Abstract
In our yard the stack cutting has been widely used in hull construction, especially in cutting structural members of identical pattern in cargo-oil tank compartment ordinarily up to 1/2 in. in thickness. For the success of this process the elimination of gap between stacked plates is most essntial. The authors investigated the effects of the gap on the cutting action and smoothness of the cut surface. In addition, the effectiveness of acetylene and propane gases which are commonly used for preheating were compared. The results showed that a gap located near the top or the bottom of the stack is permissible for securing a good surface if it does not exceed 0.2mm or so in extent. However, a gap located near the middle is detrimental even if it amounts to 0.2mm or less. It was also found that the cutting action by using propane is generally less active than that using acetylene, but in some cases of stack cutting the former is equivalent to or even higher than the latter.
In actual practice C-clamps and hydraulic clamping devices are used for the elimination of gaps. Motor-driven rail gided straight-line cutting machines and shape-cutting machines equiped with magnetic tracer and steel template are fully employed for obtaining accurate and smooth contour of cuts.
The use of stack ctting is largely a matter of economics. As compared with the ordinary cutting, the expense for gas consumption is slightly higher, but labour hours in marking, material handling and cutting are considerably less, and consequently the total cost may be reduced to a great extent.
