Cette information existe seulement en anglais.
Pre-heating and cutting
→ reduction of the hardness at the flame cut edge (microstructure)
→ reduction of local stress due to balancing of the temperature gradient
- min.-preheating temperature shall be reached over the entire plate thickness
← heating from lower subsurface, control at upper subsurface
- min.-preheating temperature shall be maintained during the entire cutting process
- measuring of temperature can be done with:
- thermo couple
- thermo chalk
- pyrometer
- covering of the upper plate surface during pre-heating for isolation
Experiences concerning pre-heating and avoiding of crackoccurence
- slow flame cutting speed approves lower preheating temperature
- if so a loss in hardness will be induced
- if the cutting speed is too slow, deep cut drag lines will occur
Attention: preheating-temperature and time for heat-up will increase with increasing plate thickness.
Post-heating
- subsequent heating or/and holding at elevated temperature is usefull/recommended (<= 250 °C), especially for thicker plates (>75mm)
- e.g. holding at elevated temperature may be done through piling of the hot uniform flame cut pieces or by post-heating of the flame cut pieces
- e.g. when preheating temperature can not be maintained during the entire cutting process (e.g. for lager flame cut size)