METAL-WORKING INDUSTRY — the industry, the enterprises a cut make the mechanical equipment and hardware of different function.
The technology applied at the enterprises of L. S. despite the big range of products, on a gigabyte. to requirements differs from technology in forge and press, heat-treatment, galvanic, mechanical shops of the enterprises a little mechanical engineering industry (see). Distinctiveness of technology of the enterprises of L. S. is the large volume of abrasive metal working (a point, grinding, polishing).
Grinding (abrasive operational development) — the process of superfast cutting which is carried out by the abrasive tool consisting of grains natural (a sandpaper, corundum, flint) or artificial (electrocorundum, silicon carbide, boron carbide, synthetic diamonds, etc.) the abrasive materials fastened with a special sheaf (ceramic, silicate, etc.). Important property of the abrasive tool is its granularity, i.e. the size of abrasive grains in the 100-th shares of millimeter designated by numbers according to GOST 3647 — 71. Grinding is made on universal and special machines with manual or mechanical feed of a job to the abrasive tool. Final operation is polishing, the Crimea is provided smoothness and smooth surface of the processed surface. Grinding is followed by dust formation, intensity to-rogo at different stages tekhnol, process is not identical and depends on the sizes of a job, structure and properties of the abrasive tool. The Maximum Allowable Concentration (MAC) of content of grinding dust in air of production rooms of 6 mg/m 3 .
Dust content of air during the use of natural abrasives is much higher, than at use artificial since natural abrasive materials in comparison with artificial are spent for unit of the processed surface more. The chemical structure of natural abrasives defines also higher percentage of free silicon dioxide at their use.
The more scales, than agnails and sinks on a job, the renting of metal, an expense of an abrasive is rather more and dust content of air is higher.
At rotation of the abrasive tool counterclockwise the dust torch passes through a zone of breath of the worker, creating with other things being equal higher concentration, than at rotation to the opposite side. Dust content of air during the operation of machines with moistening though below, than at dry processing, however quite often exceeds maximum allowable concentration. It is explained by bad wettability of grinding dust.
Concentration dust (see) in air depend on efficiency of vent systems. Grinding dust — the typical representative of the mixed aerosols of disintegration; it is the high-disperse aerosol which is deeply getting into respiratory tracts (see. Aerosols ).
Work of the worker at abrasive processing on machines with manual feed of a product to the tool demands considerable static muscular stress. The main loading is the share of muscles of a brush and a forearm. Vibration (cm), edges is transferred to hands of the worker, characterized by a wide range of frequencies. More high levels of vibrospeed are observed during the grinding works. Emergence of vibration is caused generally by disbalance of the rotating masses in the machine, technical condition of the machine, its vibrostability.
In a range noise (see) averages and high frequencies (1500 — 8000 Hz) prevail. The major factors leading to change of intensity of noise are: technical condition of machines, a type of the used circle, the acoustic characteristic of production rooms.
Incidence of workers in L. S. with temporary disability both on level, and on character differs from incidence of workers of mechanical engineering industry a little. From occupational diseases are possible pneumoconiosis (see), vibration disease (see).
Actions for improvement of working conditions consist in fight against dust content, noise and vibration. It is reasonable to place workshops of abrasive processing in the isolated rooms.
Dust content of air can reduce improvement of quality of preparations by improvement of kuznechnoshtampovochny processing, a right choice of abrasive material taking into account not only tekhnol., but also dignity. - a gigabyte. requirements and use of local ventilating devices (see. Ventilation ).
During the development of constructive solutions of the local exhaust ventilation it is necessary to consider features of technology, the sizes, a configuration of a job; to combine no more than 10 — 12 local suctions in each vent system; to determine optimum volumes of the deleted air by each local suction.
Decrease in levels of vibration and noise is reached by replacement of type-setting circles with monolithic elastic circles, careful balancing of circles, use of machines with the raised degree of vibrostability, use of vibroprotective handles on the products given manually to the abrasive tool; the device of the flexible inserts separating the machine from the pipelines attached to it and the elastoviscous laying mounted in joints of air ducts; facing of ceilings and walls sound-absorbing materials.
The important direction in the organization of the rational mode of work of grinders is creation of integrated teams with interchangeability of professions at alternation of works.
For injury prevention it is necessary to respect strictly the rules of admissible district speed, the rule of storage and strength test of the abrasive tool; to equip grinders with protection covers. Workers of grinding workshops shall be exposed preliminary (at revenues to work) and to periodic medical examinations. Persons under 18 are not allowed to works on abrasive metal working; grinders are granted additional leave for 12 working days.
Use of a complex of the listed actions promotes improvement of working conditions and decrease in incidence of the working enterprises of L. S.
Bibliography: Questions of occupational health and professional pathology of workers-grinders, under the editorship of S. I. Ashbel, Gorky, 1973, bibliogr.; M and to v of l and N with to and y A. M. and E p and sh and N of A. B. Occupational health at abrasive processing of metal products, the Gigabyte. work and the prof. having got sick., No. 12, page 1, 1974, bibliogr.; Stanislavsky Ya. M. of ides of river. A pneumoconiosis at workers of mechanical engineering industry, page 14, Kiev, 1970; Hukhrina E. V. and Tkachyov B. B. Pneumoconiosis and their prevention, page 323, M., 1968; F about and V. La pneumoconiosi clei pulitori di oggetti metallici, Med. d. Lavoro, y. 58, p. 588, 1967; Rabenda A. i Gluszczak S. Warunki mikro-klimatyczne i wibracja miejscowa na sta-nowiskach pracy szlifierzy, Ochrona Pra-cy, No. 3, s. 20, 1976.
And. B. Epishin.