Cutting Fluid Effects on Machine Shop Air Quality

Transcription

1 Cutting Fluid Effects on Machine Shop Air Quality For IAB000 Zhong Chen Advisor: Dr. Steven Y. Liang Oct. 18, 000

2 Problem Description Occupational Safety and Health Administration (OSHA) requirements 0.5 mg/m 3 Upper Respiratory [Lubricants in Operation, 1996] Skin Contact [Lubricants in Operation, 1996]

3 Problem Description (cont.) smoke particles permanently suspended aerosols temporarily suspended aerosols haze fog mist drizzle Atmospheric Particles rain Particle size (micron)

4 Problem Description (cont.) Turning process evaporation liquid jet Grinding process splash evaporation liquid jet air belt wheel guard tool workpiece splash spin-off workpiece spin-off wheel

5 Objectives Quantitative modeling of aerosol generation and dissipation in shop floor environment during turning and grinding processes Multivariate validation of methodology based on experiments.

6 Flow Diagram of Modeling Spin-off model Splash model Evaporation model Statistic distribution model Dissipation model Aerosol concentration

7 Spin-off Modeling Drop mode Ligament mode Photograph of spin-off Film mode

8 Spin-off Modeling (cont.) Rotating cylindrical peripheral disk atomization model fluid input part 4 coating liquid layer film formation mode part 1 part part 3 droplet formation mode ligament formation mode

9 Spin-off Modeling (cont.) ❾ drop mode 1/ σ D = 6 R d ρ V θ 1/ ❾ ligament formation mode ❾ film formation mode /7 1/7 1 ρq D = C'R We 3 N R σ /7 D f = 105Q 1.7ΩR 0.5 f 0.8 σ ρ

10 Splash Modeling Based on splatter model and atomization theory Nozzle Cutting fluid The mechanics of the splash atomization is similar to the mechanism of drop formation mode in spin-off process Workpiece

11 Splash Modeling (cont.) ❾ Splash parameter ω= We e d We ❾ Splash distribution parameter D m, SMD, Re etc. => δ ❾ Aerosol generation rate in splash process πd η N =βξρu Φ 4 splash f splash (D)/Vol

12 Evaporation modeling Hertz-Knudsen formula [Jones, Frank E,199] W = E (M / πr)(p tr / T tr P min / T v ) W evaporation rate E evaporation coefficient M molecular weight of the evaporating substance R universal gas constant P tr, Ttr vapor pressure and temperature at the interface P min, T v vapor pressure and temperature at vapor region

13 Evaporation modeling - Temp. distribution calculation -D FEM model to calculate temperature distribution Overhead jet cooling Chip Tool Secondary zone Area of primary zone Area 1 of primary zone Workpiece Area 3 of primary zone Flank jet cooling

14 Evaporation modeling - Temp. distribution calculation Overhead Jet Cooling Using Goldstein and Franchett model to calculate the local heat-transfer coefficients in heat transfer from a flat surface to an oblique impinging liquid jet. Nu = 1.1 A (Pr Flank Jet Cooling 1 / 3 Re 0.7 j Model of flow parallel to both surfaces ( B + C cos m / D ) [Rohsenow w. 1973] h x x 1 / 3 1 / Nu x = = 0.33 (Pr )(Re j ) Re x 5 10 K ) e Φ )( r 5

15 Statistic Distribution Modeling Rosin-Rammler Rammler particle size distribution function Φ(D) = 1 exp D D m δ Volume distribution D m Droplet size (µm) distribution

16 Dissipation Modeling z φ r q"=constant R o R x θ y o

17 Dissipation Modeling (cont.) Dissipation Equation: D AB r 1 r r η A r + D AB r 1 sin θ θ η sin θ θ A + D AB r 1 sin θ η φ A = η t A BC: D η s AB = s= R q" IC: η( s,0) = η o Chapman-Enskog Formula for Diffusivity: D AB = T 3 / (M A + M pσ B AB ) / M Ω D A M B

18 Experiments Aerosol concentration Experimental instrument & equipment Instrument Equipment Accessory Aerosol size distribution Temp. distribution Cutting force Machine Closed control vol. Computer etc. Spin-off Splash Evaporation Temp. distribution Cutting force Dissipation Experimental Implementation

19 DataRam Aerosol Monitor DataRAM HotMeter 10/.5 µm Selector Omni-directional Inlet

20 Particle Measuring System Volume distribution Droplet size (µm) distribution Theoretical result Experimental result

21 Experiments (cont.) Experimental setup Flow rate control Closed control volume Workpiece Computer Sensor Instrument

22 Spin-off Result rotational speed 145 (rpm) calculation measurement rotational speed 1040 (rpm) calculation measurement rotational speed 000 (rpm) calculation measurement Aerosol generation rate (µg/m 3 s) /18 1/94 1/64 1/46 1/3 0 1/18 1/94 1/64 1/46 1/3 0 1/18 1/94 1/64 1/46 1/3 Comparison between analytical result and experimental data under different flow rate and constant rotational speeds

23 Spin-off Result (cont.) flow rate 1/18 () calculation measurement flow rate 1/64 () calculation measurement flow rate 1/3 () calculation measurement Aerosol generation rate (µg/m 3 s) Speed 145 Speed 540 Speed 1040 Speed Speed 145 Speed 540 Speed 1040 Speed Speed 145 Speed 540 Speed 1040 Speed 000 Comparison between analytical result and experimental data under different rotational speeds and constant flow rate

24 Splash Result (cont.) Jet Distance (cm) Aerosol Generation Rate (10-9 Kg/m 3 s) Volumetric Flow Rate (ml/s)

25 Dissipation Result Analytical result and experimental data under speed=1040 rpm and flow rate=1/94

26 Dissipation Result (cont.) Analytical result and experimental data under speed=1040 rpm and flow rate=1/94

27 Conclusion The quantified models have been developed based on atomization theory and machining processes mechanics to predict aerosol generation. Spin-off process dominates aerosol generation under relatively higher rotational speed or flow rate during turning process. Dissipation model makes it possible to predict aerosol concentration as a function of location and time.