of the residual mass of the material in an intensive mode, which further increases the productivity of the dosing process, since loading all parts of the reference is intensive.

 In addition, all parts are loaded and unloaded with a given intensity without additional control action, but only due to the design features of the dispenser and different settings of the residual mass of the material.

 In FIG. 1 shows a device that implements the method of weight dosing of bulk materials; in FIG. 2 moment of the beginning of the unloading of a partial dose from the dispenser to the assembly conveyor; in FIG. 3 the moment of the beginning of the unloading of the material remaining in the “rough” and “accurate unloading” chambers; in FIG. 4 - the moment before the end of the unloading of the material of all parts except the last; in FIG. 5 moment of the end of unloading of all parts except the last; in FIG. 6 - the moment of transition to the "exact" unloading mode for the last part; in FIG. 7 - the moment of the end of the unloading of the last part; in FIG. Fig. 8 loading schedule - unloading of partial doses depending on the value of the residual mass of the material (residual "tare" weight) with the number of parts n 4.

A device that implements the method consists of a suspension bunker 1; weight batcher 2; feeder 3 downloads; feeder 4 unloading; partitions 5; dividing the lower part of the weighing batcher 2 into two chambers, a “rough unloading” chamber and a “precise” filling chamber; calibration holes 6 "rough"discharge; calibration hole 7 "accurate"discharge; strain gauges 8, 9, 10; assembly line 11; microprocessor control unit 12; a converter 13 of the signals from the sensors 8, 9, 10; block 14 settings of the set dose mass P _s ; block 15 settings the mass of the dose portion P _s / n, where n is the number of parts; block 16 setting the residual mass P _about (n-1) for all parts except the last; a unit 17 for setting the residual mass P _o (n) for the last part; the starter 18 of the feeder 3 load and the starter 19 of the feeder 4 unloading.

 On the graph of loading and unloading (Fig. 8), section 20 depicts the loading process of one of the parts of the dose, except the last; section 21 depicts the process of unloading one of the parts of the dose, except the last; section 22 depicts the process of loading the last part, and section 23 the process of unloading the last part of the dose.

 The method is implemented as follows.

Before starting dosing, the operator enters the values of all the settings into blocks 14 17. After starting the device in operation, block 12 remembers the residual mass P ₀ , which from the strain gauges 8, 9, 10 through the converter 13 enters its input. Since the value of P ₀ due to the dosing error, the buildup of material from cycle to cycle can vary, before loading the first partial dose, the setpoint of the set mass is adjusted, after which the “load” command is generated at the output of control unit 12, which at time t ₀ contactor 18 is supplied to the actuator (not shown feeder 3 loading. feeder 3 is opened and the dispenser 2 starts filling material. The filling is done in the "coarse" and the flow is terminated at time t ₁ to achieve weight batching th material values P _f = P ₀ + P ₃ / n, where P _f actual weight parts of a given dose;. P _o residual weight; P _of a predetermined mass quantity of dosing material; n number of parts.

 In this case, the magnitude of the part of the given dose is equal to the difference between the actual mass and the residual.

, так как из камеры "грубой" выгрузки выгружается материал по массе равный P_к.д., а из точной в K-раз меньше, т.е.

. Этот момент, когда только в камере "точной" досыпки остается материал, является моментом перехода на режим точной досыпки или снижения скорости. Причем переход на пониженную скорость происходит без дополнительного переключения или включения механизма точной досыпки.P ₃ / n P _f P _o
At the end of the load, if there are no emergencies, in block 12 the "Unload" command is generated, which through the starter 19 is fed to the drive (not shown) of the unloading feeder 4. The unloading feeder 4 opens and at time t ₁ the process of unloading the material onto the conveyor 11 begins. Unloading begins immediately through the “rough” unloading hole 6 and the “exact” unloading hole 7. In this case, the unloading occurs intensively (Fig. 2). for some time, the level of material in the dispenser 2 reaches the upper edge of the partition 5 separating the lower part of the weight dispenser 2 into 2 chambers. The mass of the material to be dosed in the fine-filling chamber is denoted by P _cd . Obviously, as shown in Fig. 3, the mass of material in the camera "rough" you load is equal to the mass of material in the chamber “fine filling.” Since the area of the calibration hole 6 “rough” discharge is K times larger than the calibration hole 7 of the “precise” filling, the material from the chamber “rough discharge” is unloaded K-times faster than from the “exact” . This is depicted in figure 4
If you continue the process of unloading, then there comes a moment (Fig.6), when the material remains only in the camera "accurate" unloading. The mass of material in this case in the "exact" discharge chamber

since the material equal to P _{cd is} unloaded from the “rough” discharge _chamber , and from the exact one K-times smaller, i.e.

. This moment, when only material remains in the “fine” filling chamber, is the moment of transition to the regime of precise filling or speed reduction. Moreover, the transition to a reduced speed occurs without additional switching or switching on the mechanism of precise refilling.

When dosing a predetermined dose mass P _{s in} parts P _s / n, where n is the number of parts in order to increase the productivity of the process, it is sufficient not only to load in intensive mode, but also to unload. However, it is obvious that loading and unloading in intensive mode is advisable for all parts except the last. In order to achieve a predetermined dosing accuracy, the loading of the last part is carried out in "rough mode, unloading is carried out first in the" rough "and then in the" exact "mode.

In order to unload all parts except the last one quickly using this method, it is necessary that the predetermined part mass of the dose P _s / n has time to be unloaded before the unloading switches to the “accurate” filling mode. This means that the residual mass (P _о (n-1) of the material for (n-1) doses (i.e., for all doses), except for the last one, should be greater than P _t . P _о (n-1)> P _t , where P _{t is the} mass of the transition to the "exact" discharge mode, or the remainder of the dose.

The moment of the end of the unloading upon reaching the residual mass P _o (n-1)> P _t shown in figure 5. In FIG. 8 this corresponds to time 2.

максимальная погрешность дозатора в процентах при загрузке. Поэтому P_о(n) необходимо задавать не просто меньше P_т, чтобы обеспечить гарантированный переход на "точную" досыпку, а меньше на величину погрешности

.For n 4 (number of parts 4), the second and third partial doses are loaded and unloaded similarly. The loading of the 2nd and 3rd partial dose occurs at time intervals t ₂ -t ₃ and t ₄ -t ₅ , and unloading at time intervals t ₃ -t ₄ and t ₅ -t ₆ . Dosing of the 1st and 2nd, 3rd doses in this case is carried out with the task of setting the residual dose mass P _о (n-1) P _t , which guarantees the unloading of the partial dose in the intensive "rough" mode. When dosing all parts of the dose except the last. Material loading is carried out to the material mass value P _f (n-1) P _about (n-1) + P _s / n (Fig. 8). Download of the last dose (interval t ₆ -t ₇ (in Fig. 8) is carried out from the condition P _f (n) = P _o (n) + P _s / n, where P _o (n) is the residual mass of the material for the last dose Moreover, P _o (n) must be less than P _t to ensure that during unloading the transition to the regime of "accurate" filling. Unloading of the last part of the dose (interval t ₇ -t ₈ in Fig.8) goes through the same stages of unloading shown in Fig. .2 4. After the moment shown in Fig. 4, for the last part of the unloading stage are shown in Figs. 6 and 7. Fig. 6 shows the moment of transition to the regime of precise refilling. time t ₈ -t ₉ carried exact dosypki until reaching residual mass _of P (n). accurate unloading end of the last part shown in Fig. 7. To effect unloading end of the last part in the "exact" mode must fall during unloading of the zone "below "P _t . For this, it should be borne in mind that when loading the last part, as well as when loading the other parts, it may be that P _f (n) may be greater than a given value by an error equal to

maximum dispenser error in percent when loading. Therefore, P _o (n) must be set not just less than P _t to ensure a guaranteed transition to an “accurate” refill, but less by the amount of error

.

This follows from the following expressions. When loading, the actual dose mass P _f / (n) is the sum of the residual mass P _o (h) plus the given mass of the phase part P _s / n.

и составлять величину

В то же время

должно быть равно

, т.е.But the actual mass P _f (n) may be greater by

and make up

In the same time

should be equal

, i.e.

Приравняем

, тогда

.

Equate

then

.

, что гарантирует переход на "точный" режим выгрузки последней части дозы.The expression on the left side actually means the residual mass of the material. That is, when dosing the last part with a loading error, the residual mass must be set from the condition

, which guarantees the transition to the "exact" mode of unloading the last part of the dose.

(n-1) может быть равно

, что гарантирует попадание в зону "выше" P_т.The error when loading all parts except the last can only additionally guarantee the fulfillment of the condition P _о (n-1) P _t , because

(n-1) may be equal

, which guarantees getting into the zone "above" P _t .

 This dosing method allows to increase the productivity of the line due to the fact that all partial doses, except the last, are intensively loaded and intensively unloaded, the last part of the dose is intensively loaded. The unloading of the last dose is carried out first intensively, and then in a frozen mode, which increases the final dosing accuracy.

In addition, in this method, by setting a different residual weight for partial doses without changing the control action on the actuators, it is possible to carry out a different unloading mode with an equally intense load. The presence of residual weight makes it possible to take into account dosing errors committed in all partial doses and to accurately unload the total dose P _s onto the assembly line.

Claims (1)

A method for weight dosing bulk materials, including loading the dose in parts of a mass equal to the quotient of dividing a given dose weight by the number of parts, determining the mass of the unloaded material after unloading each part, calculating the difference between the given dose mass and the total mass of the unloaded material, adjusting the mass of the last part, feeding all parts except the last, in the mode of intensive unloading and unloading of the last part, first in the mode of intensive feeding, and then slowed down, characterized in that the unloading azhdoy partial dose is carried out with a net weight of material, the residual mass setpoint for all parts except the last is set based on the condition _of R> P _t, and the residual mass for setting the last dose is set based on the condition

where P _{about the} residual mass of the material;
P _{t the} remainder of the dose;
P _{c is the} set dose weight;
δ is the maximum loading error;
n is the number of parts.

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