| 摘要 |
<p>Thermal lance appts. for perforating sheet material utilises an energy beam source e.g. an electron beam to which the workpiece is exposed by free openings in an auxiliary appliance which cover an area that is extensive enough to enable several perforations to be made simultaneously in thematerial. Both the workpiece and the auxiliary appliance are moved relative to the place at which he beams take effect, and both are moved at a different speed to avoid overheating of the auxiliary appliance. Movement is effected at times corresponding to successive relative movements of the auxiliary device and the workpiece and the energy is beamed in pulses onto the surface of the auxiliary appliance.</p> |
