To a technique of performance of measurements at metrological examination

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TO A TECHNIQUE OF PERFORMANCE OF MEASUREMENTS AT METROLOGICAL EXAMINATION

Savin Igor Alekseevich1, Chemborisov Nail Anvarovich2

1Kazan National Research Technical University named after A.N.Tupolev, PhD technical sciences, associate professor, Head of Department

2Southern Ural State National Research University, Miass branch, Dr.Sci.Tech., professor

Abstract

metrological examination measuring result

Metrological examination of a technique of performance of measurements is understood as the analysis and an assessment of a choice of methods and measuring instruments, operations and rules of carrying out measurements and processing of their results. The examination purpose - establishment of compliance of a technique to the imposed metrological requirements. Without carrying out this examination release of products of mechanical engineering of appropriate quality is impossible.

Keywords: drawing, measurement, metrological examination, normative document

Requirements to development, certification and standardization of the technique of performance of measurements (TPM) are regulated by GOST P 8.563-96 “GSI. Techniques of performance of measurements”; in the same place requirements to metrological examination are established.

Projects of state standards in which there are TPM intended for application in spheres of distribution of the state metrological control and supervision have to be exposed to metrological examination in the state scientific and metrological centers Rostechregulation.

Documents on MVI which aren't used in spheres of distribution of the state metrological control and supervision subject to metrological examination in the order established in branch or at the enterprise.

It is expedient to carry out metrological expertize of materials on development of TPM in the following sequence, to check:

- completeness of the documents submitted for metrological examination; thus can be included in the package of documents:

* initial requirements (specification) on development of TPM;

* the document (draft document) on TPM;

* programs and results of experimental or settlement estimation of characteristics of an error of measurements;

* the report on results of research at a development stage or approbations of TPM;

* other documents of development and research MVI (for example, the software when using computer facilities).

Analyze sufficiency and completeness of the basic data necessary for development of TPM and for estimation of characteristics of errors of measurements which will be attributed by TPM. Basic data are provided in GOST P 8.563-96, including:

- purpose of TPM (a scope, the name of the measured size, limits of measurements, characteristics of the measured size, characteristics of object of measurements if they can influence an error of measurements, etc.);

- requirements to an error of measurements; In the absence of requirements in an explicit form they should be established, proceeding from requirements to reliability of control or an error of tests. Often in practice use a ratio between blundered measurements and tolerance zone border;

- conditions of measurements (temperature, humidity, pressure, other factors of influence). Conditions of measurements can be set in the form of nominal rates and (or) borders of ranges of possible values of the influencing sizes;

- requirements to automation of measuring procedures;

- requirements to safety of performance of work;

- other requirements according to specifics of TPM.

Analyze standard documentation on which references in materials to TPM are given, check, whether expired the term of their action, reveal not specified normative documents.

Check correctness of metrological terminology (according to RMG 29-99 and other standards establishing terms and definitions in concrete areas of measurements) and correctness of names and designations of sizes and their units (according to requirements of GOST 8. 417-2003).

Estimate correctness of a choice of measuring instruments and a choice (development) of a method of measurements. In a number of technical documentation recommendations about application of concrete measuring instruments are provided. Analyze completeness of the accounting of all factors influencing an error of performance of measurements; estimate validity of the assumptions accepted when developing TPM.

Analyze and estimate completeness of identification and the accounting of components of an error of measurements (typical sources and the making errors of measurements are given in appendix A by GOST P 8.563-96).

Analyze a choice of a way of estimation of characteristics of the making errors and a way of their summation. At research use the following procedures of estimation of errors of measurements: settlement, experimental or settlement and experimental. Analyze and estimate completeness and validity of procedure of preparation and performance of measurements.

Establish expediency and possibility of increase of accuracy of measurements on the analyzed TPM.

Establish possibility of control of accuracy of measurements and analyze procedure of such control.

At metrological examination of the documents regulating TPM it is necessary:

- to establish, whether this TPM belongs to spheres of distribution of GMN (Art. 13 of the Act of the Russian Federation “About ensuring unity of measurements” the version of 1993);

- to establish compliance of a technique of performance of measurements to requirements of GOST P 8.563-96.

Thus it is analyzed:

* name TPM correctness;

* existence of all necessary sections and correctness of their name;

* completeness and correctness of a statement of all sections.

- to establish existence (or absence) numerical characteristics of errors of measurements;

- to estimate validity of the attributed characteristics of an error of measurements;

- to check implementation of requirements regarding conditions of measurements;

- to establish observance of the requirements to measuring instruments used when performing measurements;

- to estimate validity and correctness of a choice of measuring instruments on accuracy;

- to check completeness and correctness of a statement of requirements to auxiliary devices, standard samples, the certified mixes, reactants;

- to check completeness and correctness of a statement of algorithm of preparation and performance of measurements;

- to estimate possibility of control of accuracy of results of the measurements received when using this TPM;

- to check completeness and correctness of a statement of requirements for safety measures and environmental protection;

- to check compliance of the applied terms and designations of sizes and their units to requirements of standard documentation.

The purpose of metrological examination of drawings is verification of the necessary means and data sufficient for control of the sizes, maximum deviations, etc. parameters and requirements, and also an assessment of their suitability for control.

Metrological examination is recommended to subject assembly, assembly, outline drawings, and also drawings of separate details.

It is expedient to carry out metrological expertize of the drawing of a detail in the following sequence:

- in the presence on the drawing of text records of norms of accuracy check correctness of terminology. At detection of terminological mistakes it is necessary to understand the valid sense of qualifying standards. In some cases carrying out metrological examination before receiving the corresponding explanations from the developer is inexpedient;

- reveal the sizes limited to admissions, establish need and possibility of their control;

- check mutual coordination of admissions of the sizes, forms and arrangements;

- estimate mutual coordination of admissions and requirements to a surface roughness;

- check possibility of control of admissions of a form and a relative positioning of surfaces.

It is necessary to distinguish metrological examination and metrological control. In control, generally check correctness of metrological terms, names and designations of physical quantities and their units.

Metrological examination comes to an end with recommendations about improvement of metrological providing. Considering that each documentation has a developer (the owner of documentation), it responsible for results of introduction of the project, he has the right to adopt or not to accept suggestions for improvement of metrological providing by results of metrological examination. Therefore, proposals of experts in metrological examination have advisory nature. As for remarks by results of metrological control, entering into drawings of the corresponding adjustments is obligatory, since this elimination of the made mistakes.

Now the domestic enterprises are developed actively and introduced quality management system. Metrological examination in our country was created for increase of a level of quality of production. Modern approach to quality sets a task not of control, and ensuring quality and not only production, it is solved the new concept - TQM (the general management by criteria of quality). Besides, firms, in addition to the created systems of quality management, develop specialized methodologies of improvement and ensuring quality. In these conditions metrological examination, it is possible to tell, receives a second wind and gets new functions and opportunities. Only creative approach to further improvement of metrological examination is capable to bring new decisions on additional improvement of quality of production of the enterprises of machine-building branch.

References

1. ГОСТ Р 8.563-96 «ГСИ. Методики выполнения измерений»

2. РМГ 29-99

3. ГОСТ 8. 417-2003

4. ст. 13 Закона РФ «Об обеспечении единства измерений»

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