Page 138 - Mechatronics for Safety, Security and Dependability in a New Era

Ch25-I044963.fm Page 122 Tuesday, August 1, 2006 3:36 PM
Ch25-I044963.fm
122
122 Page 122 Tuesday, August 1, 2006 3:36 PM

Se = ^ x SV x (SPe + SDe) (6)
SI
Le LV(LP + LD) (7)
Se: EB of spindle lubricant oil [kg-GAS] Le: EB of slide way lubricant oil [kg- GAS]
SRT: Spindle runtime in an NC program [s] SV: Discharge rate of spindle lubricant oil [L]
57: Mean interval between discharges [s] SPe: EB of spindle lubricant oil production [kg-GAS/L]
SDe: EB of spindle lubricant oil disposal [kg-GAS/L]
LUT: Slide way runtime in an NC program [s] LI: Mean interval between supplies [s]
LV: Lubricant oil quantity supplied to slide way [L]
LPe: EB of slide way lubricant oil production [kg-GAS/L]
LDe: EB of slide way lubricant oil disposal [kg-GAS/L]

Cutting tool (Te)
Cutting tools are managed from the view point of tool life. So, the tool life is compared with the
machining time to calculate the environmental burden in one machining. Also, the cutting tools,
especially for solid end mill, are made a recovery by re-grinding, so these points are considered to
construct environmental burden equation.

Te = - ^ ?x((TPe + TDe)x.TIV + RCNxRCe) (8)
MT: Machining time [s] TL: Tool life [s]
TPe: EB of cutting tool production [kg- GAS /kg] TDe: EB of cutting tool disposal [kg- GAS /kg]
TW: Tool weight [kg] RN: Total number of recovery
RCe: EB of tool recovery [kg- GAS]

Metal chip {CHe)
Metal chips are recycled to material by an electric heating furnace. This materialization process has to
be considered. This kind of equation is supposed to consider material kind, but an electrical intensity
of this kind of electric heating furnace is represent by kWh/t, so the equation constructed in this
research is calculated from the total metal chip weight.

CHe = (WPV-PV)xMDx WDe (9)
WPV: Work piece volume [cm ] PV: Product volume [cm ]
3
MD: Material density of work piece [kg/cm ] WDe: EB of metal chip processing [kg-GAS/kg]

CASE STUDY
In order to show the feasibility of developed system, a case study is introduced. Then, the impact
category is set to global warming to calculate the environmental burden. In this research, CO 2, CH 4
and N2O are evaluated based on Japanese data, which are decided from environmental report, technical
report, home page and industrial table (Tokyo Waterworks, 2002, Tokyo Electric Power Company,
2002, Nansai, 2002, Mizukami, 2002). Here, CH 4 and N2O emission is converted to equivalent CO2
emission using the characterization factors and total CO 2 emission is evaluated. Here, the global
warming potential (GWP) of 100 years (IPCC, 1995) is used for the characterization factors. The other
emission matters related to global warming are ignored, because there are no emissions about the
machining operations. In this case study, machine tool is MB-46VA (OKUMA Corp.), cutting tool is
carbide square end mill with 2 flutes and 30 deg. helical angle and workpiece is medium carbon steel
(S50C). The simple product shown in Figure 2 is evaluated.