RU2788300C1 - Method for determining the number of inappropriate products in the sample - Google Patents

Abstract

FIELD: testing equipment.

SUBSTANCE: invention relates to methods for non-destructive testing of a sample or batch of products. According to the method, a product mismatch criterion is set, according to which, when one of the two different values of the controlled parameter P1, P2, P1>P2 is reached, the product is recognized as appropriate, and not when the other is reached, the sample size N is also set. At the same time, a sample with a given value P₀ of the controlled parameter is connected to each sample product in parallel to the outputs by which the parameter is controlled with P₀>NP₂, P₁>NP₀, the samples are connected in series. All products of the select with samples are controlled simultaneously, the total value P_c of the controlled parameter is determined for them, and the number of m inappropriate products in the sample is determined by the formula.

EFFECT: select control time is reduced, the complexity of its control is reduced.

1 cl, 1 dwg

Description

The invention relates to methods for non-destructive testing of a sample or batch of products.

A known method for controlling a batch of products (Vorontsov L.N., Kondorf S.F., Truten V.A., Fedotov A.V. Theory and design of control machines. - M .: Higher school, 1980, p. 296), consisting in the fact that when the cycle of operation of the control automatic system is greater than the cycle of operation of the automatic line, but a multiple of it, several products are simultaneously controlled by increasing the number of streams. This method of directing products into streams for parallel control allows to reduce the time of control of a batch of products.

The disadvantage of this method is the longer batch control time, since the products in each strand are controlled individually. In addition, it is necessary to use several controls in an amount equal to the number of streams.

A known method of statistical control of a batch of products (GOST R 50779.52-95. Statistical methods. Acceptance quality control by alternative attribute), which consists in the fact that for a given batch size and criteria for non-conformity of products, a standard level of non-conformities is set, the sample size, products are selected from the batch. Complete control of selected products is carried out, the number of nonconforming products in the sample is counted, the actual level of nonconformity is determined, and it is compared with the standard level. If the actual level of inconsistencies in the batch does not exceed the established normative level, then the batch is recognized as suitable, otherwise the batch is rejected.

The disadvantage of this method is the long time of control of a sample of products, since it is necessary to control all products individually in order to find non-conforming products, and the control time for a sample of products is equal to the sum of the control times for each product of this sample. The control of products of the entire sample is also very laborious.

The technical problem to be solved is to reduce the time for determining the number of nonconforming sample products by one control tool.

The solution of the problem is achieved by setting the criterion of product nonconformity, according to which, when one of the two different values of the controlled parameter P1, P2, P1> P2 is reached, the product is recognized as conforming, and when the other is reached, no, the sample size is N, the parameters of the selected products are controlled , determine the number m of nonconforming products in the sample, in addition, to each sample product in parallel with the outputs that control the parameter, connect a sample with a given value P ₀ of the controlled parameter, and P ₀ >NP ₂ , P ₁ >NP ₀ , the samples are connected in series , simultaneously control all items in the sample with samples, determine for them the total value P _{c of} the controlled parameter, and the number m of nonconforming items in the sample is determined by the formula

where [...] is the nearest integer,

if the achievement of the value of the parameter P ₂ indicates a non-compliance of the product with the requirement, otherwise

The method can be applied under the following conditions. The control is non-destructive. There is one control for this parameter. The inspection cycle time of any part of a sample of products is equal to (close to) the inspection cycle time of one product.

A non-compliance with the requirement is considered to be the presence of a product parameter in one of two possible states P ₁ and P ₂ , P ₁ > P ₂ (a binary state of the product, characterized by two different values of the controlled parameter).

For example, control of an electromagnetic relay of a contact type: a product is considered suitable if, when power is applied to the contacts of the winding of an electromagnet, when a given current flows through them, the contacts of the controlled circuit will actuate (for example, close). Otherwise, the relay is rejected. Another example is the control of fuses, in this case the products are controlled without additional influence.

The method is implemented as follows. It is required to give a conclusion on the suitability of a batch of valve-type electromagnetic contact relays with make contacts according to a sample of volume N with a given rejection number K. Products are considered suitable (corresponding) for actuation if the relay contacts actuate when the current flowing through the windings of the control coils does not exceed the specified I _t . For definiteness, we assume that when triggered, the contacts close.

When the relay contacts are open, the resistance between them is R, and when closed, r, R> r (in this case, P ₁ = R, P ₂ = r).

The method is implemented using the device, the block diagram of which is shown in Fig.1.

The device contains the first regulated DC power supply 1, the panel 2, the second regulated DC power supply 3, the voltage meter 4.

The panel contains N sections 5 ₁ ... 5 _N with connectors for installing products (not shown) and terminals 6.7. Each section 5 _j (j = 1, 2…N) contains the first 8 _j terminal, the second 9j terminal and a resistor 10 _j connected to them with a given resistance value R _j . Connector contacts are connected to terminals 8 _j , 9 _j , respectively, into which the outputs of the relay contacts are installed. Controlled relays 11 ₁ ... 11 _N are installed in the section connectors.

Terminal 7 is connected to the connector contact of the first section 5 ₁ , into which the first output of the control coil of the relay 11 ₁ is installed. Terminal 6 is connected to the connector contact of the last section 5n, in which the second output of the control coil of the relay 1 11 _N is installed. The first output of the first power supply 1 is connected to terminal 6, and the second output is connected to terminal 7.

The terminals of the connectors, in which the contacts of the control coils of the relays of neighboring sections are installed, are connected in series.

The first output of the second power source 3 is connected to the first terminal 8 _{1 of} the first section 5 ₁ , and the second to the second terminal 9 _N of the last section 5 _N .

Resistors 10 _j of sections 5 ₁ ,…5 _N have a given equal resistance and are connected in series

The device works as follows. In the initial state, power is not supplied to terminals 6.7 and 8 ₁ , 9 _N. According to a predetermined volume, N relays are sampled, installed in the sockets of the panel 2 (figure 1). In this case, the control coils of all relays will be connected in series.

The current I ₁ at which the relay should operate, the current I ₂ at which the relay should release and the current I _k at which the resistance of the relay contacts is measured, is specified in the regulatory documentation for the relay.

Terminals 6 and 7 are energized by the control coil circuit from the first DC source 1. Since the control coils are connected in series, the amount of current in them is the same. By adjusting the first power supply 1, the current I ₁ is set through the relay coils. After setting the current I ₁ by adjusting the second power source 3, set the current I _k in the circuit between terminals 8 ₁ section 5 ₁ and 9 _N section 5 _N . Then, the voltage meter 4 measures the voltage drop between these terminals. The result of measuring the voltage and current I _k determine the resistance of the circuit between terminals 8 ₁ section 5 ₁ and 9 _N section 5 _N .

После окончания цикла контроля устройство приводят в исходное состояние.

After the end of the control cycle, the device is brought to its original state.

If out of N relays m did not work, then the resistance of the circuit will be

(in this case R _c =R _c ).

From here, the number of nonconforming products is determined by the formula

where […] is the nearest integer.

we get

For the case of relay control for release, when relays are considered suitable, if the release of contacts occurs at a current of at least I ₂ , reduce the current through the control coils of the relay to I ₂ and measure the resistance of the circuit according to the above.

In this case, we similarly obtain

When conditions (6), (7) are satisfied, we obtain

Let's consider a specific example. Control of the batch of relays by sample size N=20. The marriage number is equal to K=2. Relays are considered to meet the requirement if, when a current of no more than I ₁ flows through the control coil, the contacts close. The relay resistance R with open contacts can be considered infinite, the nominal value of the resistance of closed contacts r=0.1 Ohm. We set the resistance of the sample R ₀ =100 Ohm, while the spread of the parameter r can be neglected.

All N relays are installed in the panel sockets and perform the above operations.

Let the circuit resistance R _c \u003d 201.8 ohms. Then, since conditions (6), (7) are satisfied, according to (8) we obtain the number of nonconforming items in the sample

Since m=K, the batch should be rejected.

The method allows you to simultaneously control all products of a sample or batch using only one measuring tool. To determine the number of nonconforming products in the sample, one control cycle is sufficient, which is much less than in the case of analogues.

The method allows to significantly reduce the time of control of a sample or batch and reduce the complexity of control.

Claims (9)

A method for determining the number of nonconforming products in a sample, which consists in setting a product nonconformity criterion, according to which, when one of the two different values of the controlled parameter P1, P2, P1>P2 is reached, the product is recognized as conforming, and when the other is reached, no, the volume is set samples N, control the parameters of the selected products, determine the number m of non-conforming products in the sample, characterized in that to each sample product in parallel with the outputs that control the parameter, connect a sample with a given value P ₀ of the controlled parameter, and P ₀ >NP ₂ , P ₁ >NP ₀ , the samples are connected in series, all the products of the sample with the samples are controlled simultaneously, the total value P _from the controlled parameter is determined for them, and the number m of non-conforming products in the sample is determined by the formula m = [(P _c /P ₀ -NP ₂ /(P ₂ +P ₀ ))/(P ₁ /(P ₁ +P ₀ )-P ₂ /(P ₂ +P ₀ ))], where […] is the nearest integer, at P ₁ >> P ₀ and R ₀ >> R ₂ m = [(P _c -NP ₂ )/P ₀ ], if the achievement of the value of the parameter P ₂ indicates a non-compliance of the product with the requirement, otherwise m = [(NP ₁ /(P ₁ +P ₀ )-P _c /P ₀ ))/(P ₁ /(P ₁ +P ₀ )-P ₂ /(P ₂ +P ₀ ))], at P ₁ >> R ₀ and R ₀ >> R ₂ m = [NP _c /P ₀ ].

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