RU2257552C2 - Mode of definition of quantity of articles of the same type by way of weighting - Google Patents

Abstract

FIELD: the invention refers to weight measuring technique.

SUBSTANCE: it may be used for definition of quantity of articles of the same type by way of weighting. The mode is in definition over and over again of an average mass of the articles of the same type at measuring mass of different number of articles. After measuring of the articles of the whole lot a desired quantity of articles in the lot is received with the aid of verified meaning of an average mass. At that an assured tolerance is got in the limits of which the quantity may be changed.

EFFECT: the invention increases accuracy and reduces labor-intensiveness of counting of the articles of the same type.

Description

The invention relates to a weighing technique and can be used to determine the number of similar products by weighing.

There is a method of determining the number of products of the same type by weighing, which consists in placing several products on an auxiliary scale, measuring their weight, determining the average weight of one product by dividing the measured weight by the number of stacked products, laying the entire batch of products on the main scales, measuring the weight of the products in batch and determine the desired number of products in the batch by dividing the batch mass by the average mass of one product, followed by rounding to the nearest whole number (Patent No.RU 2058018 C1, CL G 01 G 19/42, 1996). By introducing auxiliary weights, a more accurate determination of the average weight of one product, and hence the desired number of products in a batch, is provided. But this method does not have universality, since for standard scales having one platform, it does not allow to introduce a special counting mode of operation.

A known method of weighing products with rounding the weighing result to an integer number of discrete d, which consists in placing the product on the scales, measuring the initial value of its mass, adding weights of the same mass, smaller than the discrete, for example, 1/10 d or 1/5 d, determine the mass of added weights, at which the reading increases by 1 d, and the final weight of the product is selected in the interval taking into account the mass of added weights before and after the discrete change (OIML INTERNATIONAL RECOMMENDATION R 76-2, p.10). The method allows to increase the sensitivity of measurements, but it is not applicable to the task of determining the number of similar products by weighing.

There is also a method of determining the number of products of the same type by weighing, which consists in manually counting a number of products, laying them on the scales, measuring their weight with rounding the weighing result to an integer number of discrete d, determining the average weight of one product by dividing the measured weight by the number of products put on the same scales the entire batch of products, measure the mass of the batch and determine the desired number of products in the batch by dividing the mass of the batch by the average weight of one product with subsequent rounding iem to an integer (O.G.Lisin error in determining the number of parts by means of counting scale // Measuring equipment -.. 1998. №3, s.15-18).

This method is selected as a prototype of the invention as the closest to it in technical essence and the achieved result. The disadvantage of the prototype is the low accuracy of counting products in a batch due to the fact that the average mass of one product is determined with a large error by a single independent measurement, the repetition of which would lead to the same result; the method does not allow to estimate the tolerance on the obtained number of products in a batch, which is caused by rounding when discretizing the mass values. In addition, for light products, the mass of which is not large in comparison with the discreteness d, it is necessary to increase the number of products in determining the average mass, and their manual counting is characterized by great complexity.

In the proposed method for determining the number of products of the same type by weighing, the role of the additional weights used in the analogue described above, the method of weighing products, is performed by the products themselves. Instead of a single measurement when determining the average weight, it is suggested that weighing be performed by adding one product to the balance and recording the weight after each addition. The average mass value is determined taking into account all measurements. An increase in the number of independent measurements improves the accuracy of the calculation and reduces the complexity of the method.

The proposed method consists in manually counting a number of products, stacking them on a scale, measuring their weight with rounding the weighing result to an integer number of discrete d, determining the average weight of one product by dividing the measured mass by the number of products, laying the whole batch on the same scales products, measure the mass of the batch and determine the desired number of products in the batch by dividing the mass of the batch by the average mass of one product, followed by rounding to the nearest whole number.

Additionally, when determining the average weight of one product, weighing is carried out repeatedly, adding one product to the scales, starting from one to a given number of pieces. According to the result of each weighing, taking into account the tolerance for rounding, the minimum possible value of the average mass is determined by dividing the measured mass, reduced by half a discrete, by the number of products; similarly, according to the result of each weighing, the maximum possible value of the average weight is determined by dividing the tolerance for rounding by dividing the measured mass, increased by half a discrete, by the number of products. Then, among all the minimum possible values, the maximum is selected, and among all the maximum possible values, the minimum is selected. The true value of the average mass should be between the found maximum and minimum. The desired number of products N in the batch is determined in the range of values obtained by dividing the mass of the batch M by the maximum and minimum values of the average weight of one product. It must satisfy the inequalities:

where m _i is the mass i of the pieces of products that was measured at the stage of determining the average mass of one product, and the maximum and minimum functions of the values in parentheses are for all values of i from 1 to a given number n.

To confirm the feasibility of the proposed method, you should consider an example of its use. Let the weighing be performed on a balance with a discrete reading of 1 g, and the margin of error is ± 0.5 g, so that the readings of the weighing result are guaranteed up to the last digit. Let the unknown average weight of one product in fact have an exact value of 2.2 g. According to the prototype method, 3 products are selected during the first weighing. Their exact mass will be 6.6 g, i.e. the scale will show a rounded value of 7 ± 0.5 g. This means that in the prototype limits are guaranteed for the average weight and one product

. По предлагаемому способу выполняется серия из 3 измерений, в которых взвешиваются грузы с точной массой 2,2; 4,4 и 6,6 г. Округленные показания будут 2, 4 и 7 г. Отсюда для каждого показания получаются оценки средней массы:or

. According to the proposed method, a series of 3 measurements is performed in which goods with an exact mass of 2.2 are weighed; 4.4 and 6.6 g. Rounded indications will be 2, 4 and 7 g. From here, for each indication, estimates of the average weight are obtained:

or

(это число есть максимум), а из 3-го - больше

(это число есть минимум). В результате обе оценки дают конечную неопределенность в значении средней массы, равную

, тогда как по способу-прототипу эта неопределенность есть

, т.е. в 4 раза больше. Соответственно для искомого количества изделий в партии относительная погрешность, связанная с определением средней массы, оказывается в предлагаемом способе в 4 раза меньше, чем в прототипе.It is necessary to consider each of these estimates together with others. So, from the 2nd dimension we get that the average mass should be less

(this number is the maximum), and from the 3rd - more

(this number is a minimum). As a result, both estimates give a final uncertainty in the average mass value equal to

, whereas in the prototype method this uncertainty is

, i.e. 4 times more. Accordingly, for the desired number of products in the batch, the relative error associated with the determination of the average weight is in the proposed method 4 times less than in the prototype.

The same example allows a different interpretation. Let the goal be not to increase accuracy, but to reduce labor intensity. Then you need to determine how much in the prototype method you need to take products when determining the average weight in order to achieve the same accuracy as in the proposed method, i.e. 1/12. The answer is 12 pieces. Indeed, the exact mass value of this quantity is 12 u = 26.4 g. The balance will show a value of 26 ± 0.5 g. This means that in the prototype limits are guaranteed for the average weight and one product

. Иначе говоря, оба способа дают одну и ту же погрешность, но по предлагаемому способу количество изделий при определении средней массы оказывается можно брать в 12/3=4 раза меньше. В результате получают соответствующее сокращение трудоемкости.or

. In other words, both methods give the same error, but according to the proposed method, the number of products in determining the average mass can be taken 12/3 = 4 times less. The result is a corresponding reduction in labor intensity.

The above two examples characterize the limiting estimates of the effectiveness of the method. A compromise solution is also possible when the number of products is taken greater than 3, but less than 12. At the same time, the complexity is reduced by less than 4 times, but at the same time, the accuracy of estimating the average weight also increases, although it is less than 4 times.

Claims (1)

The method of determining the number of products of the same type by weighing, which consists in manually counting a number of products, stacking them on a scale, measuring their weight with rounding the weighing result to an integer number of discrete d, determining the average weight of one product by dividing the measured mass by the number of products, laying on the same scales, the entire batch of products, measure the mass of the batch and determine the desired number of products in the batch by dividing the mass of the batch by the average mass of one product, followed by rounding to the nearest hour isla, characterized in that, in order to increase the accuracy and reduce the complexity, when determining the average weight of one product, weighing is carried out repeatedly, adding one product to the balance, starting from one to a given number of pieces, and the average weight of one product is determined first at each of multiple weighings taking into account the tolerance for rounding for the minimum possible values by dividing the measured mass, reduced by half a discrete, by the number of products and for the maximum possible values by dividing the measured mass calculated by half-discrete, by the number of products, and the final average weight is determined in the range from the maximum among all the minimum possible values to the minimum among all the maximum possible values, the minimum is chosen, while determining the desired number of products in the batch, the tolerance for this quantity is also determined after dividing the batch mass by the maximum and minimum final values of the average weight of one product.