Equipment for protecting against harmful emissions (noise, light radiation, and aerosols) within allowable concentrations for program-controlled semi-automatic machines for thermal cutting of metals

Engineering industries apply high-performance (0.2 ... 20 m/min) plasma arc cutting of metals within the thickness range from 1 to 100 mm with a positioning accuracy of the instrument (plasma torch) of 0.25 mm for blanking operations. This procedure is most suitable for cutting corrosion-resistant metals with a heavy percentage of alloying elements, as well as titanium alloys, and non-ferrous metals. Currently, there is no alternative technology with comparable technical and economic parameters to water-jet, laser, oxygen-fluxing, supersonic thermosetting, and other processing techniques in the metal-working industry. All cutting processes are accompanied by a variety of harmful emissions. The paper deals with the most pressing environmental problems of plasma treatment such as background noise, light emission, release of aerosols, and melt ejection, which adversely affect creative activity, labor productivity, and, in general, vital activity of plant operators and other personnel in the working area. A design of the device protecting from harmful emissions that will be installed on semi-automatic thermal cutting machines is proposed. A model of the gas-hydrodynamic plasma torch-metal path as a source of harmful emissions is developed. The circuit analysis of this model made it possible to design and fabricate an independent protective device to be mounted on semi-automatic thermal cutting machines both in service and newly designed. The implementation of the device resulted in reducing harmful emissions compared to maximum allowable concentrations established by sanitary regulations. This device can be recommended for application in water-jet etching, where the level of sound pressure and gas and dust emissions is significantly higher than in plasma processing. In this case, the main machine does not require any modifications.

References

[1] Aviatsionnaia akustika [Aviation acoustics]. Ed.Munin A.G., Kvitko E.E. Moscow, Mashinostroenie publ., 1973. 448 p.

[2] Sidel’nikov T.Kh. Avtokolebatel’noe shumoobrazovanie pri istechenii gazovykh strui [Self-oscillatory noise level at the end of the gas jets]. Moscow, Nauka publ., 1971. 230 p.

[3] Osnovy prikladnoi aerogazodinamiki. Kn. 2. Obtekanie tel viazkoi zhidkost’iu [Fundamentals of Applied aerogasdynamics. Book 2. Viscous fluid flow over bodies]. Ed. Krasnov N.F.Moscow, Vysshaia shkola publ., 1991. 358 p.

[4] Spravochnik po kontrol iu promyshlennykh shumov [Handbook of industrial noise control]. Ed. Kliuchev V.V., Moscow, Mashinostroenie publ., 1976. 447 p.

[5] Youjun Zhn. Anallysis of Flow Field and Noise Radiated from Axial Fan. International Congress on Acoustics. 2008. 837 p.

[6] Sum K.S., Pan J. Effects of the inclination of a rigid wall on the free vibration characteristics of acoustic modes in a trapezoidal cavity. Journal of the Acoustical Society of America, 2006, vol. 119, issue 4, pp. 2201–2210.

[7] Schmidt W. Delphinluftschiff mit Wellantrieb — Wirkung elastischer Wellerbl?tter. Technisch-?konomische Informationen der zivilen Luftfahrt, 1974, vol. 10, no. 4, pp. 240–242.

[8] Kanev N. Sound decay in a rectangular room with specular and diffuse reflecting surfaces. Proceedings of Forum Acusticum, 2011, Aalborg, Denmark, pp. 1935–1940.

[9] Bor’ba s shumom na proizvodstve. Spravochnik [Control of noise at work.Directory]. Ed. Iudin E. Ia.Moscow,Mashinostroenie publ., 1985. 399 p.

[10] Isachenko A.A., Otkidach L.G., Nikiforov N.I. Vliianie geometrii sopla na uroven’ shuma pri plazmennoi rezke [Effect of nozzle geometry on the noise level in plasma cutting]. Trudy VNIIavtogenmash [Proceedings VNIIavtogenmash]. Moscow, issue 25, 1980, pp. 52–59.

[11] Il’nitskaia A.V., Otkidach L.G. Akusticheskie kharakteristiki plazmenno-dugovoi rezki metallov i voprosy bor’by s shumom [Acoustic characteristics of plasma arc metal cutting issues and noi se cont rol]. Trudy VNIIavtogenmash [Proceedings VNIIavtogenmash]. Moscow, issue 25, 1980, pp. 60–68.

[12] Otkidach L.G. Shumopogloshchaiushchie ustroistva v prot ses sakh mekhanizi rovannoi plazmennoi rezki [Sound-absorbing devices in the process of mechanized plasma cutting]. Svarochnoe Proizvodstvo [Welding International]. 1993, no. 3, pp. 23–25.