3. 4.

H. Buckle and J. Pollitt, J. Text. Inst., 39, No. 6, 199-210 (1948), V. A. Zinov'ev (editor), A Short Technical Handbook [in Russian], Part i, GITTL, Moscow (1952).

ESTIMATING THE RELIABILITY OF EQUIPMENT BY USING AUTOMATED PROCESS CONTROL

A. K. Nauru.v, V. P. Linnik, UDC 678.4:62-192:65.011.56 V. I. Tishchenko, and V. G. Shevchenko

Efficiency in manufacturing synthetic fibres depends greatly on the level of automation and on work to ensure high reliability of all units in the technological lines. At present, in the pilot plant of the Mogilevskil "Khlmvolokno" Industrial Union, automated process con- trol (APC) is being introduced, in which it is advisable to include a subsystem intended to evaluate the reliability of the technical devices in the unit.

The use of computers to collect and handle information about the reliability of equip- ment is widespread, both here and abroad. To a considerable extent it aids in operational adoption of organizational and technical decisions, and in the end it helps increase manu- facturing efficiency [I, p. 16].

Control of the reliability of the experimental unit at hand presents definite difficul- ties, brought about by the diversity and complexity of the equipment whose use is being mas- tered, the continuity and the multifactor nature of the technological process, and the spe- cial features which ensue in organizing planned repair. Wlth the objective of introducing a system for collecting and treating information on reliability with the aid of a computer, we conducted a complex of preparatory operations in the pilot plant.

The composition of the basic groups of problems which are solvable on the computer was determined. This was, first of all, an estimate of the quantitative reliability indices, whose nomenclature arises from the requirements of specific manufacturing operations and existing methodological indications [2]. Moreover, provision is made for calculations of economic indices in technical servicing; indices connected with the consumption of spare parts; problems in predicting the time and character of shutdowns; and treatment of data for the rapid analysis of problems on means and time for technical servicing and repair, and other calculations.

The structure of reliability control consists of the following interconnected units:

a pilot plant;

a D-3-28 computer which is part of the ACSTP, to which the original information on re- liability of the set-up goes;

specialists and services for manufacturing, who use the calculations performed on the computer to develop organizational and technical indications for the plant on increas- ing the reliability of the installation and scientiflc-methodological recommendations on improving methods of using the computer and statistical data on the operation of equip- ment.

It has been decided to evaluate the reliability of equipment by several quantitative characteristics. The set of these affords a more complete and objective estimate of the re- liability of the object under study. In conformity with existing rules and requirements, as the basic reliability indices of the experimental unit in the initial stage of observations we determined the following: operation to failure; mean restoration time, probability of failure-free operation; and coefficient of technical utilization.

We determined also the composition of the subcontrol elements of the object (or system), including those positions which affect in larger degree the volume and quality of the final product. These elements were combined with respect to technological criteria into seven func- tional units (subsystems): preparation of raw material, esterlfication, preliminary poly- condensation, polycondensation, spinning sections, Dinil boiler, and controlling complex.

Translated from Khimicheskie Volokna, No. i, pp. 49-50, January-February, 1983. Origi- nal article submitted June 19, 1982.

70 0015-0541/83/1501-0070507.50 © 1983 Plenum Publishing Corporation

TABLE I

Failure record

I

2

3

4

5

6

7

8

9

I0

11

12

13

14

15

16

17

I Untt

[Date of failure (year, month, day) 1 " I

.To current month (h) Operation from start of observations to failure

Downtime (h, mln)

, Current month (h)

Day-calendar time (h, mln)

Expected time

Restoration time

Total downtime

For finding source of 1rouble

~or eliminating problem

I 1 I,

Unit

Device (position)

Part

Spare part consumption

Total restoration time

Description of failure Suggested reason (in detail, with use of back side of blank)

Nature of repairs

Repair labor involved (man-houm)

Reported by: C~ecked by: Coder

I I

The adoptedperiodicity in calculating reliability indices for various elements and sub- systems includes lifetimes to replacement up to several years; moreover, calculations on requirements, which are necessary for rapid analysis of operational factors, are provided for.

A "failure card index" has been developed and is used to collect information on failure as applicable to the experimental unit.

To evaluate the selected reliability indices using a computer [3], we determined the composition of the information masses and codifiers, gave their descriptions and the proce- dure for developing them, and developed algorithms for determining quantitative reliability characteristics [4, p. 342]. Sincethe scopeof solvable problems on estimation operational indices will be constantly enlarged, recommendations are given on setting up additional prob- lems and the sequence of introducing them.

Information collected over four years from the usual calculational documentation on failure was treated by engineering methods, Thus, it turned out that the least reliable sub- systems of the unit are "raw material preparation" and "polycondensation," to which about 60% of the total number of failures are assignable. We also discovered the least reliable ele- ments of the unit. It was found that operation to failure obeys an exponential distribution law.

Experience in operating equipment in a number of branches of the industry has shown the advisability of organizing a reliability service in pilot plant production [i]. In this con- nection, methodological bases of organizing the reliability service (general positions, basic problems and responsibilities, priorities, and structure) [5, p. 31] have been worked out as applicable to the experimental unit.

The creation of a reliability service within the framework of experimental manufacturing will make it possible to determine the comparative characteristics of operational reliability

71

of existing technologi:cal assemblies and of the local control system, on one hand, and of the same technological units of introduction of APC based on microprocess technology with con- sideration of the changes introduced into the proJect and into the control system, on the other hand. The transition to a qualitativelynew level of automationof the technological process compels one to set up anew and solve the problem of operational reliability of the experimental unit, the more so since experience in automatic control of a technological process and reliabil- ity can be used successfully in developing principles for devising control systems for promis- ing multiton manufacturing operations.

LITERATURE CITED

i. Experience in Reliability Service Operation in Scientlfic-Research Institutes, Design and Construction Plants, and Industrial Plants [in Russian], Znanie, Moscow (1975).

2. Procedure in Selecting the Nomenclature of Normalizing Indices for the Reliability of Technical Devices, MU-3-69, Standarty, Moscow (1970).

3. Procedure for the Statistical Treatment of Information on the Reliability of Technical Articles on a Computer [in Russian], Standarty, Moscow (1974).

4. A.A. Modin, E. G. Yakovenko, and E. P. Pogrebnol, Handbook for the Developer of Auto- matic Control Systems [in Russian], ~konomika, Moscow (1978).

5. Type Positions on Reliability Subdivisions in Organizations and in Plants of Industry (Recommended) [in Russian], RDTP 47-57, Standarty, Moscow (1976).

72