ガス切断に関する二,三の実験(第5報)

切断効率におよぼす予熱の影響

抄録

By using specially made tips with varying numbers and pitch of circle diameter (P.C.D.) of preheating orifices, a cutting test was performed. The results of the cutting was compared on the basis of the maximum cut thickness that has been introduced by the authors as a convenient criterion for determining cutting ability.
The cutting ability was found to increase with increasing numbers of preheating orifices surrounding the cutting orifice, if sufficient amount of acetylene gas is used, but the rate of increase in cutting ability decreases with increasing numbers of preheating orifices. The relation is expressed in the following formula :
mf=(1-ε^-n+1/1.8)⋅m₀
If insufficient acetylene gas is used, the cutting ability is below that given by the above formula, depending on the acetylene gas flow and P.C.D. of preheating orifices. The formula for this relation is expressed as follows :
m=(1-ε^-a/F)⋅m_f
where m, m_f=a degree of cutting ability proportional to the cutting efficiency
m₀=the maximum of the above, being peculiar to a size of tip
n=nos. of preheating orifices
α=acetylene gas flow per one preheating orifice
F=a constant depending on n, size of tip and P.C.D.
ε=the base of natural logarithm
From the results it was also found that many flames issuing from many preheating orifices are more efficient than a single flame of the same amount of acetylene gas.
In addition, the direction of a preheating orifice relative to the cutting orifice has no great significance so far as no loss of cut happens. The effectiveness of propane gas is by no means less than that of acetylene, if preheating variables are properly chosen.